Dysregulation of neurosteroids in obsessive compulsive disorder

Alterations in hormone concentrations, including adrenocorticotropin, corticotropin releasing hormone, and cortisol have been reported in patients with obsessive compulsive disorder (OCD). Dehydroepiandrosterone (DHEA) and its sulfated metabolite, DHEA-S, have not been assessed in patients with OCD. We report 24-h serum DHEA, DHEA-S, and cortisol concentrations in a young man with OCD and 15 healthy young men. Circadian patterns of DHEA and cortisol were markedly different in the subject with OCD than in the control subjects. DHEA and DHEA-S concentrations were substantially higher in the OCD subject than in the control subjects. In contrast, cortisol concentrations were similar in the OCD subject and the control subjects. Future clinical studies are needed to evaluate the significance of DHEA and DHEA-S in OCD.

Endogenous concentrations of DHEA and DHEA-S decrease with remission of depression in older adults

BACKGROUND

Clinical studies of endogenous concentrations of dehydroepiandrosterone (DHEA) and its sulfated conjugate DHEA-S in depression are limited. This study was designed to evaluate the influence of successful pharmacological treatment of late-life depression on concentrations of DHEA, DHEA-S and cortisol.

METHODS

We determined endogenous concentrations of DHEA, DHEA-S and cortisol in elderly control subjects (n = 16) and in elderly depressed patients who remitted (n = 44) or failed to remit (n = 16) with pharmacological treatment. Depressed patients were treated for 12 weeks with either nortriptyline or paroxetine.

RESULTS

In remitters, DHEA and DHEA-S concentrations were lower at week 12 than at week 0 (p =.002 and p =.0001, respectively). In the nonremitters and control subjects, neither DHEA nor DHEA-S concentrations changed. Decreases in hormone concentrations were associated with improvement in mood and functioning in depressed patients. Although cortisol concentrations decreased in remitters and nonremitters, the change was not significant.

CONCLUSIONS

Our data suggest that the decrease in DHEA and DHEA-S in remitters is related to remission of depression rather than to a direct drug effect on steroids, as nonremitters had no change in hormone concentrations.

Dehydroepiandrosterone, dehydroepiandrosterone-sulfate, and cortisol concentrations in intensive care unit patients

STUDY OBJECTIVE

This purpose of this study was to determine whether severity of illness, as defined by the intensive care unit (ICU) admission APACHE II (updated Acute Physiology and Chronic Health Evaluation) score, is correlated with early morning cortisol, dehydroepiandrosterone (DHEA), and/or dehydroepiandrosterone-sulfate (DHEA-S) concentrations.

DESIGN

Early morning concentrations of DHEA, DHEA-S, and cortisol were determined within 24 hrs of admission and compared with admission APACHE II scores.

SETTING

Medical (MICU), neurologic (NICU), and surgical (SICU) intensive care units of the University of Pittsburgh Medical Center.

PATIENTS

A total of 191 men and women ranging in age from 16 to 93 yrs. All had been admitted to an ICU.

MEASUREMENTS AND MAIN RESULTS

Statistically significant correlations between APACHE II scores and cortisol were observed for women in the MICU and SICU (r = .68, p = .0001; r = .35 p = .017, respectively) and for men in the NICU (r = .55, p = .003) and the SICU (r = .29, p = .036). The correlations between APACHE II scores and DHEA concentration data were statistically significant for women in the MICU (r = .37, p = .047) and SICU (r = .43, p = .002), as was the correlation between APACHE II and DHEA-S concentrations among women in the SICU (r = .38, p = .008). Although not statistically significant, a similar relationship was observed in the smaller group of NICU women (r = .40, p = .099). Each correlation was essentially unchanged when adjusted for age.

CONCLUSION

These data show a positive correlation between APACHE II and cortisol concentrations in all groups except the MICU men. Also evident is the positive correlation between APACHE II scores and DHEA and DHEA-S concentrations in women, but not in men.

