Clinical pharmacokinetics of anxiolytics and hypnotics in the elderly. Therapeutic considerations (Part II)

The association of change in peak oxygen uptake with use of psychotropics in community-dwelling older adults - The Generation 100 study

BACKGROUND

The use of psychotropics is high among the older population and may have detrimental effects on their physical and mental health. Cardiorespiratory fitness (CRF) is a strong and modifiable measure of health and declines with age. We aimed to study the association of change in CRF with use of psychotropics in community-dwelling older adults.

METHODS

We analyzed longitudinal data from 1531 older adults from the Generation 100 study, aged 70-77 years at inclusion, and with a permanent address in Trondheim, Norway. Data on objectively measured peak oxygen uptake (VO_2peak) were linked with register data from the Norwegian Prescription Database on prescribed psychotropics. The included psychotropics were antidepressants (N06A), antipsychotics (N05A), anxiolytics (N05B), hypnotics and sedatives (N05C), and N03AE (benzodiazepine derivatives). Analyses were done on any psychotropics as one group, and on the following separate groups: antidepressants (N06A), benzodiazepines (N05BA, N05CD, and N03AE), and z-hypnotics (N05CF). Peak oxygen uptake was measured four times over a five-year period and corresponding medication use was measured as defined daily doses (DDD). A random effects estimator was applied to investigate the association of change in VO_2peak with the use of psychotropics.

RESULTS

We found a statistically significant curvilinear association of change in VO_2peak with use of any psychotropics and antidepressants. For VO_2peak up to ~ 40 ml/kg/min, each 1 ml/kg/min increase was associated by a 3.3 DDD and 2.5 DDD decrease in use of any psychotropics and antidepressants, respectively. A bottoming-out effect was found and increases in VO_2peak above ~ 40 ml/kg/min showed increased use of any psychotropics and antidepressants. However, the association of change in VO_2peak with use was stronger for changes in the lower continuum of VO_2peak levels and decreased with increasing VO_2peak. No statistically significant association of change in VO_2peak with use of benzodiazepines and z-hypnotics were found. However, because of a non-randomized design, we cannot rule out the possibility of confounding by indication.

CONCLUSIONS

The results of this study show a curvilinear association of change in VO_2peak with use of any psychotropics and antidepressants in older adults. This relationship adds a new viewpoint on the adverse effects of psychotropic use and should be considered in interventions and policies aimed at reducing psychotropic medication use among the older population.

Delirium and its Pharmacological Causes in Older People, Part Two

Delirium is a syndrome that can arise from many causes or underlying conditions, and though it has been reported in younger patients, it is more prevalent in older people, though it can occur in other age groups as well. Identifying delirium is challenging in older people because of the coexistence of underlying dementia or depression, which may further complicate the presentation. Drug-induced delirium is one of the major causes of delirium, and evaluation of this potential cause or contribution is an important component of the evaluation process, since it can lead to poor patient outcomes. Part one of this three part series reviewed the epidemiology, pathophysiology, evaluation, diagnostic process, and causes of delirium in older people, with a focus on the pharmacological causes. Part two of this series continues to review drugs and drug classes that can cause or contribute to delirium in older people.

Incidence of and Characteristics Associated With Long-term Benzodiazepine Use in Finland

IMPORTANCE

The proportion of patients who develop long-term benzodiazepine use remains controversial, as do the length of time before long-term use develops and the factors associated with long-term use.

OBJECTIVE

To investigate the incidence of long-term benzodiazepine and related drug (BZDR) use and factors associated with the development of long-term use implementing a follow-up design with new BZDR users.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study used a nationwide cohort of 129 732 new BZDR users in Finland. New users of BZDRs aged 18 years or older were identified from the prescription register maintained by the Social Insurance Institution of Finland as individuals who initiated BZDR use during 2006 and had not used BZDRs from 2004 to 2005. The follow-up continued until death, long-term hospitalization, a gap of 2 years in BZDR use, or December 31, 2015. The population was analyzed according to age at treatment initiation, categorized into younger (<65 years) and older (≥65 years) subcohorts. Analyses were conducted from May 2019 to February 2020.

EXPOSURES

Use of BZDRs, modeled from register-based data using the PRE2DUP (from prescriptions to drug use periods) method.

MAIN OUTCOMES AND MEASURES

Long-term BZDR use, defined as continuous use of 180 days or longer, and factors associated with long-term vs short-term use, compared using Cox proportional hazards models.

RESULTS

Among the 129 732 incident BZDR users, the mean (SD) age was 52.6 (17.7) years, and 78 017 (60.1%) individuals were women. During the follow-up period, 51 099 BZDR users (39.4%) became long-term users. Long-term treatment was more common in the older subcohort (19 103 individuals [54.5%]) than the younger subcohort (31 996 individuals [33.8%]). At 6 months, 28 586 individuals (22.0%) had become long-term users: 11 805 (33.7%) in the older subcohort and 16 781 (17.7%) in the younger subcohort. The largest proportions of initiators who became long-term users were those persons who initiated treatment with nitrazepam (76.4%; 95% CI, 73.6%-79.1%), temazepam (63.9%; 95% CI, 62.9%-65.0%), lorazepam (62.4%; 95% CI, 59.7%-65.1%), or clonazepam (57.5%; 95% CI, 55.9%-59.2%). Factors associated with the development of long-term use included male sex, older age, receipt of social benefits, psychiatric comorbidities, and substance abuse.

CONCLUSIONS AND RELEVANCE

The findings of this population-based cohort study conducted in Finland suggest that the incidence of subsequent long-term BZDR use in individuals who initiate use of BZDRs is high, especially among older persons, and that the specific BZDR used initially is associated with the development of long-term BZDR use and should be carefully considered when prescribing BZDRs. The observed factors that appear to be associated with development of long-term BZDR use also should be considered in clinical decision-making when starting and monitoring BZDR treatment.

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.

Psychological predictors of benzodiazepine discontinuation among older adults: Results from the PASSE 60

BACKGROUND

Long-term benzodiazepine (BZD) use among seniors is mostly inappropriate and associated with adverse health outcomes. To prevent these consequences, withdrawal is crucial, yet knowledge is limited about what predicts BZD discontinuation. Until now, most studies have focused on sociodemographic and BZD intake factors as predictors while neglecting psychological factors. This research addresses this issue by studying how the intensity of depressive symptoms, social support satisfaction, self-perceived competence in the ability to withdraw, and overall quality of sleep predict discontinuation in long-term older consumers.

METHOD

Seventy-three participants aged 60 years and older were enrolled in this study. There were four time measures: before discontinuation (T1), after (T2), 3 months after (T3), and 12 months after (T4). Data were collected in the "Programme d'Aide du Succès au SEvrage" (PASSE-60+) study.

RESULTS

Social support satisfaction predicted discontinuation at T2 and T4. Self-perceived competence in the ability to withdraw and depressive symptoms predicted discontinuation at T4. This later prediction was counterintuitive; higher depressive symptoms at T1 were linked with higher discontinuation success. BZD intake factors (length of use and dose) were good predictors for short term discontinuation. Psychological factors were moderate predictors for short term and good predictors for long term discontinuation.

