Implications of altered drug disposition in the elderly: studies of benzodiazepines

HIV, aging, and adherence: an update and future directions

PURPOSE OF REVIEW

To highlight recent data on antiretroviral adherence in older people living with HIV (PLWH), describe the most relevant pharmacokinetic antiretroviral studies, and identify critical research gaps in this population.

RECENT FINDINGS

Overall, studies have found that older PLWH are more likely to be adherent to antiretroviral therapy (ART). Although multiple methods to measure adherence are available (self-report, pharmacy refills, electronic device monitors, drug concentrations), there is currently no 'gold standard' adherence measure or sufficient evidence to suggest a preferred method in older patients. Recently, studies evaluating antiretroviral concentrations in hair and dried blood spots in older patients identified no major differences when compared with younger individuals. Similarly, although pharmacokinetic studies in older PLWH are scarce, most data reveal no significant pharmacokinetic differences in the aging population. Furthermore, no specific guidelines or treatment recommendations regarding ART dose modification or long-term toxicity in aging PLWH are available, mostly because of the exclusion of this population in clinical trials.

SUMMARY

How aging influences adherence and pharmacokinetics remains poorly understood. As the population of older PLWH increases, research focusing on adherence, toxicity, drug--drug interactions, and the influence of comorbidities is needed.

Drug Safety of Benzodiazepines in Asian Patients With Chronic Obstructive Pulmonary Disease

Purpose: Many comorbidities, including depression, anxiety, and insomnia, occur in patients with chronic obstructive pulmonary disease (COPD). These patients may be prescribed benzodiazepines (BZDs). However, there are some concerns that benzodiazepines increase the risk of drug overdose, hypercapnic respiratory failure, acute exacerbation and increased mortality. The aim of our study was to evaluate the drug safety of BZDs in patients with COPD. Methods: We used the National Health Insurance Research database in Taiwan from 2002 to 2016 to perform a retrospective cohort study. We enrolled patients who were exposed to the first prescription of BZDs, non-BZDs or a combination (mix user) after COPD diagnosis. We performed 1:1:1 propensity score matching in three groups. The outcomes were COPD with acute exacerbation and all-cause mortality. Poisson regression analysis was performed to evaluate the incidence rate ratios for the outcomes in the groups. Results: After propensity score matching, there were 2,856 patients in each group. After adjusting for confounding factors, we found that compared to BZD users, non-BZD and mix users had nonsignificant differences in outpatient management of acute exacerbations, hospitalization management of acute exacerbations, emergency department management of acute exacerbations and all-cause mortality. BZD and mix groups showed significantly increased admission for acute exacerbation of COPD compared with that of the nonuser group, with IRRs of 2.52 (95% CI, 1.52-4.18; p = 0.0004) and 2.63 (95% CI, 1.57-4.40; p = 0.0002), respectively. Conclusion: BZD, non-BZD, and mix users showed increased COPD-related respiratory events compared to nonusers in Asian subjects.

Slow Accumulation and Elimination of Diazepam and Its Active Metabolite With Extended Treatment in the Elderly

Age-related changes in disposition of diazepam and its principal active metabolite, desmethyldiazepam (DMDZ), during and after extended dosage with diazepam were studied in healthy volunteers. Eight elderly subjects (ages 61-78 years) and 7 young subjects (21-33 years) received 2.5 mg of diazepam twice daily for 15 days. Predose (trough) concentrations of diazepam and DMDZ were measured during the 15 days of dosing, and in the postdosage washout period. Kinetic properties were determined by nonlinear regression using a sequential drug-to-metabolite pharmacokinetic model. Steady-state plasma concentrations of diazepam and DMDZ were 30% to 35% higher in elderly subjects compared to young volunteers, and steady-state clearances correspondingly lower, though differences did not reach significance. Large and significant differences were found between young and elderly groups in mean half-life of diazepam (31 vs 86 hours; P < .005) and DMDZ (40 vs 80 hours; P < .02). Half-life values from the multiple-dose study were closely correlated with values from previous single-dose studies of diazepam (R² = 0.85) and DMDZ (R² = 0.94) in the same subjects. With extended dosing of diazepam in the elderly, slow accumulation and delayed washout of diazepam and DMDZ is probable. After discontinuation, withdrawal or rebound effects are reduced in likelihood, but delayed recovery from sedative effects is possible due to slow elimination of active compounds. Safe treatment of elderly patients with diazepam is supported by understanding of age-related changes in pharmacologic and pharmacokinetic properties.

Effect of Environmental Exposure and Pharmacogenomics on Drug Metabolism

BACKGROUND

Pesticides are major xenobiotic compounds and environmental pollutants, which are able to alter drug-metabolizing enzyme as well as pharmacokinetics of drugs. Subsequent to the release of the human genome project, genetic variations (polymorphism) become an integral part of drug development due to their influence on disease susceptibility/ progression of the disease and their impact on drug absorption, distribution, metabolism of active metabolites and finally excretion of the drug. Genetic polymorphisms crucially regulate pharmacokinetics and pharmacodynamics of drugs under the influence of physiological condition, lifestyle, as well as pathological conditions collectively.

OBJECTIVE

To review all the evidence concerning the effect of environmental exposure on drug metabolism with reference to pharmacogenomics.

METHODS

Scientific data search and review of basic, epidemiological, pharmacogenomics and pharmacokinetics studies were undertaken to evaluate the influence of environmental contaminants on drug metabolism.

RESULTS

Various environmental contaminants like pesticides effectively alter drug metabolism at various levels under the influence of pharmacogenomics, which interferes with pharmacokinetics of drug metabolism. Genetic polymorphism of phase I and phase II xenobiotic-metabolizing enzymes remarkably alters disease susceptibility as well as the progression of disease under the influence of various environmental contaminants at various levels.

CONCLUSION

Individual specific drug response may be attributed to a large variety of factors alone or in combination ranging from genetic variations (SNP, insertion, deletion, duplication etc.) to physiological setting (gender, age, body size, and ethnicity), environmental or lifestyle factors (radiation exposure, smoking, alcohol, nutrition, exposure to toxins, etc.); and pathological conditions (obesity, diabetes, liver and renal function).

Diazepam as an oral hypnotic increases nocturnal blood pressure in the elderly

BACKGROUND

No study has evaluated the cardiovascular effects of diazepam in elderly subjects that assume diazepam to induce sleep.

PURPOSE

The present study was carried out in order to evaluate the effects of chronic administration of diazepam as hypnotic drug on blood pressure (BP) and heart rate (HR) in healthy elderly subjects.

PATIENTS AND METHODS

Healthy, elderly subjects, aged 65-74 years, were treated with diazepam 5 mg or placebo-both administered once a day in the evening-for 4 weeks in two cross-over periods, each separated by a 2-week placebo period, according to a randomized, double-blind, cross-over design. At the end of each study period, clinical as well as 24-h ambulatory BP and HR were evaluated.

RESULTS

A total of 25 subjects were included in the analysis. At the end of a 4-week diazepam treatment, clinical as well 24-h BP and HR mean values were not significantly affected. Analysis of sub-periods showed that during night-time, systolic BP (SBP) values under diazepam were 7.6% higher than under placebo, with a mean difference of 7.9 mmHg (p < 0.01), diastolic BP (DBP) values were 5.8% higher, with a mean difference of 3.7 mmHg (p < 0.05 vs placebo) and HR values were 6.6% higher with a mean difference of 4.2 b/min (p < 0.05). The HR increase observed with diazepam persisted during the morning hours, whereas during the afternoon and evening hours SBP, DBP and HR values were similar in the two treatment groups.

CONCLUSIONS

In elderly subjects chronic assumption of diazepam as hypnotic agent produced an increase in BP, in particular SBP, during night-time and of HR during night-time and morning hours. These effects, which probably depend on a diazepam-mediated increase in sympathetic drive and decrease in vagal tone, might be of clinical relevance due to the role of increased BP and HR as independent predictors of cardiovascular morbidity and mortality.