Sex differences in the pharmacokinetics of dehydroepiandrosterone (DHEA) after single- and multiple-dose administration in healthy older adults

The pharmacokinetics of exogenously administered DHEA have not been well characterized despite its increasing use in therapeutic and research investigations. The purpose of this study was to evaluate the pharmacokinetics of DHEA and its sulfated metabolite (DHEA-S) after single- and multiple-dose oral administration of DHEA 200 mg. Healthy older adult volunteers (7 women, 6 men) ages 65 to 79 years were studied on five visits separated by 1 week. Subjects received daily administration of placebo (days 1 to 7), DHEA 200 mg (days 8 to 22), and placebo (days 23 to 29). Blood samples were collected over 24 hours on days 1, 8, 15, 22, and 29 for DHEA and DHEA-S determinations by RIA. Pharmacokinetic parameter estimates were calculated by noncompartmental methods. Administration of DHEA 200 mg resulted in higher DHEA Cmax, AUC, and overall concentrations in women than in men (p < 0.03); DHEA-S parameter estimates were similar between men and women. Following a single dose of DHEA 200 mg, DHEA concentrations increased 5- to 6-fold in both men and women, and DHEA-S concentrations increased 5-fold in men and 21-fold in women relative to endogenous concentrations. The results of this study indicate that the pharmacokinetics of DHEA differ between older men and women.

Clonazepam and sertraline: absence of drug interaction in a multiple-dose study

Thirteen subjects (seven men, six women) completed a placebo-controlled, randomized, double-blind, crossover study to determine whether an interaction occurs between clonazepam and sertraline. Ten days of once-daily doses of either clonazepam 1 mg and placebo (CZ + PL) or clonazepam 1 mg and sertraline 100 mg (CZ + SR) were administered; there was an 11-day washout period. Sertraline did not significantly affect the pharmacokinetics of clonazepam (p > 0.13). Clonazepam apparent oral clearance, volume of distribution, and half-life were 3.9 +/- 0.2 L/hr, 233 +/-11 L, and 40.5 +/- 0.3 hours, respectively. The kinetics of the inactive metabolite 7-aminoclonazepam were marginally affected by sertraline, with a 21% decrease in the elimination half-life (p = 0.03) relative to CZ + PL and no significant difference between treatments in area under the curve or metabolite ratio. Card sorting (CS), digit-symbol substitution test (DSST), nurse-rated sedation scale (NRSS), and self-rated sedation scores were assessed four times daily on days -1 (PL + PL), 1, 4, 7, and 10. There were no differences between treatments in area under the effect curve or maximum observed effect for CS, DSST, or NRSS. Maximum impairment on all assessment days was low, with a less than 10% change from the drug-free values for CS and DSST. Despite higher clonazepam concentrations, predose (time 0) psychomotor and sedation scores did not differ among days -1, 1, 4, 7, and 10 or between treatments. These results in healthy volunteers indicate that sertraline does not affect the pharmacokinetics or pharmacodynamics of clonazepam.

DHEA and DHEA-S: a review

Dehydroepiandrosterone (DHEA) and its sulfated metabolite DHEA-S are endogenous hormones secreted by the adrenal cortex in response to adrenocorticotrophin (ACTH). Much has been published regarding potential effects on various systems. Despite the identification of DHEA and DHEA-S more than 50 years ago, there is still considerable controversy as to their biological significance. This article reviews the metabolism and physiology of DHEA and DHEA-S, the influence of age and gender on concentrations, and changes in endogenous concentrations associated with disease states and other factors, including diet and exercise. This article is unique in that it also summarizes the influence of drugs on DHEA and DHEA-S concentrations, as well as concentrations of DHEA and DHEA-S observed after the administration of DHEA by various routes. Sections of the article specifically address DHEA and DHEA-S concentrations as they relate to stress, central nervous system function and psychiatric disorders, insulin sensitivity, immunological function, and cardiovascular disorders.