CONCLUSION

Psychological factors are good predictors of discontinuation and are better predictors than BZD intake factors of long-term discontinuation. Discontinuation programs should focus on social support and self-perceived competence to improve their efficacy. Further studies are needed to acquire a more complete picture of the psychological predictors of discontinuation success. ClinicalTrials.gov Identifier: NCT02281175.

Benzodiazepine Consumption Is Associated With Lower Blood Pressure in Ambulatory Blood Pressure Monitoring (ABPM): Retrospective Analysis of 4938 ABPMs

BACKGROUND

The effect of chronic benzodiazepine use on blood pressure has not been documented. We aimed to evaluate whether regular benzodiazepine use can be associated to the results of ambulatory blood pressure monitoring (ABPM).

METHODS

A retrospective analysis of the ABPM database between 2009 and 2015 was performed. The study groups were divided according to benzodiazepine treatment at least 3 months before ABPM. Generalized estimating equation (GEE) model analysis was conducted to estimate the association between benzodiazepine treatment and ABPM test measurements. Multivariable COX regression survival analysis model for mortality and cardiovascular (CV) events was performed.

RESULTS

A total of 4,938 ABPM studies were included in final analysis, 670 ABPMs of benzodiazepine-treated patients, and 4,268 of untreated patients. The benzodiazepine-treated group was significantly older, with a predominance of female patients, comprised more diabetic patients and consumed more antihypertensive medications. Adjustment for age, gender, diabetes mellitus, and number of antihypertensive medications, showed an association between benzodiazepine treatment and significantly lower ABPM measurements. When the analysis was split into those ≥60 years old and the other <60 years old, regular benzodiazepine consumption was associated with lower ABPM measurements only among ≥60 years old. Multivariable Cox regression survival analysis showed that regular benzodiazepine consumption was not associated with increased mortality or CV events (mean follow-up period of 42.4 ± 19.8 and 42.1 ± 20.0 months, respectively).

CONCLUSIONS

Long-term use of benzodiazepines by ≥60 years old was independently associated with lower diastolic and systolic blood pressure in all parameters of ABPM, but not among younger patients.

Population Pharmacokinetics of Fentanyl in the Critically Ill

OBJECTIVE

To characterize fentanyl population pharmacokinetics in patients with critical illness and identify patient characteristics associated with altered fentanyl concentrations.

DESIGN

Prospective cohort study.

SETTING

Medical and surgical ICUs in a large tertiary care hospital in the United States.

PATIENTS

Patients with acute respiratory failure and/or shock who received fentanyl during the first 5 days of their ICU stay.

MEASUREMENTS AND MAIN RESULTS

We collected clinical and hourly drug administration data and measured fentanyl concentrations in plasma collected once daily for up to 5 days after enrollment. Among 337 patients, the mean duration of infusion was 58 hours at a median rate of 100 μg/hr. Using a nonlinear mixed-effects model implemented by NONMEM, we found that fentanyl pharmacokinetics were best described by a two-compartment model in which weight, severe liver disease, and congestive heart failure most affected fentanyl concentrations. For a patient population with a mean weight of 92 kg and no history of severe liver disease or congestive heart failure, the final model, which performed well in repeated 10-fold cross-validation, estimated total clearance, intercompartmental clearance (Q), and volumes of distribution for the central (V1) and peripheral compartments (V2) to be 35 L/hr (95% CI, 32-39 L/hr), 55 L/hr (95% CI, 42-68 L/hr), 203 L (95% CI, 140-266 L), and 523 L (95% CI, 428-618 L), respectively. Severity of illness was marginally associated with fentanyl pharmacokinetics but did not improve the model fit after liver and heart diseases were included.

CONCLUSIONS

In this study, fentanyl pharmacokinetics during critical illness were strongly influenced by severe liver disease, congestive heart failure, and weight, factors that should be considered when dosing fentanyl in the ICU. Future studies are needed to determine if data-driven fentanyl dosing algorithms can improve outcomes for ICU patients.

Individualization of drug therapy in older people

Older people are high consumers of prescription drugs and are at increasing risk of polypharmacy and adverse reactions. Pharmacokinetic and pharmacodynamic modifications due to age and co-morbidities are an important consideration, but pharmacological background evidence to guide safe and effective therapeutic approaches are often inadequate since the older population is under-represented in clinical trials. We review the pharmacokinetic and pharmacodynamic changes that are characteristic in old age and consider evidence regarding potentially safer prescription and monitoring of drugs commonly used in older patients. We also introduce the possible role of pharmacogenomics and therapeutic drug monitoring as tools to guide the individualization of drug therapy.

Psychotropic drug use among older people in general practice: discrepancies between opinion and practice

BACKGROUND

The use of psychotropic drugs has increased over recent years in France. GPs are the first prescribers, especially for older patients.

AIM

To analyse discrepancies between GPs' opinions and practice when prescribing psychotropic drugs to older patients.

SETTING

Postal surveys sent to GPs all over mainland France.

DESIGN OF STUDY

Cross-sectional postal study.

METHOD

A questionnaire collected data on characteristics of GPs' practices, their opinions about psychotropic drug consumption in older people, and a full description of their last older patient receiving a psychotropic drug and seen last by the GP on that particular day.

RESULTS

A total of 350 participating GPs saw 2498 patients aged > or =65 years. Among these patients, the prevalence of psychotropic use was 32.1% (803/2498) for anxiolytics/hypnotics, and 17.5% for antidepressants (438/2498). A total of 91% of GPs agreed that it was possible to reduce or stop psychotropic drugs for these patients. Characteristics of 339 patients taking psychotropic drug were reported: 85.8% (291/339) received at least one anxiolytic/hypnotic and 56.9% (193/339) received at least one antidepressant; there were prescribed for more than 1 year in 68.4% (199/291) and 43.5% (84/193) of the cases respectively. GPs stated that it was possible to reduce or stop anxiolytic/hypnotic drugs for only 27% (79/291) of these patients. Barriers to doing this were patients' refusal (79%), and the absence of any local offer of psychotherapy (73%) or alternative therapy (70%).

CONCLUSION

A mismatch exists between GPs' intent (91%) and practice (27%) regarding reduction of psychotropic prescription in individuals aged > or =65 years. The barriers encountered should be examined further to help physicians improve management of psychotropic prescription.