Deprescribing Benzodiazepines in Older Patients: Impact of Interventions Targeting Physicians, Pharmacists, and Patients

Benzodiazepines (BZDs; including the related Z-drugs) are frequently targets for deprescribing; long-term use in older people is harmful and often not beneficial. BZDs can result in significant harms, including falls, fractures, cognitive impairment, car crashes and a significant financial and legal burden to society. Deprescribing BZDs is problematic due to a complex interaction of drug, patient, physician and systematic barriers, including concern about a potentially distressing but rarely fatal withdrawal syndrome. Multiple studies have trialled interventions to deprescribe BZDs in older people and are discussed in this narrative review. Reported success rates of deprescribing BZD interventions range between 27 and 80%, and this variability can be attributed to heterogeneity of methodological approaches and limited generalisability to cognitively impaired patients. Interventions targeting the patient and/or carer include raising awareness (direct-to-consumer education, minimal interventions, and 'one-off' geriatrician counselling) and resourcing the patient (gradual dose reduction [GDR] with or without cognitive behavioural therapy, teaching relaxation techniques, and sleep hygiene). These are effective if the patient is motivated to cease and is not significantly cognitively impaired. Interventions targeted to physicians include prescribing interventions by audit, algorithm or medication review, and providing supervised GDR in combination with medication substitution. Pharmacists have less frequently been the targets for studies, but have key roles in several multifaceted interventions. Interventions are evaluated according to the Behaviour Change Wheel. Research supports trialling a stepwise approach in the cognitively intact older person, but having a low threshold to use less-consultative methods in patients with dementia. Several resources are available to support deprescribing of BZDs in clinical practice, including online protocols.

p16INK4a , a Senescence Marker, Influences Tenofovir/Emtricitabine Metabolite Disposition in HIV-Infected Subjects

The goal of this study was to explore the relationships between tenofovir (TFV) and emtricitabine (FTC) disposition and markers of biologic aging, such as the frailty phenotype and p16^INK4a gene expression. Chronologic age is often explored in population pharmacokinetic (PK) analyses, and can be uninformative in capturing the impact of aging on physiology, particularly in human immunodeficiency virus (HIV)‐infected patients. Ninety‐one HIV‐infected participants provided samples to quantify plasma concentrations of TFV/FTC, as well as peripheral blood mononuclear cell (PBMC) samples for intracellular metabolite concentrations; 12 participants provided 11 samples, and 79 participants provided 4 samples, over a dosing interval. Nonlinear mixed effects modeling of TFV/FTC and their metabolites suggests a relationship between TFV/FTC metabolite clearance (CL) from PBMCs and the expression of p16^INK4a, a marker of cellular senescence. This novel approach to quantifying the influence of aging on PKs provides rationale for further work investigating the relationships between senescence and nucleoside phosphorylation and transport.

Unique Aspects of the Elderly Surgical Population: An Anesthesiologist's Perspective

Increasing life expectancies paired with age-related comorbidities have resulted in the continued growth of the elderly surgical population. In this group, age-associated changes and decreased physiological reserve impede the body's ability to maintain homeostasis during times of physiological stress, with a subsequent decrease in physiological reserve. This can lead to age-related physiological and cognitive dysfunction resulting in perioperative complications. Changes in the cardiovascular, pulmonary, nervous, hepatorenal, endocrine, skin, and soft tissue systems are discussed as they are connected to the perioperative experience. Alterations affect both the pharmacodynamics and pharmacokinetics of administered drugs. Elderly patients with coexisting diseases are at a greater risk for polypharmacy that can further complicate anesthetic management. Consequently, the importance of conducting a focused preoperative evaluation and identifying potential risk factors is strongly emphasized. Efforts to maintain intraoperative normothermia have been shown to be of great importance. Procedures to maintain stable body temperature throughout the perioperative period are presented. The choice of anesthetic technique, in regard to a regional versus general anesthetic approach, is debated widely in the literature. The type of anesthesia to be administered should be assessed on a case-by-case basis, with special consideration given to the health status of the patient, the type of operation being conducted, and the expertise of the anesthesiologist. Specifically addressed in this article are age-related cognitive issues such as postoperative cognitive dysfunction and postoperative delirium. Strategies are suggested for avoiding these pitfalls.

Pharmacokinetics of two common antiretroviral regimens in older HIV-infected patients: a pilot study

OBJECTIVES

The pharmacokinetics (PK) of antiretrovirals (ARVs) in older HIV-infected patients are poorly described. Here, the steady-state PK of two common ARV regimens [tenofovir (TFV)/emtricitabine (FTC)/efavirenz (EFV) and TFV/FTC/atazanavir (ATV)/ritonavir (RTV)] in older nonfrail HIV-infected patients are presented.

METHODS

HIV-infected subjects ≥ 55 years old not demonstrating the frailty phenotype were enrolled in an unblinded, intensive-sampling PK study. Blood plasma (for TFV, FTC, EFV, ATV and RTV concentrations) and peripheral blood mononuclear cells [PBMCs; for tenofovir diphosphate (TFV-DP) and emtricitabine triphosphate (FTC-TP) concentrations] were collected at 11 time-points over a 24-hour dosing interval. Drug concentrations were analysed using validated liquid chromatography-ultraviolet detection (LC-UV) or liquid chromatography tandem mass spectrometry (LC-MS/MS) methods. Noncompartmental pharmacokinetic analysis was used to estimate PK parameters [area under the concentration-time curve over 24 h (AUC0-24h ) and maximal concentration (Cmax )]. These parameters were compared with historical values from the general HIV-infected population.

RESULTS

Six subjects on each regimen completed the study. Compared with the general population, these elderly subjects had 8-13% decreased TFV AUC0-24h and Cmax , and 19-78% increased FTC and RTV AUC0-24h and Cmax . Decreased ATV AUC0-24h (12%) and increased Cmax (9%) were noted, while EFV exposure was unchanged (5%) with a 16% decrease in Cmax . Intracellular nucleoside/tide metabolite concentrations and AUC are also reported for these subjects.

CONCLUSIONS

This study demonstrates that the PK of these ARVs are altered by 5-78% in an older HIV-infected population. Implications of PK differences for clinical outcomes, particularly with the active nucleoside metabolites, remain to be explored. This study forms the basis for further study of ARV PK, efficacy, and toxicity in older HIV-infected patients.

[Total intravenous anaesthesia in geriatrics: the example of propofol]

The aim of this review is to analyse the changes in the pharmacology of the elderly patient using, as examples, the existing pharmacokinetics and pharmacodynamics models of propofol and data provided in the literature.

Risk of dementia in patients with insomnia and long-term use of hypnotics: a population-based retrospective cohort study

BACKGROUND

Hypnotics have been reported to be associated with dementia. However, the relationship between insomnia, hypnotics and dementia is still controversial. We sought to examine the risk of dementia in patients with long-term insomnia and the contribution of hypnotics.

METHODS

Data was collected from Taiwan's Longitudinal Health Insurance Database. The study cohort comprised all patients aged 50 years or older with a first diagnosis of insomnia from 2002 to 2007. The comparison cohort consisted of randomly selected patients matched by age and gender. Each patient was individually tracked for 3 years from their insomnia index date to identify whether the patient had a first diagnosis of dementia. Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

We identified 5693 subjects with long-term insomnia and 28,465 individuals without. After adjusting for hypertension, diabetes mellitus, hyperlipidemia, and stroke, those with long-term insomnia had significantly higher risks of dementia (HR, 2.34; 95% CI, 1.92-2.85). Patients with long-term insomnia and aged 50 to 65 years had a higher increased risk of dementia (HR, 5.22; 95% CI, 2.62-10.41) than those older than 65 years (HR, 2.33; 95% CI, 1.90-2.88). The use of hypnotics with a longer half-life and at a higher prescribed dose predicted a greater increased risk of dementia.