Alprazolam increases dehydroepiandrosterone concentrations

The gamma-aminobutyric acid (GABA) agonist alprazolam is known to decrease adrenocorticotropic hormone and cortisol concentrations. Dehydroepiandrosterone (DHEA) is secreted synchronously with cortisol by the adrenal glands and demonstrates diurnal variation. The major objective of this study was to determine whether alprazolam affects concentrations of DHEA and DHEA-S, the sulfated metabolite. In vitro studies have demonstrated that DHEA-S, and perhaps DHEA, have GABA antagonistic activity. Another objective was to determine whether DHEA-S and/or DHEA concentrations are related to psychomotor impairment after alprazolam. Thirty-eight healthy volunteers (25 young men, aged 22-35, and 13 elderly men, aged 65-75) received a single intravenous dose of alprazolam 2 mg/2 min (part 1). Fifteen young and 13 elderly men responded to alprazolam and agreed to participate in part 2 of the study, which was a crossover of placebo and alprazolam infusion to plateau for 9 hours. Plasma samples at 0, 1, 4, and 7 hours were assayed for steroid concentrations. Alprazolam produced (1) significant increases in DHEA concentrations at 7 hours in both young and elderly men; (2) significant decreases in cortisol concentrations; and (3) no change in DHEA-S concentrations. The relationship between psychomotor decrement and DHEA concentrations at 7 hours after alprazolam 2 mg/2 min was described by a u-shaped curve (p < 0.0047). Both the linear and quadratic components of the equations for the tests were significant (p < 0.002). These results suggest that alprazolam modulates peripheral concentrations of DHEA and that DHEA and/or DHEA-S may have an in vivo role in modulating GABA receptor-mediated responses.

Simplified procedure for measurement of serum dehydroepiandrosterone and its sulfate with gas chromatography-ion trap mass spectrometry and selected reaction monitoring

Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) are endogenous steroids that have recently been widely publicized as potential treatments for many disorders. This paper describes a gas chromatographic-ion trap mass spectrophotometric assay with selected reaction monitoring for measurement of DHEA and DHEAS levels. The hormones and internal standard (5-androsten-3beta-ol-16-one methyl ester) are extracted from serum with Oasis solid-phase extraction tubes. The extracted steroids are dissolved in methanol and injected into a Finnigan GCQ ion trap mass spectrometer. In the selected reaction mode, both DHEA and DHEAS can be identified and quantified in a single injection. No derivatization or expensive deuterated internal standards are required.

Do alprazolam-induced changes in saccadic eye movement and psychomotor function follow the same time course?

The purpose of this study was to determine whether short-term tolerance develops to GABA-agonist-induced changes in saccadic eye movements (SEMs), and whether the time course for GABA-agonist induced onset and offset of impairment is similar for SEMs and for psychomotor function. An additional goal was to determine whether there are differences in sensitivity between SEMs and psychomotor function. Six healthy volunteers participated in this balanced double-blind, three-way crossover, single-dose study of placebo and two different dosage forms of the GABA-agonist alprazolam: a rapidly absorbed oral 1.5-mg compressed tablet (CT) and a 3.0-mg sustained release (SR) tablet. Treatments were separated by a 7-day washout period. Peak concentrations did not differ between CT and SR treatments, although area under the concentration-time curve (AUC) of alprazolam was greater after administration of SR than after CT, because plateau concentrations were attained after SR. Both SEM and psychomotor tests showed time-dependent responses consistent with the development of tolerance. SEMs discriminated the differences in rate of drug input of the CT and SR formulations, with impairment evident at low concentrations during absorption. SEM impairment also persisted longer than did psychomotor impairment. Peak saccade velocity is a more sensitive indicator of pharmacologic effects mediated by the GABA-benzodiazepine receptor complex than are psychomotor responses. This is probably the result of the very high GABA dependency of SEMs, along with their limited sensitivity to motivation.

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.