Effect of aging on glucuronidation of valproic acid in human liver microsomes and the role of UDP-glucuronosyltransferase UGT1A4, UGT1A8, and UGT1A10

Valproic acid (VPA) is a widely used anticonvulsant that is also approved for mood disorders, bipolar depression, and migraine. In vivo, valproate is metabolized oxidatively by cytochromes P450 and beta-oxidation, as well as conjugatively via glucuronidation. The acyl glucuronide conjugate (valproate-glucuronide or VPAG) is the major urinary metabolite (30-50% of the dose). It has been hypothesized that glucuronidation of antiepileptic drugs is spared over age, despite a known decrease in liver mass. The formation rates of VPAG in a bank of elderly (65 years onward) human liver microsomes (HLMs) were measured by liquid chromatography/tandem mass spectrometry and compared with those in a younger (2-56 years) HLM bank. In vitro kinetic studies with recombinant UDP-glucuronosyltransferases (UGTs) were completed. A 5- to 8-fold variation for the formation of VPAG was observed within the microsomal bank obtained from elderly and younger donors. VPAG formation ranged from 6.0 to 53.4 nmol/min/mg protein at 1 mM substrate concentration (n=36). The average velocities at 0.25, 0.5, and 1 mM VPA were 7.0, 13.4, and 25.4 nmol/min/mg protein, respectively, in the elderly HLM bank. Rates of VPAG formation were not significantly different in the HLM bank obtained from younger subjects. Intrinsic clearances (V(max)/K(m)) for several cloned, expressed UGTs were determined. UGT1A4, UGT1A8, and UGT1A10 also were found to catalyze the formation of VPAG in vitro. This is the first reported activity of these UGTs toward VPA glucuronidation. UGT2B7 had the highest intrinsic clearance, whereas UGT1A1 demonstrated no activity. In conclusion, our investigation revealed no differences in VPAG formation in younger versus elderly HMLs and revealed three other UGTs that form VPAG in vitro.

Pathophysiology of delirium in the intensive care unit

Delirium, or acute brain dysfunction, is a life-threatening global disturbance in cognitive functioning that frequently manifests in critically ill patients. This review examines the current status of knowledge regarding the pathophysiology of delirium in the ICU, in particular, evaluating the role of iatrogenic factors such as sedatives and analgesic administration in brain dysfunction. This hypothesis is considered along with several other plausible mechanisms of ICU delirium, including sepsis, postoperative cognitive dysfunction, and changes in biomarkers and neurotransmitters. The review concludes by highlighting potential future directions in molecular genetics for the elucidation of delirium and its long-term consequences.

Indiplon in the treatment of sleep disorders

Indiplon is a novel sedative-hypnotic recently approved for the treatment of insomnia. Like other non-benzodiazepine hypnotics, its mechanism of action is to modulate subunits, especially the alpha-1 subunit, of the GABA receptor complex in order to induce sedation. Indiplon was developed in two different formulations to address two different types of insomnia complaint: indiplon-IR (immediate release) was designed for sleep onset difficulties, while indiplon-MR (modified release) was developed for sleep maintenance insomnia. While there are currently few peer reviewed articles about indiplon clinical trial results, the early information that is available seems to indicate that both formulations have been well tolerated and have proven effective at improving both patient reported and objectively measured sleep parameters in both adult and elderly insomnia patients. In May 2006, the FDA indicated that indiplon-IR was approvable and plans are to resubmit the application in 2007. Indiplon-MR was unapprovable and may require further evaluation.

Dissociation between objective psychomotor impairment and subjective sleepiness after diazepam administration in the aged people

The aim of the present study was to clarify whether subjective sleepiness accurately reflects benzodiazepine-related decline in psychomotor function after taking benzodiazepines (BZPs) in aged people. Subjects were eight healthy, young (mean age, 19.8 years) and seven healthy, older (mean age, 60.9 years) men. Placebo and diazepam (DZP) were administered orally in a single-blind crossover manner to the young subjects (placebo, 5 mg DZP and 10 mg DZP) and to the older subjects (placebo and 5 mg DZP). Plasma drug concentration, choice reaction time (CRT) as an objective measure of psychomotor function, and the Stanford Sleepiness Scale (SSS) as a measure of subjective sleepiness were monitored every 20 min from 1000 until 1600 h, being the drug administered at 1200 h. Pharmacokinetic variables did not differ significantly between the two age groups. DZP at 10 mg in young subjects induced significant increases in both the CRT and SSS score. DZP at 5 mg induced no significant increase in SSS score in either age group but did induce a significant increase in CRT only in the older subjects that matched that in young subjects given 10 mg DZP. The older subjects suffered from dissociation between subjective sleepiness and objective psychomotor impairment under DZP treatment. Such individuals may underestimate the detrimental effects on brain function.

Polypharmacy and the geriatric patient

The older adult population is increasing and with it, the risk of polypharmacy. Multiple physicians treating one patient, increasing comorbidities, and an increase in the variety of drugs available contribute to the adverse effects of polypharmacy on the elderly patient. Application of Beers criteria, appropriate therapeutic drug monitoring, and careful, periodic review of the patient's medication list will assist with preventing the sometimes lethal complications of polypharmacy.

Indiplon: the development of a novel therapy for the treatment of sleep onset and sleep maintenance insomnia

Indiplon is a novel non-benzodiazepine sedative-hypnotic that modulates the GABAA receptor complex. It appears to be more selective for the alpha1-receptor subunit, associated with sedation, than other hypnotics. Two different formulations of indiplon have been developed: an immediate release (IR) version targeting sleep onset insomnia and a modified release (MR) version addressing sleep maintenance insomnia. Early results from clinical trials indicate that both formulations are well tolerated and effective at improving both objective and subjective measures of sleep. As of May 2006 indiplon-IR has been provisionally approved for use in the US market and discussions are continuing with the FDA regarding the MR formulation.

A double-blind, placebo-controlled investigation of the residual psychomotor and cognitive effects of zolpidem-MR in healthy elderly volunteers

AIM

To assess residual psychomotor and cognitive effects of a modified-release formulation of zolpidem (zolpidem-MR), developed to provide sustained hypnotic efficacy during the whole night, compared with placebo and flurazepam.

METHODS

Twenty-four healthy elderly volunteers received four study treatments (zolpidem-MR 6.25 mg and 12.5 mg, placebo and flurazepam 30 mg) using a randomized, cross-over, double-blind design. Residual psychomotor and cognitive effects were assessed with a psychometric test battery. Quality of sleep and residual effects were evaluated subjectively with the Leeds Sleep Evaluation Questionnaire.

RESULTS

Psychometric performance was significantly impaired with flurazepam but not with zolpidem-MR at either dose. Ease of falling asleep and sleep quality were significantly improved with both doses of zolpidem-MR and with flurazepam. Neither active drug modified perception of well-being on awakening.

CONCLUSION

In elderly subjects, zolpidem-MR showed no residual functional impairment in psychometric or cognitive tests sensitive to flurazepam.