CONCLUSIONS

Patients with long-term use of hypnotics have more than a 2-fold increased risk of dementia, especially those aged 50 to 65 years. In addition, the dosage and half-lives of the hypnotics used should be considered, because greater exposure to these medications leads to a higher risk of developing dementia.

The influence of old age and poloxamer-407 on the hepatic disposition of diazepam in the isolated perfused rat liver

BACKGROUND AND PURPOSE

The normal liver sinusoidal endothelium is thin and punctuated with fenestrations 50-200 nm in diameter that filter endobiotics and xenobiotics. Defenestration of the liver sinusoidal endothelium in old age and after pre-treatment with poloxamer-407 (P407) has been shown to prevent the transfer of small chylomicrons across the liver sinusoidal endothelium. The aim of this study was to investigate the impact of liver sinusoidal endothelium fenestrations on the hepatic uptake of the highly protein-bound drug diazepam. We hypothesized that defenestration will reduce the hepatic extraction of drugs which are highly bound to albumin.

METHODOLOGY

The isolated perfused rat liver (IPRL) model and multiple indicator dilution technique were used to investigate the effect of fenestrations in the liver sinusoidal endothelium on the hepatic disposition of diazepam in old and young rats, and in young rats treated with P407 or vehicle. A bolus dose of (14)C-diazpeam and non-extracted tracers ((3)H-sucrose and Evans blue) was injected into the portal vein. The single-pass recovery of diazepam and markers and the apparent volume of distribution were determined.

RESULTS

Scanning electron microscopy confirmed reduced porosity of the liver sinusoidal endothelial cells in P407-treated rats and old rats compared to young and control rats. The fractional recovery of diazepam was significantly increased in P407-treated rats compared to controls (0.20 ± 0.16, n = 12, P407; 0.08 ± 0.05, n = 8, controls; p = 0.0029), and in old rats compared to young rats (0.15 ± 0.03, n = 11, old; 0.10 ± 0.02, n = 11, young; p = 0.0004) following a single pass.

CONCLUSION

Defenestration due to age-related pseudocapillarization and treatment with P407 resulted in reduced hepatic extraction of diazepam after a single pass through the IPRL. These results highlight the importance of the liver sinusoidal endothelium in the ultrafiltration of highly protein-bound drugs, and may also provide an additional mechanism for reduced hepatic clearance of diazepam in conditions associated with defenestration.

Sex differences in the burying behavior test in middle-aged rats: effects of diazepam

The full behavioral profile displayed during the burying behavior test was studied in middle aged (11-14 months) males, females with irregular estrous cycles, and females in persistent diestrus, with and without diazepam (0.5-2.0mg/kg). Ambulation and motor coordination were also tested to discern behavioral changes from general motor alterations. Without diazepam treatment, middle-aged males showed longer burying behavior latencies, more prod explorations and less freezing than both groups of females. Untreated middle aged males also showed less cumulative burying and more immobility compared to females with irregular cycles. None of the parameters showed any difference between the female groups. Diazepam (0.5 and 1.0mg/kg) increased burying behavior latency in females, but had no effect on any parameter in middle aged males. However, a higher dose (2.0mg/kg) of diazepam increased immobility, freezing and the number of prod shocks and decreased prod explorations and groomings, but impaired motor coordination in males. In contrast with young males and females, diazepam at any dose reduced cumulative burying. Data are discussed on the bases of (1) sex and age differences in burying behavior and on (2) the anxiolytic-like action of diazepam and its side effects.

Differential effects of the dual orexin receptor antagonist almorexant and the GABA(A)-α1 receptor modulator zolpidem, alone or combined with ethanol, on motor performance in the rat

Current insomnia treatments such as γ-aminobutyric acid (GABA) receptor modulators are associated with sedative and muscle-relaxant effects, which increase when drug intake is combined with alcohol. This study compared the novel sleep-enabling compound almorexant (ACT-078573-hydrochloride), a dual orexin receptor antagonist, with the positive GABA(A)-α1 receptor modulator zolpidem. Both compounds were administered alone or in combination with ethanol, and their effects on forced motor performance were determined in Wistar rats upon waking after treatment. To detect substance-induced sedation and myorelaxation, time spent on an accelerating rotating rod (rotarod) and forepaw grip strength were measured. Zolpidem (10, 30, and 100 mg/kg, p.o.) and ethanol (0.32, 1, and 1.5 g/kg, i.p.) dose-dependently decreased rotarod performance and grip strength, whereas almorexant (30, 100, and 300 mg/kg, p.o.) did not. Doses of ethanol (0.32 and 1 g/kg), which were ineffective when administered alone, showed interactions with zolpidem (10 and 30 mg/kg) leading to reduced rotarod performance and grip strength; in contrast, combination of ethanol (0.32 and 1 g/kg) with almorexant (100 and 300 mg/kg) did not reduce performance or grip strength below ethanol alone. We conclude that unlike zolpidem, almorexant does not interfere with forced motor performance or grip strength in the rat, nor does it further increase the sedative effects of ethanol. Our results suggest that the effect of almorexant can be immediately reversed to full alertness like under physiological sleep, and that almorexant is less likely to show strong sedation, excessive myorelaxation, or interaction with alcohol than commonly prescribed hypnotics such as zolpidem.

The effect of sleep medications on cognitive recovery from traumatic brain injury

OBJECTIVE

To summarize the literature on the available pharmacotherapy for insomnia and the adverse cognitive effects of those options in persons with traumatic brain injury (TBI).

DESIGN

Ovid/MEDLINE databases were searched by using the following key words: "brain injury," "sleep initiation and maintenance disorders," "hypnotics and sedatives," "benzodiazepines," "trazodone," and "neuronal plasticity."

RESULTS

The reviewed literature consistently reported that benzodiazepines and atypical gamma-aminobutyric acid (GABA) agonists result in cognitive impairment when plasma levels are at their peak. Evidence of residual effects on cognition was reported for benzodiazepines but was seen less often in atypical GABA agonists. However, evidence has also been presented that GABA agonists have adverse effects on neuroplasticity, raising concerns about their use in patients recovering from TBI.

CONCLUSIONS

Use of benzodiazepines in TBI has been discouraged and some authors also advocate caution in prescribing atypical GABA agonists. Alternate treatments including trazodone and a newer class of agents, melatonin agonists, are highlighted, along with the limited data available addressing the use of these medications in TBI. Finally, suggestions are offered for further research, especially on topic related to neural plasticity and functional recovery.

Pharmacokinetics and drug metabolism in the elderly

Aging involves progressive impairments in the functional reserve of multiple organs, which might also affect drug metabolism and pharmacokinetics. In addition, the elderly population will develop multiple diseases and, consequently, often has to take several drugs. As the hepatic first-pass effect of highly cleared drugs could be reduced (due to decreases in liver mass and perfusion), the bioavailability of some drugs can be increased in the elderly. Significant changes in body composition occur with advancing age. Lipophilic drugs may have an increased volume of distribution (Vd) with a prolonged half-life, and water-soluble drugs tend to have a smaller Vd. In the elderly, hepatic drug clearance of some drugs can be reduced by up to 30% and CYP-mediated phase I reactions are more likely to be impaired than phase II metabolism, which is relatively preserved in the elderly. Concerning the most important CYP3A4 studies with human liver microsomes and clinical studies with the validated probe, midazolam, it is indicated that there are no significant differences in CYP3A4 activity between young and old populations. Finally, renal excretion is decreased (up to 50%) in about two thirds of elderly subjects, but confounding factors such as hypertension and coronary heart disease account also for a decline in kidney function. In conclusion, age-related physiological and pharmacokinetic changes as well as the presence of comorbidity and polypharmacy will complicate drug therapy in the elderly.