Alprazolam in young and elderly men: sensitivity and tolerance to psychomotor, sedative and memory effects

This study was designed to determine whether age influences sensitivity to alprazolam and/or rate of acute tolerance development to the effects of alprazolam. Three treatments were each separated by 4 weeks. Twenty-five young (ages 22-35) and 13 elderly (ages 65-75) men received 2 mg of alprazolam/2 min i.v. Blood samples were obtained over 48 hr, and sedative, psychomotor and memory effects were assessed serially for 12 hr. Clearance was lower (P = .05) and elimination t[1/2] was longer (P = .005) in the elderly, but area under the concentration curve to 12 hr and maximum concentration did not differ by age group. Maximum impairment was greater in the elderly for all assessments. Mean EC50 values differed between the elderly (25.3 and 25.0 ng/ml) and the young (39.8 and 36.5 ng/ml) on card sorting and digit symbol substitution, respectively (P < .001). Bolus treatment data were used to individualize doses for the crossover of placebo and alprazolam; infusions were designed to maintain a plateau alprazolam concentration between 1 and 9 hr. Alprazolam concentrations through 12 hr did not differ between the young and elderly. Median t[1/2] for offset of effect for digit symbol substitution was 2.8 hr in the young and 4.9 hr in the elderly (P = .05). Therefore, aging decreases alprazolam clearance and increases sensitivity to effects of alprazolam through a mechanism other than pharmacokinetics; aging also decreases the rate of offset of effect of alprazolam. In addition, the data provide insight into the intensity of initial effect as a determinant of rate of tolerance development.

Adverse effects of risperidone on eye movement activity: a comparison of risperidone and haloperidol in antipsychotic-naive schizophrenic patients

Risperidone is a novel and clinically effective atypical antipsychotic medication with a unique biochemical profile. To contrast the neurophysiological effects of this new medication with those of a typical antipsychotic medication, we performed quantitative measurements of saccadic eye movements in a series of antipsychotic-naive schizophrenic patients treated with either risperidone or haloperidol. Patients were tested before and after 1 month of treatment, and a matched group of healthy subjects was tested twice over a similar time interval. Risperidone, but not haloperidol, was associated with prolonged latency and decreased peak velocity and accuracy of saccadic eye movements that was detectable 4 weeks after treatment initiation. The adverse effects of risperidone may be due to the lack of development of acute tolerance to its powerful serotonergic (5-HT2A) antagonism, which could be responsible for the disruption of brainstem physiology in regions controlling saccadic eye movements.

Progesterone: does it affect response to drug?

This article presents an overview of the gamma-aminobutyric acid (GABA)-benzodiazepine receptor complex (GBRC) and its in vitro modulation by THP, a metabolite of progesterone, as well as the results of a single-dose study of progesterone and triazolam in 16 post-menopausal women. The study results indicate that a 300 mg oral dose of progesterone administered 2.5 hours prior to a challenge dose of triazolam significantly increases sensitivity to triazolam: concentration values required for 50 percent of maximum effect (EC50) decreased by 20 to 32 percent after pre-treatment with progesterone. These data support the In vitro findings that THP enhances binding of benzodiazepines to the GBRC. The full clinical implications of these data, including extensions to other steroids, need to be explored.

Oral administration of micronized progesterone: a review and more experience

Historically, oral progesterone has been regarded clinically ineffective because of its poor absorption and rapid clearance. Recent evidence suggests that an oral micronized form of natural progesterone is readily absorbed, produces luteal phase serum concentrations, provokes an end-organ response, and has no detrimental effect on the lipoprotein profile. Thus it is considered by many to be an attractive alternative to synthetic progestin. We evaluated the effects of a single oral dose of micronized progesterone 300 mg in eight healthy postmenopausal women. The maximum serum concentration ranged from 15.72-625.98 ng/ml. The extent of absorption increased with increasing age. The reviewed literature and our data indicate considerable intersubject variability in the extent of progesterone absorbed after administration of oral micronized progesterone.

Coadministration of nefazodone and benzodiazepines: II. A pharmacokinetic interaction study with triazolam