Pharmacokinetics and interactions of headache medications, part II: prophylactic treatments

The present part II review highlights pharmacokinetic drug-drug interactions (excluding those of minor severity) of medications used in prophylactic treatment of the main primary headaches (migraine, tension-type and cluster headache). The principles of pharmacokinetics and metabolism, and the interactions of medications for acute treatment are examined in part I. The overall goal of this series of two reviews is to increase the awareness of physicians, primary care providers and specialists regarding pharmacokinetic drug-drug interactions (DDIs) of headache medications. The aim of prophylactic treatment is to reduce the frequency of headache attacks using beta-blockers, calcium-channel blockers, antidepressants, antiepileptics, lithium, serotonin antagonists, corticosteroids and muscle relaxants, which must be taken daily for long periods. During treatment the patient often continues to take symptomatic drugs for the attack, and may need other medications for associated or new-onset illnesses. DDIs can, therefore, occur. As a whole, DDIs of clinical relevance concerning prophylactic drugs are a limited number. Their effects can be prevented by starting the treatment with low dosages, which should be gradually increased depending on response and side effects, while frequently monitoring the patient and plasma levels of other possible coadministered drugs with a narrow therapeutic range. Most headache medications are substrates of CYP2D6 (e.g., beta-blockers, antidepressants) or CYP3A4 (e.g., calcium-channel blockers, selective serotonin re-uptake inhibitors, corticosteroids). The inducers and, especially, the inhibitors of these isoenzymes should be carefully coadministered.

Drug dosage in the elderly: dermatological drugs

Drug pharmacokinetics and pharmacodynamics may be altered in the elderly. An important contribution is made by decreased renal function, but biotransformation in the liver may also play a role. Commonly prescribed dermatological drugs such as methotrexate and cetirizine are likely to be eliminated more slowly in the elderly and potentially hepatotoxic drugs such as itraconazole and acitretin should be used with caution. Altered drug distribution as a result of body composition changes can lead to prolonged half-life or higher plasma concentrations of many drugs. Higher prevalence of adverse drug reactions and multidrug regimens, and large interindividual variability in drug response make drug dosage and administration in the elderly challenging. New immunobiological agents such as alefacept, efalizumab and etanercept, which are approved for treatment of psoriasis, seem to be as well tolerated in the elderly as in younger patients. A recommended approach when prescribing drugs to the elderly would be to start with a small initial dose and to reduce the number of drugs administered simultaneously. It is crucial to simplify the drug regimen as much as possible in order to enhance drug management in the elderly. To improve pharmacotherapy in the elderly, we review age-related changes in pharmacokinetics that are likely to play a role in dermatological practice.

Indiplon: a single compound in two formulations for the treatment of insomnia

Indiplon is a nonbenzodiazepine hypnotic being developed for the treatment of insomnia by Neurocrine Biosciences Inc. It is an allosteric modulator of the γ-amino butyric acid-α receptor complex with very high affinity for the α1 subunit, which is associated with hypnotic activity, sedation and amnesia. Indiplon has been developed in two different formulations: an immediate-release version targeting sleep initiation insomnia and a modified-release version addressing sleep maintenance insomnia. Early results from clinical trials indicate that both formulations are well tolerated and effective at improving objective and subjective measures of sleep.

Sedative and Analgesic Medications: Risk Factors for Delirium and Sleep Disturbances in the Critically Ill

Sedatives and analgesics are routinely used in critically ill patients, although they have the potential for side effects, such as delirium and sleep architecture disruption. Although it should be emphasized that these medications are extremely important in providing patient comfort, health care professionals must also strive to achieve the right balance of sedative and analgesic administration through greater focus on reducing unnecessary or overzealous use. Ongoing clinical trials should help us to understand whether altering the delivery strategy, via daily sedation interruption, or protocolized target-based sedation or changing sedation paradigms to target different central nervous system receptors can affect cognitive outcomes and sleep preservation in our critically ill patients.

The Influence of Cardiovascular Physiology on Dose/Pharmacokinetic and Pharmacokinetic/Pharmacodynamic Relationships

Inter- and intraindividual variability in the relationship between dose and clinical--or pharmacodynamic--response of a drug can be analysed in two steps: firstly, by considering the plasma pharmacokinetic response to a given dose and, secondly, by the connection between both pharmacokinetic and pharmacodynamic responses. As the cardiovascular system is the means of transport of endogenous and exogenous substances, blood flow fraction destined to each organ determines the relative mass of solute in plasma, which is constantly in contact with the tissue. Hence, not only the rate but also the extent of drug transfer would be increased when tissues are irrigated by a higher fraction of cardiac output. Aging and circadian rhythms present similar cardiac output distribution patterns when moving from young to aged adult and from nocturnal to diurnal hours. These two changes lead to an increased blood flow delivery to the extra-splanchnic-renal region in the elderly and in the morning, but with a decreased cardiac output in aged individuals and an increased one during the day. This scenario allows us to forecast substance concentrations outside the blood vessels, which are responsible for the extent of drug elimination and the intensity of drug effect. So available data on disposition and pharmacodynamics of drugs might be explained from another point of view that challenges current knowledge. Furthermore, the administration of cardiovascular active drugs might reverse the chronological sequence between pharmacokinetic and pharmacodynamic responses, since they could modify blood flow distribution.

Psychotropic medications and risk for falls among community-dwelling frail older people: an observational study

BACKGROUND

Injuries due to falls are one of the most important public health concerns for all ages, but especially for frail elderly people. Although a small number of falls have a single cause, the majority have many different causes resulting from the interactions between intrinsic or extrinsic risk factors.

METHODS

We conducted an observational study on data from a large population of community-dwelling elderly people to tests the hypothesis that the current use of different classes of psychotropic medications, including antipsychotic agents, benzodiazepines, nonbenzodiazepine sedative-hypnotics, and antidepressants, increases the risk for falls. We analyzed data from a large collaborative observational study group, the Italian Silver Network Home Care project, that collected data on patients admitted to home care programs (n = 2854).

RESULTS

After adjusting for all potential confounders, users of any psychotropic drugs had an increased risk of fall of nearly 47% (adjusted odds ratio [OR], 1.47; 95% confidence interval [CI], 1.24-1.74). Similarly, compared with nonusers, users of atypical antipsychotic drugs also had an increased risk of falling at least once (OR, 1.45; 95% CI, 1.00-2.11). Among benzodiazepine users, patients taking agents with long elimination half-life (OR, 1.45; 95% CI, 1.00-2.19) and patients taking benzodiazepines with short elimination half-life (OR, 1.32; 95% CI, 1.02-1.72) had an increased risk of falls. Patients taking antidepressants did not show a higher risk of falling compared to nonusers (OR, 0.92; 95% CI, 0.83-1.41).

CONCLUSIONS

Our data suggest that, among psychotropic medications, antipsychotic agents and benzodiazepines are associated with an increased risk of falls. Our findings do not support the hypothesis that preferential prescribing of short-acting benzodiazepines instead of long-acting agents or atypical antipsychotic medications instead of typical agents will substantially decrease fall risk associated with the use of these classes of drugs.