Population analyses of atorvastatin clearance in patients living in the community and in nursing homes

The effects of demographic and clinical covariates on the apparent clearance (CL/F) of orally administered atorvastatin, with chronic dosing in a patient population that included the elderly, were studied in 143 patients (atorvastatin: 34 +/- 26 mg/day, mean +/- SD; men (n = 64), age 64.6 +/- 12.1 years, and women (n = 79), age 69.3 +/- 13 years). The time of dose administration had a strong influence on Ka (faster with morning dosing); the factors found to slow CL/F were coadministration of CYP3A inhibitors and advancing age--the latter factor was relevant only in the men, not in the women.

The effect of chronic benzodiazepine use on cognitive functioning in older persons: good, bad or indifferent?

OBJECTIVE

This study investigates the effects of benzodiazepine (BZ) use on cognitive performance in elderly persons in a longitudinal design.

STUDY DESIGN AND SETTING

Data were obtained from the Longitudinal Aging Study Amsterdam (LASA), in the Netherlands. 2,105 respondents (>/=62 years of age) were included and had repeated measurements over a period of 9 years. For all BZs the type, dosage, frequency and duration of use was measured. The equivalent of a dose of diazepam was determined with regard to type and dosage and a cumulative dosage was calculated. General cognitive functioning was measured with the Mini-Mental State Examination, information processing speed was measured with the coding task, fluid intelligence with Raven's Coloured Progressive Matrices and episodic memory with the Auditory Verbal Learning Test. Multilevel analyses were used to investigate the relationship between BZ use and cognitive decline.

RESULTS

A negative effect of BZ use on cognitive performance was found. However, the effect sizes were very small.

CONCLUSION

This study suggests that both duration and cumulative exposure to BZ has a small negative effect on the long-term cognitive functioning of elderly people in the community.

The effect of chronic lorazepam administration in aging mice

To assess benzodiazepine tolerance in aged animals, lorazepam or vehicle was administered chronically to male Crl: CD-1(ICR)BR mice. Pharmacodynamic and neurochemical endpoints were examined on days 1 and 14 of drug administration. There was no age-related significant difference in plasma lorazepam levels. Young and middle-aged animals demonstrated behavioral tolerance to lorazepam, while the aged animals showed a similar trend which failed to reach significance. In addition, aged animals also showed a trend toward tolerance to the anticonvulsant effects of lorazepam. There were no changes in alpha1 mRNA levels in cortex or hippocampus following administration of lorazepam when compared to vehicle-treated animals in any age group. Aged animals, however, had an initial increase in alpha1 mRNA expression in cortex and hippocampus on day 1 of vehicle treatment followed by decreased expression on day 14. These age-related changes were abolished by lorazepam administration. In summary, age-related sensitivity to the effects of lorazepam was not demonstrated in the present study. However, comparison of these data to other studies indicates that the effect of chronic benzodiazepine treatment may be specific to the benzodiazepine administered, the technique used to quantify mRNA expression changes, the subunits of the GABA(A) receptor investigated and the brain region analyzed. The phenomenon of benzodiazepine sensitivity in the elderly is an area of research which remains controversial and may well be compound specific. Determining benzodiazepines that do not produce pharmacodynamic sensitivity, such as lorazepam, may allow more careful prescribing and dosing of these drugs, and perhaps even the development of specific agents which could avoid this sensitivity.

Role of valproate across the ages. Treatment of epilepsy in the elderly

In June 2005, a team of experts participated in a workshop with the objective of reaching agreement on several important aspects of valproate in the treatment of elderly patients with epilepsy. Epilepsy in the elderly is relatively common and its incidence increases for each decade after age 60. The aetiology and manifestations of epilepsies in the elderly are complex because of comorbidity and other underlying risk factors. A consensus was reached that elderly patients who present with a seizure disorder should be referred rapidly to a specialist and that diagnosis should be improved by using a multidisciplinary team of cardiologists, neurologists and epilepsy experts (syncope, falls and seizure specialists). This is especially important to avoid mistreatment with antiepileptic drugs (AEDs). There was consensus that the elderly are generally more susceptible to the adverse effects of AEDs than younger adults. For these reasons, in older persons AEDs should be started at low dosages, and titrated slowly according to clinical response. Some of the most troublesome side effects of AEDs in the elderly include sedation and cognitive side effects, as well as osteoporosis. Drug-drug interactions should be given special consideration. There was consensus that the pharmacokinetics of all AEDs are altered in the elderly, and that the most significant change common to all AEDs is a moderate reduction in renal and metabolic clearance. Predicting pharmacokinetic changes in the individual, however, can be very difficult because multiple factors contribute to a high inter-patient variability. There was agreement on the advantages and disadvantages of the use of valproate in the elderly, and consensus that valproate is a useful option in this population. There was no consensus, however, on whether valproate should be considered among the preferred first-line treatments in the elderly.

Sedative hypnotics in older people with insomnia: meta-analysis of risks and benefits

OBJECTIVES

To quantify and compare potential benefits (subjective reports of sleep variables) and risks (adverse events and morning-after psychomotor impairment) of short term treatment with sedative hypnotics in older people with insomnia.

DATA SOURCES

Medline, Embase, the Cochrane clinical trials database, PubMed, and PsychLit, 1966 to 2003; bibliographies of published reviews and meta-analyses; manufacturers of newer sedative hypnotics (zaleplon, zolpidem, zopiclone) regarding unpublished studies.

SELECTION CRITERIA

Randomised controlled trials of any pharmacological treatment for insomnia for at least five consecutive nights in people aged 60 or over with insomnia and otherwise free of psychiatric or psychological disorders.

RESULTS

24 studies (involving 2417 participants) with extractable data met inclusion and exclusion criteria. Sleep quality improved (effect size 0.14, P < 0.05), total sleep time increased (mean 25.2 minutes, P < 0.001), and the number of night time awakenings decreased (0.63, P < 0.001) with sedative use compared with placebo. Adverse events were more common with sedatives than with placebo: adverse cognitive events were 4.78 times more common (95% confidence interval 1.47 to 15.47, P < 0.01); adverse psychomotor events were 2.61 times more common (1.12 to 6.09, P > 0.05), and reports of daytime fatigue were 3.82 times more common (1.88 to 7.80, P < 0.001) in people using any sedative compared with placebo.

CONCLUSIONS

Improvements in sleep with sedative use are statistically significant, but the magnitude of effect is small. The increased risk of adverse events is statistically significant and potentially clinically relevant in older people at risk of falls and cognitive impairment. In people over 60, the benefits of these drugs may not justify the increased risk, particularly if the patient has additional risk factors for cognitive or psychomotor adverse events.

Optimizing antiepileptic drug therapy in the elderly

OBJECTIVE

To review and evaluate the medical literature concerning antiepileptic drug (AED) therapy in elderly patients.

DATA SOURCES

A MEDLINE search (1982-December 2004) was conducted. Bibliographies of the articles identified were also reviewed, and an Internet search engine was used to identify additional pertinent references.

STUDY SELECTION AND DATA EXTRACTION

Clinical studies and reviews were evaluated, and relevant information was included.

DATA SYNTHESIS

The elderly have the highest incidence of seizures among all age groups. Complex partial seizures are the most common, followed by primary generalized tonic-clonic seizures. An accurate diagnosis may prove difficult because of a low suspicion of epilepsy in the elderly and other diseases that may mimic seizures. Most AEDs are approved for treatment of elderly patients who have partial and tonic-clonic seizures. However, a number of age-related variables should be addressed when selecting an appropriate AED. Age-dependent differences in pharmacokinetics and pharmacodynamics of AEDs must be taken into account. Drug-drug interactions must be considered since elderly people often take multiple medications. The ultimate factor that often determines AED selection is tolerability.

CONCLUSIONS

Numerous factors must be considered in treating elderly patients for seizures, but maximizing the ability of patients to tolerate drug therapy is often the basis for AED selection. Special consideration should be made along several lines, including elderly patients' cognitive functioning and their tendency to respond to lower AED concentrations.