This study was conducted to determine the potential for an interaction between nefazodone, a new antidepressant, and triazolam after a single dose of triazolam and multiple doses of nefazodone in a randomized, double-blind, placebo-controlled study in healthy male volunteers. The metabolism of triazolam is dependent on cytochrome P450 3A4, and because nefazodone has been shown in vitro to be an inhibitor of this isoenzyme, this study was conducted to assess the potential for an interaction between the two drugs. Twelve subjects were assigned to one of two groups and received an oral dose of either placebo or 0.25 mg of triazolam on days 1 and 2. Nefazodone (200 mg) was administered twice daily from the evening of day 2 to the morning of day 9. Subjects received either 0.25 mg of triazolam or placebo with the nefazodone dose on the mornings of days 8 and 9. Serial blood samples were collected on the mornings of days 1, 2, 8, and 9 for the analysis of triazolam by a validated gas chromatography/electron capture detection method and on days 8 and 9 for the analysis of nefazodone and its metabolites, hydroxynefazodone (HO-nefazodone) and m-chlorophenylpiperazine (mCPP), by a validated high-performance liquid chromatography/ultraviolet method. Noncompartmental pharmacokinetic analysis showed that there was no effect of triazolam on the pharmacokinetics of nefazodone, HO-nefazodone, or mCPP after the coadministration of triazolam and nefazodone. There was a significant effect of 200 mg of nefazodone twice daily on the pharmacokinetics of triazolam. Mean triazolam peak concentration values increased (p = 0.003) from 2.33 to 3.88 ng/ml when triazolam was administered alone and in combination with nefazodone, respectively. Corresponding mean triazolam area under the curve values increased (p < 0.001) from 8.14 to 31.74 ng.h/ml. The plasma protein binding of triazolam was approximately 85% when triazolam was given alone and when given concurrently with nefazodone. The increase in triazolam concentrations in plasma appears to be attributable to the inhibition of cytochrome P450 3A4 metabolism by nefazodone. If triazolam is coadministered with nefazodone, a reduction in the triazolam dosage is recommended; no dosage adjustment is required for nefazodone.

Coadministration of nefazodone and benzodiazepines: I. Pharmacodynamic assessment

One hundred two healthy men were evaluated in one of three studies conducted to evaluate the coadministration of nefazodone, 200 mg twice daily, and three benzodiazepines: triazolam, 0.25 mg; alprazolam, 1 mg twice daily; or lorazepam, 2 mg twice daily. In the first study, psychomotor performance, memory, and sedation were assessed at 0, 0.5, 1.5, 2.5, and 9 hours after single doses of triazolam alone and again after 7 days of nefazodone. Data from 6 of 12 subjects in this study were evaluable because of a dosing error in the other 6 subjects. In the subsequent two parallel design studies, groups of 12 volunteers received 7 days of either placebo; nefazodone, 200 mg; alprazolam, 1 mg twice daily; or alprazolam plus nefazodone or, in the second study, either placebo; nefazodone; lorazepam, 2 mg twice daily; or lorazepam plus nefazodone; the studies were identical, double-dummy, double-blind designs. Psychomotor performance, memory, and sedation were assessed at 0, 1, 3, and 8 hours after the 8 a.m. dose on days 1, 3, 5, and 7 of the studies. In all studies, blood samples were also obtained at testing times so that effect/concentration comparisons could be made and so full pharmacokinetic analyses could be done for separate studies. Nefazodone had no effect on psychomotor performance, memory, or sedation relative to placebo in any study. The mean maximum observed effect (MaxOE) on psychomotor performance and sedation were increased when triazolam was given after 7 days of nefazodone (p < 0.05); also, triazolam concentration was 60% higher at this time. Alprazolam and lorazepam impaired performance on day 1 (mean MaxOE, 34 and 30%, respectively) relative to placebo and nefazodone. By day 7 of alprazolam or lorazepam, psychomotor impairment decreased, indicating the development of tolerance. Alprazolam plus nefazodone increased psychomotor impairment (MaxOE, approximately 50%) and sedation relative to alprazolam alone on days 3, 5, and 7 (p < 0.05). Higher alprazolam concentrations explained the increased impairment in the alprazolam plus nefazodone treatment group; however, it is also possible that there was a delay in the development of tolerance. There were no differences in psychomotor impairment, memory, sedation, or lorazepam concentration detected between the lorazepam alone and lorazepam plus nefazodone treatments. This is consistent with the absence of a pharmacokinetic interaction between nefazodone and lorazepam. These results indicate that if the coadministration of a benzodiazepine is required in patients receiving nefazodone therapy, clinically significant interactions would be less likely with those eliminated by conjugative metabolism such as lorazepam. In cases where a benzodiazepine eliminated by oxidative metabolism is required, a reduction in initial dosage and careful clinical evaluation for signs of psychomotor impairment may be appropriate.