Fecal and urinary excretion of aflatoxin B1 metabolites (AFQ1, AFM1 and AFB-N7-guanine) in young Chinese males

Our study was designed to assess the fecal and urinary excretion of 3 aflatoxin B1 (AFB1) metabolites, aflatoxins M1 (AFM1) and Q1 (AFQ1) and aflatoxin B1-N7-guanine (AFB-N7-guanine) that are produced by the predominant forms of cytochrome P450 enzymes responsible for the biotransformation of AFB1. Fecal and urinary AFM1, AFQ1 and urinary AFB-N7-guanine were assessed in 83 young Chinese males selected from a larger population (n = 300) based on detectable urinary AFM1. The concentration of fecal AFQ1 (median 137 ng/g fresh weight, IQR 9.1 to 450) was approximately 60 times higher than that of AFM1 (2.3 ng/g, IQR 0.0 to 7.3). In urine, the median AFQ1 was 10.4 ng/ml (IQR 3.4 to 23.3), and the median AFM1 and AFB-N7-guanine 0.04 ng/ml (IQR 0.01 to 0.33) and 0.38 ng/ml (IQR 0.0 to 2.15), respectively. A subgroup (n = 14) with hepatitis B virus (HBV) infection had significantly higher fecal concentrations of AFQ1 (p = 0.043) and AFM1 (p = 0.001) than those who were hepatitis B-virus antigen (HBsAg) negative, and the respective differences in urinary AFQ1 and AFM1 concentrations approached statistical significance (p = 0.054, p = 0.138). Our study demonstrates that AFQ1 is excreted in urine and feces at higher levels than AFM1, and feces are an important route of excretion of these AFB1 metabolites. AFQ1 should be further assessed for its predictive value as a marker for exposure and risk of dietary aflatoxins.

Impairment state of cognitive performance and the affecting factors in outpatients following gastrointestinal endoscopy after single-dose diazepam

Diazepam is commonly used as premedicant for endoscopic procedures. Wide interindividual differences have been observed in the residual cognitive effects of the drug after gastrointestinal endoscopy. Our aim was to clarify the major factors, including pharmacokinetic factors, contributing to this wide variation in residual cognitive effect after gastrointestinal endoscopy in the study. Sixty-one outpatients undergoing gastrointestinal endoscopy participated in the study. Cognitive effects were evaluated in the diazepam group (n=52) by the digit symbol substitution test (DSST) twice before and 30 min after an intravenous administration of 5 mg diazepam; in the intervening time gastrointestinal endoscopy was performed. Plasma concentrations of diazepam were determined by HPLC. The control group (n=9) was tested by DSST in the same manner. The cognitive effects according to the change in DSST score was significantly decline in the diazepam group compared with the control group (by 0.2 versus -4.6; P=0.014). This prospective study confirmed that cognition was significantly impaired after gastrointestinal endoscopy by premedication to subjects with 5 mg diazepam. There were very wide variations in change in DSST score. However we could not identify the independent variables that best predicted DSST score difference in a multiple regression analysis for age, plasma albumin level, and plasma diazepam concentration 30 min after intravenous administration. We should pay attention to patients' individual states in cognitive performance following gastrointestinal endoscopy after single-dose diazepam.

Pharmacokinetics in older persons

BACKGROUND

Physiologic changes and disease-related alterations in organ function occur with aging. These changes can affect drug pharmacokinetics in older persons.

OBJECTIVE

This article reviews age-related changes in pharmacokinetics and their clinical relevance.

METHODS

A PubMed search was conducted using the terms elderly and pharmacokinetics. Other reviews were also included for literature searching. The review includes literature in particular from 1990 through April 2004. Some articles from before 1990 were included to help illustrate principles of age-related pharmacokinetics.

RESULTS

There are minor changes in drug absorption with aging. The effect of aging on small-bowel transporter systems is not yet fully established. Bioavailability of highly extracted drugs often is increased with age. Transdermal absorption may be delayed, especially in the case of water-soluble compounds. Fat-soluble drugs may distribute more widely and water-soluble drugs less extensively in older persons. Hepatic drug metabolism shows wide interindividual variation, and in many cases, there is an age-related decline in elimination of metabolized drugs, particularly those eliminated by the cytochrome enzyme system. Any decrement in cytochrome enzyme metabolism appears nonselective. Synthetic conjugation metabolism is less affected by age. Pseudocapillarization of the sinusoidal endothelium in the liver, restricting oxygen diffusion, and the decline in liver size and liver blood flow may influence age-related changes in rate of hepatic metabolism. Frailty, physiological stress, and illness are important predictors of drug metabolism in older individuals. Inhibition of drug metabolism is not altered with aging, but induction is reduced in a minority of studies. Renal drug elimination typically declines with age, commensurate with the fall in creatinine clearance. Renal tubular organic acid transport may decline with age, while the function of the organic base transporter is preserved but may be less responsive to stimulation.

CONCLUSION

Changes in pharmacokinetics occur due to age-related physiologic perturbations. These changes contribute to altered dose requirements in older persons, particularly in the case of drugs eliminated by the kidney. Interindividual variation, disease, frailty, and stress may overshadow age-related changes.

Enhanced heat loss and age-related hypersensitivity to diazepam

Whether elderly people suffer from age-related changes in pharmacokinetics and/or pharmacodynamics with administration of benzodiazepines is still a matter of controversy. We investigated the course of brain function and thermoregulation after oral administration of a standard benzodiazepine, diazepam (DZP), in 8 healthy young men (mean age, 19.8 years; range, 18 to 23 years) and 8 healthy middle-aged and older men (mean age, 60.9 years; range, 53 to 71 years). Placebo or DZP was administered in a single-blind crossover manner to the young men (placebo, 5-mg, 10-mg DZP) and to the older men (placebo, 5-mg DZP), and plasma DZP concentration, choice reaction time, proximal body temperature, and distal body temperature were monitored with high time resolution under a modified constant routine condition to exclude masking effects. Whereas there was no evidence of age-related alterations in pharmacokinetics between the 2 groups, the older subjects, in comparison to the young subjects, showed a more delayed choice reaction time in response to the same plasma DZP level, suggesting that hypersensitivity is related to increased age. DZP at 5 mg in the older subjects induced acute and transient hypothermia to the same degree as that induced by DZP at 10 mg in the young subjects. The distal-proximal body temperature gradient (difference between distal body temperature and proximal body temperature), an indicator of blood flow in distal skin regions, showed strong positive correlation with the delay in choice reaction time in both groups. These findings suggest that hypersensitivity to benzodiazepine in older persons may be due, at least in part, to age-related changes in thermoregulation, especially in the heat loss process.