Effect of age on in vitro triazolam biotransformation in male human liver microsomes

We studied age-related changes in enzyme kinetic parameters in human liver microsomes (HLMs) in vitro, using triazolam (TRZ), an index of CYP3A activity. HLMs were prepared from male livers from four age groups, n = 5 per group: A (14-20 years), B (21-40 years), C (41-60 years), and D (61-72 years). Mean V(max) values in groups B and C for both 1-hydroxytriazolam (1-OH-TRZ) and 4-hydroxy-triazolam (4-OH-TRZ) formation were significantly greater as compared with groups A and D individually, as well as the net intrinsic clearance (sum of the two pathways). The mean net intrinsic clearance (Cl(int)) values were 25.2, 89.8, 78, and 20.6 nl/min/mg protein in A, B, C, and D, respectively. TRZ Cl(int) correlated well with total CYP3A content (r(s) = 0.84; P < 0.0001). Testosterone (TST) inhibited 1-OH-TRZ formation and activated 4-OH-TRZ formation in all age groups, with no significant differences among the groups; this suggests that the drug-drug interaction potential using TRZ and TST as index CYP3A substrates may not change with age. Reduced V(max) and Cl(int) for TRZ hydroxylation and CYP3A protein in livers from elderly men suggest reduced CYP3A gene expression in this group.

Benzodiazepine utilization patterns in Alzheimer's disease patients

BACKGROUND

Benzodiazepines (BZD) are commonly prescribed in the elderly. Persons with dementia may be at a greater risk of adverse reactions of BZD such as cognitive impairment.

OBJECTIVE

To assess the prevalence of BZD use in Alzheimer's disease patients and to examine patient and drug-characteristics associated with this use.

DESIGN

Cross-sectional study.

PARTICIPANTS

Five thousand community-dwelling and institutionalized patients initiating a treatment with tacrine for a mild to moderate Alzheimer's disease and included in the tacrine-study (Paco cohort).

MEASUREMENTS

Patient characteristics and BZD use recorded at the inclusion.

MAIN OUTCOME

Use of BZD during the 3 months prior to inclusion.

RESULTS

The 3-month prevalence of ever use of BZD was 20%. After controlling for age and gender, there was a non-significant inverse association between BZD use and a score of Mini-Mental Status Evaluation (MMSE) below 24 (OR: 0.88, 95% CI: 0.71-1.09), and significant inverse association with an increased number of chronic conditions (OR: 0.73, 95% CI: 0.58-0.91). Higher use of BZD was associated with higher level of overall drug consumption (OR: 2.3, 95% CI: 1.97-2.80).

CONCLUSION

Alzheimer's disease patients are frequently prescribed BZD. A low score of MMSE (< 24) is associated with a decreased use of BZD. These results suggest important differences in BZD use patterns among persons with Alzheimer's disease.

Strategies for optimizing antiepileptic drug therapy in elderly people

The elderly take more antiepileptic drugs (AEDs) than all other adults. This extensive use directly correlates with an increased prevalence of epilepsy in a growing population of older people, as well as other neuropsychiatric conditions such as neuropathic pain and behavioral disorders associated with dementia and for which AEDs are administered. The agents account for nearly 10% of all adverse drug reactions in the elderly and are the fourth leading cause of adverse drug reactions in nursing home residents. Numerous factors associated with advanced age contribute to the high frequency of untoward drug effects in this population; however, strategies are available to ensure optimal outcomes.

Plasticity of GABA(a) system during ageing: focus on vestibular compensation and possible pharmacological intervention

The lesion of the vestibular end organ evokes static and dynamic symptoms, which spontaneously regress during a complex process known as 'vestibular compensation'. Vestibular compensation is age-dependent and involves several transmitter-identified pathways in the central nervous system. In this paper we studied the time course of vestibular compensation in adult (3 months) and old (24 months) rats and correlated behavioral recovery with modifications of glutamic acid decarboxylase (GAD) mRNA expression and benzodiazepine receptor density in different brain areas. Compensation in adult rats was complete 28 days after hemilabyrinthectomy, whereas old rats still showed significant behavioral impairment. A higher GABAergic tone was found in old rats, as indicated by higher benzodiazepine receptor density in lateral vestibular nucleus and higher mRNA level for glutamic acid decarboxylase in cerebral cortex and medial vestibular nucleus. In adult, compensated rats, benzodiazepine receptor density in the vestibular nuclei was normal 28 days after lesion, whereas GAD mRNA level was higher in anterior cingulate cortex, only. On the contrary, these parameters were still altered in anterior cingulate and somatosensory cortex, basal ganglia, vestibular nuclei and cerebellum in old rats 28 days after vestibular lesion. We also evaluated the effect of the ergoline derivative nicergoline on behavioral and neurochemical correlates of vestibular compensation in old rats. Nicergoline treatment attenuated the severity of oculomotor and postural symptoms after vestibular lesion and reversed most of these age- and lesion-induced alterations in GAD mRNA expression. Thus, lesion-related alterations of the GABAergic transmission and behavioral profile after vestibular lesion are age-dependent.

Drug metabolism and drug interactions in the elderly

In the elderly concomitant use of several drugs (polypharmacy) is very common. Thus, the risk for drug interactions might be increased in this population. Since most drugs are hepatically eliminated by various metabolic pathways, liver function has to be considered as an additional factor modifying drug response. This chapter focuses on the hepatic mechanisms of interactions, especially on various inhibitors and inducers of the most important cytochrome P450 isoenzymes involved in drug metabolism. In addition, age-dependent changes in liver function are addressed. Based on pharmacokinetic results with different probe drugs, some inconsistencies in this area are discussed. The most important metabolic drug-drug interactions are independent of the age of the patients. However, since elderly patients consume a greater proportional share of drugs, they represent a population at risk for interactions. Awareness of this clinical problem may help to diminish those risks.

Pharmacologic management of epilepsy in the elderly

OBJECTIVE

To review the epidemiology and pharmacologic management of epilepsy in elderly patients.

DATA SOURCES

Controlled trials, case studies, and review articles identified via MEDLINE using the search terms epilepsy, seizures, elderly, phenobarbital, primidone, phenytoin, carbamazepine, valproic acid, felbamate, gabapentin, lamotrigine, topiramate, tiagabine, levetiracetam, oxcarbazepine, and zonisamide. Recently published standard textbooks on epilepsy were also consulted.

DATA SYNTHESIS

Epilepsy is a common neurologic disorder in the elderly. Cerebrovascular and neurodegenerative diseases are the most common causes of new-onset seizures in these patients. Alterations in protein binding, distribution, elimination, and increased sensitivity to the pharmacodynamic effects of antiepileptic drugs (AEDs) are relatively frequent, and these factors should be assessed at the initiation, and during adjustment, of treatment. Drug-drug interactions are also an important issue in elderly patients, because multiple drug use is common and AEDs are susceptible to many interactions. In addition to understanding age-related changes in the pharmacokinetics and pharmacodynamics of AEDs, clinicians should know the common seizure types in the elderly and the spectrum of AED activity for these seizure types. AEDs with activity against both partial-onset and generalized seizures include felbamate, lamotrigine, levetiracetam, topiramate, valproic acid, and zonisamide. Other AEDs discussed in this review (carbamazepine, gabapentin, phenobarbital, phenytoin, primidone, and tiagabine) are most useful for partial-onset seizures.

CONCLUSION

The provision of safe and effective drug therapy to elderly patients requires an understanding of the unique age-related changes' in the pharmacokinetics and pharmacodynamics of AEDs as well as an appreciation of common seizure types and the drugs that are effective for the specific types seen in the elderly.