Effect of neuroactive steroids on [3H]flumazenil binding to the GABAA receptor complex in vitro

Modulation of benzodiazepine receptor ligand binding to the GABAA receptor complex by the neuroactive steroids 3 alpha-hydroxy-dihydroprogesterone (3 alpha-OH-DHP) and 3 alpha-hydroxycorticosterone (3 alpha- THDOC) was assessed in an in vitro binding assay with the benzodiazepine antagonist [3H]flumazenil using rat cortical membranes. Neuroactive steroids, pentobarbital, GABA and bicuculline did not significantly affect flumazenil binding. However, the addition of neuroactive steroids significantly decreased the Ki of benzodiazepine agonists, including alprazolam, diazepam and clonazepam, indicating an increase in agonist affinity. Only the addition of 3 beta-OH-DHP, an inactive stereoisomer had no effect on the Ki of these agonists. The binding of the benzodiazepine inverse agonist FG 7142 was not significantly affected by these steroids, but the addition of GABA significantly increased the Ki of FG 7142 indicating a decrease in inverse agonist affinity. High concentrations of GABA or bicuculline were able to occlude the 3 alpha-THDOC mediated decrease in alprasolam Ki, indicating a GABA dependent mechanism of binding enhancement. An advantage of using [3H]flumazenil is that neither the Ki nor the Bmax change in the presence of allosteric site modulators, permitting the simple and direct assessment of alterations in benzodiazepine ligand affinity for the GABAA receptor complex by neuroactive steroids.

Triazolam pharmacokinetics after intravenous, oral, and sublingual administration

This study was designed to evaluate the relative and absolute bioavailability of triazolam, 0.25 mg, after the administration of the marketed oral tablet and a sublingual prototype wafer; an intravenous dose was used as a reference. Twelve men were evaluated in a three-way crossover study; study days were separated by 1 week. A single dose was administered to each subject at approximately 8 a.m.; serial blood samples were obtained for the determination of triazolam concentration. The fraction absorbed relative to intravenous was 20% higher in the sublingual than in the oral treatment (p = 0.0128); the difference between treatments was greatest in the first 2 hours as indicated by the area under the curve from 0 to 2 hours (p < 0.05). The extraction ratio ranged from 0.05 to 0.25, and the predicted availability after oral administration was 86% with a range of 75 to 95%. In contrast, the observed mean absolute availability was 44% (oral) and 53% (sublingual). A potential explanation for this discrepancy between predicted and observed bioavailability is that after oral administration, a fraction of triazolam may be metabolized by cytochrome P450IIIA4 in the gut wall, with a separate fraction subject to first-pass metabolism in the liver. Although this study was not designed to identify sites of triazolam metabolism, the proposed explanation is consistent with the occurrence of P450IIIA4 in the stomach, small intestine, and liver. Doses administered sublingually avoid first-pass metabolism, producing earlier and higher peak concentrations than do doses administered orally.

Time-dependent sensitization to triazolam? An observation in three studies

Evidence of time-dependent sensitization (TDS) to triazolam was observed in three separate clinical studies. Study 1 was conducted in 12 normal-weight and 12 obese men; an intravenous bolus dose of triazolam, 0.5 mg, was administered on two occasions. Study 2 was a balanced crossover of three 0.25-mg oral doses and one 0.20-mg oral dose of triazolam in 11 men. Study 3 was a balanced crossover of one placebo, one 0.5-mg, and two 0.4-mg oral doses of triazolam. In all three studies, treatments were separated by 6 days and included serial blood sampling for characterization of pharmacokinetics. Psychomotor response was assessed with the Digit Symbol Substitution Test and the Continuous Performance Test (CPT). Sedation was rated by an observer. For each measure, an effect ratio was calculated as the area under the effect curve divided by the area under the triazolam concentration curve; this parameter relates the extent of response relative to drug concentration in plasma. Effect ratios increased progressively by week for CPT; the percentage increase ranged from 31.9% in the study 1 normal subjects (week 1 to week 2; p = 0.08) to 631% in study 2 (week 1 to week 4; p = 0.0013). Similar increases were observed for other responses. Overall, the effect ratio data demonstrate increasing responsiveness per unit of triazolam concentration when triazolam was administered as a single dose at 1-week intervals. This observation was incidental to the original objectives of the studies. However, the data suggest that definitive studies to verify the occurrence of this phenomenon need to be conducted.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics and pharmacodynamics of triazolam after two intermittent doses in obese and normal-weight men