Comparative pharmacokinetics and pharmacodynamics of short-acting hypnosedatives: zaleplon, zolpidem and zopiclone

Benzodiazepines have historically been the mainstay of treatment for sleeping disorders, yet they have many shortcomings. A new group of sedative hypnotic agents has been developed for this purpose. Similar to the benzodiazepines, zaleplon, zolpidem and zopiclone have activity at the GABA receptor complex, yet they appear to have more selectivity for certain subunits of the GABA receptor. This produces a clinical profile that is more efficacious with fewer side effects. Zaleplon, zolpidem and zopiclone are structurally distinct. Due to variation in binding to the GABA receptor subunits, these three compounds show subtle differences in their effect on sleep stages, and as antiepileptics, anxiolytics and amnestics. The duration of action of zaleplon, zolpidem and zopiclone can be related to their individual pharmacokinetic profile, which subsequently determines the time course of drug effect. Each of these compounds has a unique pharmacokinetic profile with different bioavailability, volume of distribution and elimination half-lives. Zaleplon has a rapid elimination so there are fewer residual side effects after taking a single dose at bedtime. By comparison, zolpidem and zopiclone have a more delayed elimination so there may be a prolonged drug effect. This can result in residual sedation and side effects but may be useful for sustained treatment of insomnia with less waking during the night. There are also differences in potency based on plasma concentrations suggesting that there are differences in binding to the GABA receptor complex. Although zaleplon has a much lower bioavailability (30%), the treatment dose is similar to zolpidem and zopiclone (bioavilaibility of 70%) because of the increased potency of zaleplon. The pharmacokinetics and pharmacodynamics of zaleplon, zolpidem and zopiclone are significantly different from benzodiazepines. The new drugs are sufficiently unique from each other to allow customisation of treatment for various types of insomnia. While zaleplon may be best indicated for the delayed onset of sleep, zolpidem and zopiclone may be better indicated for maintaining a complete night's sleep. Only the patient's symptoms and response to treatment will dictate the best course of treatment.

The effect of age on sildenafil biotransformation in rat and mouse liver microsomes

Sildenafil [SIL (Viagra); Pfizer, New York, NY] is a widely prescribed agent for erectile dysfunction in men older than 65 years. The present study evaluated experimental models to assess age-dependent changes in SIL biotransformation using hepatic microsomes from male rats and mice ranging from 6 weeks to 26 months of age. The role of specific isoforms in the conversion of SIL to its primary circulating metabolite, UK-103,320 (piperazine N-desmethyl sildenafil) in the mouse was also investigated using immunoinhibitory antibodies. Although CYP2C11 largely mediated UK-103,320 formation in the rat, UK-103,320 formation was principally inhibited by a CYP3A antibody in the mouse. An age-related decrement in metabolite formation rate was observed for both species, although this effect was more pronounced in the old rats (reduced to 7% of young) than in the old mice (reduced to 51% of young). CYP2C expression was assessed by Western blot analysis in rat and mouse livers. Age-related differences in hepatic CYP3A expression in the mouse were also compared with metabolite formation rates in the mouse model. Decrements with age in CYP2C and -3A expression in the aging rodents paralleled the decrements in SIL biotransformation, suggesting that age-related differences in SIL metabolic rate may, in part, reflect differences in expression. Although the role of specific CYP enzymes and the clearance values for this reaction may differ among species, age-related changes in these rodent models are consistent with the reduced clearance of SIL observed in human studies.

Cognitive toxicity of drugs used in the elderly

The aged are an extremely heterogeneous population that is growing worldwide, included are healthy and agile individuals in their early sixties, as well as an increasing number of people over the age of 35. Pharmacotherapy is expected to continue its prominent role in the medical management of a wide range of conditions that affect older people. Adverse consequences of all kinds complicate the use of medications, and such events seem to increase in incidence with polypharmacy. Cognitive impairment can occur during the course of treatment with a wide range of medications and can have a variety of presentations, Both the number of concurrent medications that older individuals routinely use and physiologic changes in these patients render them more susceptible to developing cognitive toxicity. Most of the frequently implicated medications carry documentation of their ability to cause cognitive disturbances in their package labeling, suggesting that the level of vigilance for adverse effects during the course of their use should always be high. Such caution can be used to guide appropriate drug treatment of the aged so that clinicians do not need to opt for undertreatment to avoid toxicity.

Defining patterns of benzodiazepine use in older adults

Benzodiazepines are disproportionately prescribed to older adults. Elderly adults with comorbid medical and psychiatric conditions, elderly adults taking multiple medications, and elderly women are the most likely adults to continuously use benzodiazepines. These are also the groups of elderly who are likely to experience adverse effects, including falls, accidents, and motor vehicle crashes. Despite recommendations for short-term treatment and the potential risks of long-term use, some patients continue to receive benefit for extended time periods, occasionally years. Future research needs to be directed at improved identification of which patients will benefit from intermittent versus continuous treatment while minimizing risk for adverse side effects. In order to advance the study of the risks and benefits of benzodiazepine use, we have proposed a set of definitions for classification of use. These definitions can be used to develop clinical guidelines based on empirically derived clinical research models.

Race but not age affects erythromycin breath test results in older hypertensive men

Erythromycin breath tests (ERBT) were performed to determine age and racial effects on CYP3A4-mediated hepatic clearance in hypertensive men (n = 43) in the clinical setting. Older hypertensive African American men (n = 19: 71 +/- 8 years, mean +/- SD) had faster ERBT clearance compared with Caucasian (n = 20: 72 +/- 6 years) hypertensive men (at 20 minutes after dosing: 0.042 +/- 0.01 percent dose/min exhaled vs. 0.033 +/- 0.013; at 60 minutes after dosing: 0.030 +/- 0.05 vs. 0.023 +/- 0.007 percent dose/min exhaled; ANOVA, p = 0.007), while age, smoking, and reported alcohol intake did not affect ERBT. The data suggest faster hepatic CYP3A-mediated clearance in African American men compared with Caucasian men, and that race may significantly affect CYP3A-mediated hepatic clearance in patients treated for hypertension.

Midazolam sedation for upper gastrointestinal endoscopy in older persons: a randomized, double-blind, placebo-controlled study

OBJECTIVES

To investigate the benefits and risks of using midazolam for sedation during upper gastrointestinal endoscopic procedures in older persons.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

A 304-bed geriatric university hospital.

PATIENTS

Sixty-five geriatric inpatients (mean age 84 +/- 7) undergoing gastroscopy.

INTERVENTION

Sedation with either midazolam (30 microg/kg IV) or saline (placebo). All patients received supplemental oxygen during the procedure (2 L/minute).

MEASUREMENTS AND RESULTS

Patients' recall of their tolerance to the exam (categorical scale) and pain score were significantly in favor of midazolam at 2 and 24 hours. Multivariate analysis at 2 hours showed that midazolam increased the probability of good tolerance (odds ratio (OR) = 19.3; 95% confidence interval (CI) 2.2-170.4, P = .008). Circumstantial amnesia occurred at 24 hours in 84% (midazolam) versus 27% (placebo) (P < .001). With midazolam, mean sedation time was 83 +/- 13 minutes and mean arterial pressure (MAP) was about 10 mm Hg lower without clinically significant hypotension. Hypoxemia (SaO2 < 92%) was more frequent in the midazolam group after endoscopy (44% vs. 18%, P = .033), but no major desaturation was observed. Cognitive function (Mini-Mental State Exam, MMSE) was similar before and 2 and 24 hours after the exam in both groups. Acute confusion was observed in two patients (1 midazolam, 1 placebo). In multivariate analysis, midazolam was associated with a higher risk of hypoxemia after endoscopy (OR = 3.5; 95% CI 1.1-10.8, P = .029) but not of confusion.