Modification of ion channels and calcium homeostasis of basal forebrain neurons during aging

In this paper we review the last several years of work from our lab with attention to changes in the properties of basal forebrain neurons during aging. These neurons play a central role in behavioral functions, such as: attention, arousal, cognition and autonomic activity, and these functions can be adversely affected during aging. Therefore, it is fundamental to define the cellular mechanisms of aging in order to understand the basal forebrain and to correct deficits associated with aging. We have examined changes in the physiological properties of basal forebrain neurons during aging with whole-cell and single-channel patch-clamp, as well as, microfluorimetric measurements of intracellular calcium concentrations. These studies contribute to the understanding of integration within the basal forebrain and to the identification of age-related changes within central mammalian neurons. Although extensive functional/behavioral decline is often assumed to occur during aging, our data support an interpretation of compensatory increases in function for excitatory amino acid receptors, GABA(A) receptors, voltage-gated calcium currents and calcium homeostatic mechanisms. We believe that these changes occur to compensate for decrements accruing with age, such as decreased synaptic contacts, ion imbalances or neuronal loss. The basal forebrain must retain functionality into late aging if senescence is to be productive. Thus, it is critical to recognize the potential cellular and subcellular targets for therapeutic interventions intended to correct age-related behavioral deficits.

Benzodiazepine modulation of GABAergic responses is intact in the cerebellum of aged F344 rats

During the aging process there is a decline in the function of many central nervous system receptor systems. In this report we examine the ability of midazolam to potentiate gamma-aminobutyric acid (GABA) mediated inhibition recorded from cerebellar Purkinje neurons using extracellular recording methods. We report that when midazolam is applied concurrently with GABA from glass multibarrel electrodes that midazolam potentiates GABA mediated inhibition in 46% of Purkinje neurons in 3-month-old F344 rats, 63% of neurons in 18-month-old F344 rats and 54% of cells in 24-month-old F344 rats. Thus, there is no age related decline in function of this response. In fact, the response to midazolam is significantly increased in 18-month-old rats.

Lessons learned from the past: a guide for the future of clinical pharmacology in the 21st century

This article is a documentary of the history of the American College of Clinical Pharmacology (ACCP) and the Journal of Clinical Pharmacology. The history of the college and of the journal is presented as summarized by a few of the many leaders who played key roles in the growth of the profession of Clinical Pharmacology. Together, the college, the journal, and all clinical pharmacologists working in academia, industry, CROs, or government in many different subspecialty areas of the discipline contribute to the advancement of clinical pharmacology, the development of new drugs, and to an improved quality of life for mankind. Achieving leadership in health care in an era of change requires actions to be dynamic and flexible. Leaders must be capable of self-development and self-education. Leaders must examine challenges from top to bottom and build on the leadership foundations of vision, courage, and knowledge. Strong leaders are needed for the future of clinical pharmacology to address the rapidly changing environment for health care givers and the challenges faced by those working in drug development or training new leaders. One lesson from the past, from the professional life of Harry Gold, is that it is very important to convey the excitement of the field of clinical pharmacology and to pass on this excitement and knowledge base to those currently leading the educational process necessary to keep clinical pharmacologists in the forefront of the medical arena of today and tomorrow. The college became an instrument for change in the field of clinical pharmacology. Forward thinking efforts of the college did not allow stagnation. All founding leaders of the college were possessed of a dream of "what could be and what should be." Two points should be emphasized: the importance of teaching teachers how to teach and the importance of forming national networks, such as the college, to concentrate on the role of teaching students. Today's students are the leaders of tomorrow. The training of any given student in the field of clinical pharmacology continues over many years and requires the effort of many qualified mentors. The ACCP continues to prepare for the changing demands of a new millennium. The college responded to three challenges: (1) utilization of new technologies consistent with contemporary trends; (2) identification of new member services; and (3) dissemination of a position paper defining the philosophical foundations of the college. The basic tenant of the college remains the same today as it has been over the years: provide a multidisciplinary educational environment to have a broad appeal to the membership interested in clinical pharmacology.

GABAA and alpha-amino-3-hydroxy-5-methylsoxazole-4-propionate receptors are differentially affected by aging in the rat hippocampus

We have investigated the age-dependent modifications in the expression of eight different subunits of the gamma-aminobutyric acid, type A (GABA(A)) receptor (alpha1, alpha2, alpha3, alpha5, beta2, beta3, gamma2S, and gamma2L) and all four subunits of the alpha-amino-3-hydroxy-5-methylsoxazole-4-propionate (AMPA) receptor (GluR1-4) in the hippocampus of 24-month-old rats. All aged hippocampi displayed a remarkable increase (aged/adult ratio, 3.53 +/- 0.54) in the mRNA levels of the short version of the gamma2 subunit in parallel with a similar increase in the gamma2 subunit protein (aged/adult ratio, 2.90 +/- 0.62). However, this increase was not observed in the mature receptor. On the other hand, the expression of the different alpha subunit mRNAs increased moderately with aging, displaying a heterogeneous pattern. The most frequent modification consisted in an increase in the expression of the alpha1 subunit mRNA (aged/adult ratio, 1.26 +/- 0.18), in parallel with a similar increase on the alpha1 protein (aged/adult ratio, 1. 27 +/- 0.12) and in the alpha1 incorporated to the assembled GABA(A) receptor (tested by immunoprecipitation; aged/adult ratio, = 1.20 +/- 0.10). However, in the same hippocampal samples, no major modifications were observed on the expression of the AMPA receptor subunits. As a whole, these results indicated the existence of an increased expression of the GABA(A) receptor subunits and a preservation of the AMPA receptor at the hippocampal formation. These modifications could reflect the existence of specific deficiencies (neuronal loss and/or deafferentiation) on the GABAergic system in the aged rats.

Oxidative injury reproduces age-related impairment of oxygen-dependent drug metabolism

The Oxygen Diffusion Barrier Hypothesis states that aging in the liver is associated with restricted oxygen uptake that explains the age-related impairment of phase I drug clearance observed in vivo with preservation of in vitro phase I enzyme activity and in vivo phase II drug clearance. Aging in the liver may be secondary to oxidative stress. Therefore we examined the effects of oxidative injury on oxygen uptake, and phase I and phase II drug metabolism in the liver. Oxidative stress was induced in the perfused rat liver with hydrogen peroxide. The intrinsic clearances of propranolol and morphine were used as markers of phase I and phase II activity, respectively. Oxidative injury was associated with a 14+/-99% (P=0.03) reduction in oxygen uptake. The decrease in the intrinsic clearance of propranolol was greater than that of morphine (57+/-14% vs 34+/-7% P<0.005). This result supports the concept of a restriction of oxygen supply constraining hepatic drug metabolism following oxidative stress. This has implications for aging and hepatic drug metabolism.

Age-related alteration of carbamazepine-serum protein binding in man

To determine whether biological maturation influences the kinetics of carbamazepine-serum protein binding, the carbamazepine free fraction (%) was investigated in the serum of 66 patients, ranging from 4 to 83 years, with epilepsy or trigeminal neuralgia, treated with carbamazepine alone or carbamazepine in combination with phenytoin, phenobarbital, and/or valproic acid, over a relatively long period. Biochemical parameters such as levels of albumin and non-glycated albumin showed a significant relationship with carbamazepine free fraction (r = -0.521, P < 0.001 for albumin; r = -0.700, P < 0.001 for non-glycated albumin). Non-glycated albumin was more strongly correlated with carbamazepine free fraction. The biochemical parameters showed a significant relationship with age (r =-0.243, P < 0.1 for albumin; r =0.666, P < 0.001 for glycated albumin; r = -0.459, P < 0.001 for non-glycated albumin; r = 0.640, P < 0.001 for carbamazepine free fraction). Glycated albumin (%), non-glycated albumin and carbamazepine free fraction (%) were strongly correlated with age, whereas albumin showed only a weak correlation with age. To evaluate the effects of ageing on carbamazepine-serum protein binding, the patients were divided into three groups according to age: children, 4-15 years; adults, 16-64 years; elderly, 65-83 years. Albumin and non-glycated albumin were much lower, and glycated albumin (%) and carbamazepine free fraction (%) much higher in the elderly group than in the other two groups. The results of this study showed that the major ligand of carbamazepine in the serum was non-glycated albumin, which decreased with age. These observations suggested that in elderly patients, the elevation of free carbamazepine concentrations in the serum caused by reduced non-glycated albumin levels, induces increases in the sensitivity of the pharmacological effects of carbamazepine and the risk of drug interactions.