CONCLUSIONS

Under adequate surveillance, the benefits in terms of tolerance to the procedure of low-dose midazolam for upper gastrointestinal endoscopic sedation outweigh the risks in older people.

Oxidative and nonoxidative benzodiazepines and the risk of femur fracture. The Systematic Assessment of Geriatric Drug Use Via Epidemiology Study Group

Benzodiazepine use is a well-identified risk factor for falls and the resulting femur fractures in elderly adults. Benzodiazepines not requiring hepatic biotransformation may be safer than agents undergoing oxidation because oxidative activity has been shown to decline with age. The association between the use of either oxidative or nonoxidative benzodiazepines and the risk of femur fracture among elderly adults living in nursing homes was studied. A nested case-control study was conducted using the Systematic Assessment of Geriatric drug use via Epidemiology (SAGE) database; the records of 9,752 patients hospitalized for incident femur fracture during the period 1992 to 1996 were extracted, matching by age, gender, state, and index date to the records of 38,564 control patients. Conditional logistic regression models were conducted to estimate the odds ratios (ORs) for femur fracture with adjustment for potential confounders. The adjusted OR for the overall use of benzodiazepines was 1.10 (95% confidence interval [CI], 0.98-1.20); the risk seemed of only slightly greater magnitude for exposure to nonoxidative agents (1.18; 95% CI, 1.03-1.36) than to oxidative benzodiazepines (1.08; 95% CI, 0.95-1.23). Among the latter, the effect was mainly accounted for by the use of agents with a long elimination half-life. A dose relationship was observed exclusively among users of long half-life oxidative benzodiazepines. The risk associated with the use of nonoxidative benzodiazepines showed no relationship to the age of the patients. In contrast, patients aged 85 years or older receiving oxidative benzodiazepines at high dosages or as needed had a two- to three-fold increased risk of femur fracture than did patients in the younger age group. Among older individuals, the use of benzodiazepines slightly increased the risk of femur fracture, mainly irrespective of the metabolic fate of the drug. Our results suggest that the use of nonoxidative benzodiazepines does not carry a lower risk for femur fracture than does the use of oxidative benzodiazepines. However, the latter agents may be associated with a somewhat higher risk of side effects among the oldest old, especially at higher dosages.

A double-blind comparison of lorazepam and oxazepam in psychomotor retardation and mutism

BACKGROUND

An increasing number of case reports indicate a superior therapeutic response of catatonialike symptoms, such as severe psychomotor disturbance and mutism, associated with psychiatric disorder to the benzodiazepine lorazepam (LO). Equivocal results, however, are also reported with regard to other benzodiazepines for the treatment of this syndrome. The purpose of this study was to compare the effects of LO and oxazepam (OX), benzodiazepines with comparable pharmacokinetics, on psychomotor retardation and mutism associated with psychiatric disorder.

METHODS

Twenty-one hospitalized patients with severe psychomotor retardation and mutism were treated with 2 mg LO and 60 mg OX in a double-blind crossover study design.

RESULTS

Both benzodiazepines significantly reduced psychomotor symptoms. When administered for the first time, 4 of 7 patients with LO and 6 of 10 patients with OX improved at least 50% on visual analog scale (VAS) rating. Reduction in symptoms was significant with LO and OX treatment on either day of treatment. The second time, however, LO was significantly better compared with OX in alleviating the target symptoms.

CONCLUSIONS

Both OX and LO are effective for the treatment of psychomotor retardation. Thus, the beneficial effect of LO on psychomotor retardation and mutism is not a unique pharmacodynamic property but more likely due to its pharmacokinetic profile. The differential effect of the two benzodiazepines on the second day of treatment warrants further clarification. Several hypotheses are evaluated.

Pharmacokinetics and the pharmacodynamic action of midazolam in young and elderly patients undergoing tooth extraction

OBJECTIVE

To determine whether age-dependent pharmacokinetic and pharmacodynamic alterations account for a more pronounced response to benzodiazepines among elderly patients.

METHODS

Twelve young patients and 10 elderly patients received an intravenous dose of 0.05 or 0.03 mg/kg midazolan, respectively, before third molar extraction. Postoperative pain was treated with 30 mg dihydrocodeine. Serum concentrations of midazolam and sedative effects were monitored with visual analog scales and choice reaction time measurements for 6 hours. Test values above baseline were integrated, and pharmacokinetic-pharmacodynamic analysis was performed. Heart rate, blood pressure, arterial oxygen saturation, and amnesia also were assessed.

RESULTS

There were no significant age-dependent differences in disposition of midazolam between young and elderly patients (apparent volume of distribution, 1.3 +/- 0.2 versus 1.1 +/- 0.4 L/kg; halflife, 3.3 +/- 1.5 hours versus 3.7 +/- 2.2 hours; total body clearance, 451 +/- 186 ml/min versus 343 +/- 137 ml/min). However, higher values of area under the effect curve (AUEC) and AUEC divided by area under the serum concentration-time curve (AUC) (sensitivity index) were observed among the elderly as follows: AUEC for reaction time (AUECRT) (573 versus 261; p = 0.042), AUEC for visual analog scale (AUECVAS) (37.7 versus 14.4; p = 0.011), AUECRT/AUC (6.3 versus 1.8; p = 0.007), and AUECVAS/AUC (0.40 versus 0.11; p = 0.009) compared with the young group. Likewise, mean concentration at half-maximal effect for sedation was lower (p = 0.025) among older patients (20.5 +/- 2.2 ng/ml) than among younger (29.7 +/- 6.6 ng/ml) patients. Amnesia was observed among 86% of patients and oxygen saturation was always 95% or more of basal value. There were no age-related differences in concentration of dihydrocodeine and its active metabolite dihydromorphine, but dihydromorphone levels were much lower in there intermediate metabolizers (455 to 879 fmol/l) and especially in five poor metabolizers (65 to 498 fmol/L) than among extensive metabolizer of cytochrome p450 2D6 (1604 to 6490 fmol/L).

CONCLUSION

Elderly patients are more sensitive to the sedative action of midazolam than young patients, and the sensitivity is caused by age-dependent pharmacodynamic alterations. The age-adjusted doses used are both effective (for sedative amnesia) and safe (in terms of arterial oxygen saturation, heart rate, and blood pressure.

Correlates and prevalence of benzodiazepine use in community-dwelling elderly

OBJECTIVE

To describe the prevalence of benzodiazepine use, sociodemographic and physical health factors associated with use, dosages taken, and directions for use among individuals aged 65 years and older.

DESIGN

Cross-sectional analysis of baseline data from the community-based, prospective observational Cardiovascular Health Study.

PATIENTS/PARTICIPANTS

Medicare eligibility lists from four U.S. communities were used to recruit a representative sample of 5,201 community-dwelling elderly, of which 5,181 participants met all study criteria.