Antiepileptic drug therapy in the elderly

Populations are aging, and the incidence of epilepsy is increased in the elderly population. These demographic facts emphasize the importance of understanding the use of antiepileptic drugs in older patients. Healthy elderly have expected alterations in renal blood flow, hepatic volume and function, and alterations in fat-to-lean ratio of body composition. All of these changes make elderly patients vulnerable to dose-related adverse effects of the standard antiepileptic drugs. Newly developed compounds without enzyme induction effects and renal routes of excretion may be more favorable for use in elderly patients.

Single-dose pharmacokinetics and pharmacodynamics of alprazolam in elderly and young subjects

The pharmacokinetics and pharmacodynamics of the benzodiazepine anxiolytic alprazolam (1 mg orally) were compared between young and elderly healthy volunteers. Eight young subjects (mean age 29.8 years) and eight elderly volunteers (mean age 68.4 years) received oral placebo and alprazolam (1.0 mg) in a randomized, double-blind, single-dose crossover study. In the elderly subjects, plasma concentrations were higher, although not significantly so, than in young volunteers 0.25, 0.5, and 0.75 hours after dosage. Apparent elimination half-life, time of maximum concentration, maximum concentration, volume of distribution, and apparent clearance were similar for the two groups. In both groups, alprazolam treatment (versus placebo) produced significant changes in typical benzodiazepine agonist effects, such as increased sedation and fatigue, reduced excitement, increased feelings of spaciness, and perception of thinking slowed. For some measures, the alprazolam-placebo difference was greater in young than in elderly subjects. In both groups, alprazolam significantly impaired performance on the digit-symbol substitution test (DSST). EEG studies indicated significant increases in relative beta amplitude (13-30 Hz range) after alprazolam compared to placebo. Percent DSST decrement and percent EEG change were highly correlated with plasma alprazolam concentrations for both groups. There were modest increases in alprazolam plasma concentration in the elderly compared to the younger group shortly after drug administration, but there was no evidence of increased sensitivity to the pharmacodynamic effects of alprazolam in the elderly.

Anticonvulsant therapy in aged patients. Clinical pharmacokinetic considerations

Alterations in drug disposition that occur with aging are now becoming widely recognised, and there is an increasing number of drugs for which the approach to therapy in elderly patients can be based on pharmacokinetic data. Both healthy aging and comorbid disease can alter the responsiveness of the body to drugs and to their absorption, distribution and elimination. Altered absorption in the elderly has not been documented after oral ingestion of any anticonvulsant drug. Increased adipose tissue in the elderly may raise the apparent volume of distribution (Vd) of lipid-soluble drugs. An increased Vd in the elderly has been shown for diazepam and clobazam, but not midazolam. The data are inconclusive for phenytoin and valproic acid (sodium valproate). The decreased plasma protein binding that often occurs in the elderly has few clinical consequences. The reduced liver function that to occur with aging seems to affect the elimination of drugs that are mainly cleared by oxidative metabolism [e.g. carbamazepine, phenytoin and phenobarbital (phenobarbitone)]. Reduced clearances for methylphenobarbital (methylphenobarbitone), diazepam, midazolam and clobazam occur in elderly men, but not in women. The reduced renal function that is seen in old age affects the disposition of drugs that are eliminated mainly by direct renal excretion. Thus. the clearances of vigabatrin and gabapentin correlate with creatinine clearance. Such considerations may help guide anticonvulsant dosage in the elderly.

Toxicity of nonsteroidal anti-inflammatory drugs in the elderly: is advanced age a risk factor?

We reviewed the pharmacokinetic, physiologic and epidemiologic data concerning nonsteroidal anti-inflammatory drug (NSAID)-induced gastropathy and renal insufficiency in the elderly through a structured critical reading of the literature. References were collected through a search of MEDLINE and consultation with experts in the field. While there is an abundance of pharmacokinetic data comparing relevant parameters in young and old subjects, methods are not uniform and findings are inconsistent. Prostaglandin physiology appears to be altered in older versus younger subjects. Most surprisingly, there is a scarcity of epidemiologic data examining the contribution of age as a risk factor for NSAID-induced ulcers and/or renal insufficiency. The data that do exist do not clearly support age as an independent risk factor; and we believe that comorbidities, comedications and past history are more important predictors of NSAID-induced toxicity than age and more relevant in regard to therapeutic decision-making for this patient population.

Management of epilepsy in the elderly

Epilepsy in elderly patients is a growing worldwide challenge; as the population ages, the prevalence of epilepsy increases. Management of epilepsy in elderly patients requires an understanding of their unique medical and pharmacologic characteristics. Accurate assessment of seizures, thorough neurologic assessment to define etiology, and evaluation of concomitant illnesses and living situations are necessary for comprehensive treatment planning and informed management. Expect elderly patients to present challenges to treatment that include concomitant diseases, obligatory polypharmacy with accompanying drug interactions, and age-related changes in renal and hepatic physiology that alter drug metabolism and elimination. Elderly patients have declining intellectual function, motor impairment, or altered special sensory function that make them susceptible to dose-related CNS side effects of antiepileptic drugs (AEDs). When AEDs are added to the medical regimen of an elderly patient, the physician must review all prescribed drugs. Drugs prescribed for concomitant illnesses such as behavioral problems, cardiovascular disease, hypertension, and infection may alter the distribution and metabolism of AEDs, with an impact on efficacy and occurrence of adverse effects. AEDs tend to induce metabolism of other drugs, leading to a decline in target response. Optimal care of elderly patients with epilepsy includes use of free levels to monitor AED concentrations, careful dose selection, and physician sensitivity to patients' social problems.

Pharmacokinetic changes in the elderly. Do they contribute to drug abuse and dependence?

The elderly frequently use psychoactive drugs including alcohol (ethanol), benzodiazepines and opioid analgesics, which have a propensity to cause abuse and dependence. Theoretically, the changes in pharmacokinetics of these agents in the elderly may modify their abuse and dependence potential. In the elderly, blood alcohol concentrations following an oral dose are higher, alcohol withdrawal syndrome follows a more severe and protracted clinical course and requires treatment with higher doses of chlordiazepoxide than needed for younger adults. However, there is no direct evidence that supports an increased direct abuse and dependence potential of alcohol because of its altered kinetics in the elderly. In the case of oxidatively metabolised benzodiazepine, both age-related pharmacokinetics and pharmacodynamic changes may increase their clinical effects in the elderly. The hypothesis that benzodiazepines have an increased abuse and dependence potential in the elderly has not been tested. Many of the benzodiazepines (e.g. alprazolam, triazolam and midazolam) are metabolised by the cytochrome P450 (CYP)3A subfamily. The pharmacokinetics of these agents may be modified by inhibition of CYP3A due to concurrently administered medications such as selective serotonin reuptake inhibitors. Unfortunately, data on the direct measures of abuse and dependence potential of benzodiazepines are not available in the elderly. Thus, a conclusive statement on the contribution of age-related pharmacokinetic changes to benzodiazepine abuse and dependence cannot be made at the present time. The clinical effects of codeine do not appear to change with age. Codeine is O-demethylated to its active metabolite morphine by the genetically polymorphic CYP2D6 isozyme. The activity of this isozyme is unaltered by age, gender or smoking habits; however, it is subject to potent inhibition by some of the frequently used medications in the elderly, such as the antidepressants paroxetine and fluoxetine. This may result in an impairment in O-demethylation of codeine to morphine and may lead to a decrease in the abuse and dependence potential of codeine. Conversely, those with a very rapid CYP2D6 catalytic activity may have an increased potential for codeine abuse and dependence. The clinical significance of age-related pharmacokinetic changes should be evaluated within the context of clinical practice. Most physicians are inclined to prescribe lower doses to the elderly, which may offset the potential impact of altered pharmacokinetics on the abuse and dependence potential of psychoactive agents. In summary, the available data are not sufficient for a definitive conclusion on whether the pharmacokinetic changes in the elderly translate to an increase in the abuse and dependence potential of alcohol, benzodiazepines or opioids. In particular, the data on age-associated changes in direct measures of abuse potential of these agents are missing. Future comparative systemic pharmacokinetic-pharmacodynamic studies assessing pertinent outcome measures on abuse and dependence potential of commonly used psychoactive drugs are required to resolve the ongoing controversy on risk factors for drug abuse and dependence in the elderly.