MEASUREMENTS AND MAIN RESULTS

Among participants, 511 (9.9%) were taking at least one benzodiazepine, primarily anxiolytics (73%). Benzodiazepines were often prescribed to be taken pro re nata (PRN "as needed"), and 36.5% of prescriptions with instructions to be taken regularly were taken at a dose lower than prescribed. Reported over-the-counter (OTC) sleep aid medication use was 39.2% in benzodiazepine users and 3.3% in nonusers. In a multivariate logistic model, the significant independent correlates of benzodiazepine use were being white (odds ratio [OR] 1.9; 95% confidence interval [CI] 1.0, 3.4), female (OR 1.7; CI 1.4, 2.2), and living in Forsyth County, North Carolina, or Washington County, Maryland, compared with living in Sacramento County, California, or Allegheny County, Pennsylvania (OR 2.3; CI 1.4, 2.2); having coronary heart disease (OR 1.6; CI 1.2, 2.1), health status reported as poor or fair (OR 1.8; CI 1.4, 2.3), self-reported diagnosis of nervous or emotional disorder (OR 6.7; CI 5.1, 8.7), and reporting use of an OTC sleep aid medication (OR 18.7; CI 14.1, 24.7).

CONCLUSIONS

One in 10 participants reported taking a benzodiazepine, most frequently an anxiolytic, often at a lower dose than prescribed and usually PRN. The high prevalence of OTC sleep aid medication and benzodiazepine use may place the patient at increased risk of psychomotor impairment. Physicians should assess OTC sleep aid medication use when prescribing benzodiazepines.

Pharmacokinetics of alprazolam in elderly patients with multiple diseases

The pharmacokinetics of alprazolam (1 mg p.o.) were investigated (using a new developed HPLC-assay) in 10 multimorbid elderly patients (five female, five male; mean age 72.8 +/- 8.2 years, creatinine clearance 63.6 +/- 25.9 ml/min, weight 68.9 +/- 13.9 kg). Compared with young and elderly volunteers from other studies peak plasma concentrations of alprazolam were decreased while peak time and elimination half-life were increased. 'Second peak' plasma levels (correlated with age and creatinine clearance) occurred in eight of 10 elderly patients. The variability associated with the pharmacokinetic parameters in the multimorbid elderly patients was far greater than that observed in young and old healthy volunteers. Mean alprazolam concentrations in multimorbid patients aged 72 years or more were elevated as compared to 'younger' patients (age range: 63-71 years). Dose reduction should be considered in the older multimorbid patients.

Factors related to current and subsequent psychotropic drug use in an elderly cohort

AIMS OF THE STUDY

The purpose of this study was to estimate the prevalence of psychotropic drug use in a cohort of elderly persons and to examine factors related to current and subsequent drug use.

POPULATION

A representative cohort of non-institutionalized subjects aged 65 and over living in New Haven, Connecticut, was interviewed in 1982, and again in 1985 and 1988. Psychotropic drug use during the prior two weeks was assessed at each home interview.

RESULTS

At the baseline interview in 1982, 12.3% of the subjects reported using psychotropic drugs, half of them (6.25%) benzodiazepines. In multivariate analyses, psychotropic drug use was significantly associated with female gender and white ethnicity but not with older age. Psychotropic drug use and depressive symptomatology were strongly correlated in both genders. However, less than 5% of the subjects reporting high depressive symptomatology were using antidepressants. Psychotropic drug use was also associated with sleep problems in men and medical conditions in women. Psychotropic drug consumption increased slightly to 15.1% in 1988. Continuous use (use reported in 1982, 1985 and 1988) was found in 4.5% of the sample; it was strongly related to both depressive symptomatology and sleep problems reported at baseline. New use, beginning either in 1985 or in 1988, was observed in 12.6% of the sample; it was related to female gender, older age, and, among baseline health variables, to depressive symptomatology.

CONCLUSIONS

Prevalence of psychotropic drug use in this cohort of elderly people was lower than in other studies conducted in the U.S. The reasons for this variation are discussed. Continuous use was not higher for benzodiazepines than for other psychotropic drugs.

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.

Benzodiazepine use among elderly patients presenting at the emergency room

This study evaluated the prevalence of benzodiazepine intake by elderly patients presenting at the emergency room of a university hospital. Of 388 patients, 42.5% used one or more benzodiazepine (BZD) drugs in the week prior to admission. There were significantly more women among the BZD users (P < 0.05). Mean duration of intake was long (62 months), but daily dosage was adjusted to age. Of the BZD using patients, 27% took a BZD with long elimination half life. No relationship was found between the BZD intake and the occurrence of falls. Fallers were significantly older (P = 0.019) and were more often women (P = 0.046).

Pharmacokinetic optimisation of drug therapy in elderly patients

With increasing age, there are a number of physiological changes that affect the handling of drugs in the human body. Increases in body fat percentage as well as decreases in lean body mass, hepatic metabolism and renal elimination capacity are of particular clinical significance. It is important to take these changes into account when choosing drug therapy for older patients in order to minimise adverse effects and maximise potential benefits. This is particularly important when prescribing drugs with a narrow therapeutic index such as digoxin, theophylline, phenytoin, lidocaine (lignocaine) or warfarin. When available, monitoring of plasma concentrations can assist in the optimisation of drug dosage.

Pharmacotherapy of insomnia: practice and prospects

Insomnia is a complex complaint which is often multifactorial in origin. Pharmacotherapy can only be an adjunct in the treatment of insomnia and hypnotics should be given on an intermittent basis for short periods of time. An overview is presented of the currently available hypnotics, of which benzodiazepines are still the most widely prescribed. New drugs which bind to specific receptor subtypes or which are partial benzodiazepine receptor agonists might overcome the disadvantages associated with chronic benzodiazepine use, but more long-term investigations are needed.

Aging increases pharmacodynamic sensitivity to the hypnotic effects of midazolam

The effect of aging on the pharmacodynamics of midazolam was investigated in a double-blinded study involving 39 consenting patients ranging in age from 39 to 77 yr. Midazolam was infused intravenously (i.v.) using a pharmacokinetic model-driven drug infusion device to achieve a plasma midazolam concentration that was held constant for the 10-min duration of the study. Blood samples were obtained from the radial artery at 5 and 10 min for subsequent measurement of the plasma midazolam concentrations. With the 10-min sample, the patients were also assessed for the presence or absence of responsiveness to verbal command. To ensure that the pharmacodynamic end-point was assessed under the condition of a relative steady-state effect-site midazolam concentration, only those patients (n = 33) in whom the plasma midazolam concentration at 10 min was within 30% of the measured concentration at 5 min were included in the subsequent data analyses. Logistic regression was used to fit the verbal command response/no response data to a mathematical model that included patient age and the plasma midazolam concentration measured at 10 min. Cp50, the steady-state plasma midazolam concentration at which 50% of patients would be expected not to respond to a specific stimulus (e.g., verbal command), was calculated as a function of age from the parameterized logistic model. The midazolam Cp50 for response to verbal command decreased significantly (P = 0.034) with increasing patient age, demonstrating that aging increases pharmacodynamic sensitivity to the hypnotic effects of midazolam independent of pharmacokinetic factors.