Aging-related subunit expression changes of the GABAA receptor in the rat hippocampus

Aging-related changes in the subunit expression of some hippocampal GABAA receptors have been found. Quantitative in situ hybridization has revealed that alpha 1, subunit messenger RNA expression was significantly increased in the hippocampus (34%) of old rats. The largest increases were observed in the dentate gyrus (76%) and in the CA1 field (30%). Quantitative immunocytochemistry also showed increased protein expression of the alpha 1 subunit in the dentate gyrus (19%) and CA1 (14%) of old rats. The increased alpha 1 messenger RNA and protein expression led to increased proportions of assembled GABAA receptors that contained alpha 1 subunits, as revealed by quantitative immunoprecipitation of (3H)flunitrazepam and (3H)muscimol binding. In contrast, there were no significant changes in the expression of beta 2, beta 3 and total gamma 2 (gamma 2S + gamma 2L) subunits, although a slightly increased expression of gamma 2L peptide was detected in the hippocampus proper (7%), but not in the dentate gyrus. The results are consistent with the notion that in the rat hippocampus there is an aging-related change in the subunit composition of some GABAA receptors.

The gamma subunits of the native GABAA/benzodiazepine receptors

Subunit-specific antibodies to all the gamma subunit isoforms described in mammalian brain (gamma(1), gamma(2S), gamma(2L), and gamma(3) have been made. The proportion of GABA(A) receptors containing each gamma subunit isoform in various brain regions has been determined by quantitative immunoprecipitation. In all tested regions of the rat brain, the gamma(1) and gamma(3) subunits are present in considerable smaller proportion of GABA(A) receptor than the gamma(2) subunit. Immunocytochemistry shows that gamma(1) immunoreactivity concentrates in the stratum oriens and stratum radiatum of the CA1 region of the hippocampus. In the dentate gyrus, gamma(1) immunoreactivity concentrates on the outer 2/3 of the molecular layer coinciding with the localization of the axospinous synapses of the perforant pathway. In contrast, gamma(3) immunoreactivity concentrates on the basket cells and other GABAergic local circuit neurons of the hilus. These cells are also rich in gamma(2S). In the cerebellum, gamma(1)++ immunolabeling was localized on the Bergmann glia. The gamma(2S) and gamma(2L) subunits are differentially expressed in various brain regions. Thus the gamma(2S) is highly expressed in the olfactory bulb and hippocampus whereas the gamma(2L) is very abundant in inferior colliculus and cerebellum, particularly in Purkinje cells, as immunocytochemistry, in situ hybridization and immunoprecipitation techniques have revealed. The gamma(2S) and gamma(2L) coexist in some brain areas and cell types. Moreover, the gamma(2S) and gamma(2L) subunits can coexist in the same GABA(A) receptor pentamer. We have shown that this is the case in some GABA(A) receptors expressed in cerebellar granule cells. These GABA(A) receptors also have alpha and beta subunits forming the pentamer. Immunoblots have shown that the rat gamma(1), gamma(2S), gamma(2L) and gamma(3) subunits are peptides of 47, 45, 47 and 44 kDa respectively. Results also indicate that there are aging-related changes in the expression of the gamma(2S) and gamma(2L) subunits in various brain regions which suggest the existence of aging-related changes in the subunit composition of the GABA(A) receptors which in turn might lead to changes in receptor pharmacology. The results obtained with the various gamma subunit isoforms are discussed in terms of the high molecular and binding heterogeneity of the native GABA(A) receptors in brain.

Altered expression of gamma 2L and gamma 2S GABAA receptor subunits in the aging rat brain

Aging-related alterations in both protein and mRNA expression of gamma 2S and gamma 2L subunits of the GABAA receptors have been observed in several brain areas of Sprague-Dawley and Fischer 344 rats. Subunit-specific antibodies to gamma 2S and gamma 2L as well as a riboprobe to the large intracellular loop of gamma 2, which recognizes both gamma 2S and gamma 2L mRNAs, in conjunction with computerized image analysis were used for quantitative immunocytochemistry and in situ hybridization. In addition, specific oligonucleotide probes to gamma 2S or gamma 2L mRNA were used for quantitative dot blot hybridization. A large increase in the number of heavily immunostained neurons with the anti-gamma 2L antibody was detected in the cerebral cortex (115%) of old rats. However, only a small (but significant) aging-related increase in the density of gamma 2L immunostaining (7%) was observed throughout the cerebral cortex whereas no significant aging-related change in gamma 2L mRNA was detected in this brain region. Contrary to gamma 2L, the gamma 2S immunostaining did not show aging-related increased number of heavily immunostained neurons in cerebral cortex. Moreover, the density of gamma 2S immunostaining and the expression of gamma 2S mRNA were significantly decreased in the cerebral cortex (9-24%). Important aging-related changes were also found in the cerebellum of old rats where the expression of both gamma 2S and gamma 2L peptides was significantly decreased (24% and 23% respectively). This decrease in gamma 2 protein expression was accompanied by decreased expression of gamma 2S (16-38%) and gamma 2L (24%) mRNAs. Nevertheless, the most important decrease of gamma 2S (48%) and gamma 2L protein (20%) was revealed in the molecular layer of the cerebellum. In addition, the expression of gamma 2S protein was increased (14%) whereas the expression of gamma 2L was decreased (13%) in the granule cell layer. Therefore, the relative expression of gamma 2S protein in both layers was reversed in old animals. The observed aging-related changes in the expression of GABAA receptor subunits might lead to altered GABAA receptor/benzodiazepine receptor subunit composition.

Epidemiology of adverse drug events in the nursing home setting

There is widespread concern about the level of use, particularly the inappropriate use, of drugs among elderly residents of nursing homes. Medication consumption by these individuals is among the highest of any patient population; residents of nursing homes are prescribed an average of 5 to 8 regularly scheduled medications in addition to those drugs prescribed on an as needed ('prn') basis. Ideally, drug therapy should result in beneficial effects and improved quality of life for patients. However, the development of adverse drug events (ADEs) can compromise the expected benefits of pharmacotherapy for the individual nursing-home resident and may represent a public health problem of considerable magnitude.

The effect of age on pharmacokinetics of antiepileptic drugs

Management of epilepsy in the elderly requires understanding of the unique biochemical and pharmacologic characteristics of this patient population. Accurate assessment of seizures and identification of epilepsy syndromes, thorough neurologic assessment to define etiology, and comprehensive evaluation of the patient's health and living situation are necessary for informed management decisions. Challenges to treatment include concomitant diseases, polypharmacy with accompanying drug interactions, and changes in physiology, such as changes in renal clearance and hepatic function than alter drug absorption, protein binding, metabolism, and elimination. Elderly patients with declining intellectual function, motor impairment, or altered sensory function may be especially susceptible to dose-related CNS side effects of antiepileptic drugs (AEDs). Drugs prescribed for concomitant illnesses such as hypertension, cardiovascular disease, infections, behavioral problems, and gastrointestinal disturbances may alter absorption, distribution, and metabolism of AEDs, with an adverse impact on efficacy and increased occurrence of adverse effects. The AEDs may induce metabolism of other drugs, resulting in decline in target response. Addition of an AED to an elderly patient's medical regimen requires careful review of all prescribed drugs. Optimal care of elderly patients with epilepsy includes use of free drug levels to monitor AED concentrations, careful dose selection, and sensitivity to the social problems that may occur in this population.