This study was designed to determine whether differences in alpha-1 acid glycoprotein and free drug concentrations result in an altered response to triazolam. Twelve normal-weight and 12 obese adult male subjects received intravenous doses of triazolam, 0.5 mg, on two occasions separated by 1 week. There was a small difference in the alpha-1 acid glycoprotein concentrations between groups but no difference in free fraction of triazolam. There was a longer terminal half-life (t1/2 beta) in the obese subjects (3.16 +/- 0.87 vs. 3.83 +/- 1.24, p = 0.0098). Overall, week 1 data revealed no difference in effect between normal and obese subjects. However, response data reveal a pattern of increased sensitivity with the second exposure to triazolam. For example, area under the effect curve (AUEC) on all tests was significantly greater in week 2 for both groups of subjects. For a memory test and sedation from 0 to 12 hours, AUEC/free AUC ratios were significantly greater in week 2 for all subjects. The obese had a higher ratio on week 2 than on week 1 for all psychomotor tests and sedation (0 to 4.5 hours; p < 0.05). The results of modeling psychomotor impairment-concentration data pooled by group for each week continue the pattern: week 1 data are similar between the obese and normal-weight subjects. Although EC50 values are up to 15% lower in week 2 for the normal-weight subjects, EC50 values are as much as 66% lower in week 2 for the obese, where a lower EC50 indicates greater sensitivity. Logistic regression of the recognition data is consistent with these results.(ABSTRACT TRUNCATED AT 250 WORDS)

Orally administered progesterone enhances sensitivity to triazolam in postmenopausal women

An endogenously formed metabolite of progesterone, 3 alpha-hydroxy-5 alpha-dihydroprogesterone (3 alpha-OH-5 alpha-DHP) modulates the gamma-aminobutyric acid receptor complex and plays a physiologic role in brain excitability regulation. On the basis of in vitro observations of 3 alpha-OH-5 alpha-DHP-enhanced [3H]flunitrazepam binding, we investigated the potential clinical effect of coadministering oral progesterone and triazolam. Sixteen postmenopausal women were randomly assigned to receive either intravenous triazolam plus oral progesterone 300 mg (TRZPROG) or intravenous triazolam plus oral placebo (TRZ). Triazolam was infused until 0.5 mg was given or until a predetermined maximal response was attained. Pharmacodynamic evaluation included DSST, continuous performance test, hand-eye coordination, short-term memory, and sedation. Effect ratios were calculated as the ratio of area under the effect-time curve to area under the curve (AUC). Variants of the sigmoid Emax model were fit to the data from the three psychomotor performance tests. A triazolam dose of less than 0.5 mg was administered to seven of eight subjects in the TRZPROG and five of eight subjects in the TRZ group, resulting in lower triazolam AUC values for the TRZPROG than for the TRZ group (p = 0.0275). There was clear evidence for a pharmacodynamic interaction. Mean effect ratios for all tests were greater in the TRZPROG group than in the TRZ group (DSST, p = 0.0097; continuous performance test, p = 0.0338; hand-eye coordination, p = 0.0041). The TRZPROG group had lower EC50 values than the TRZ group (DSST, p = 0.0435; continuous performance test, p = 0.0381; hand-eye coordination, p = 0.0154).(ABSTRACT TRUNCATED AT 250 WORDS)

Design and pharmacodynamic evaluation of novel dual release formulations of triazolam

Triazolam is an effective hypnotic that can cause amnesia and psychomotor performance decrements, particularly after a 0.5 mg dose. Previous pharmacodynamic studies suggested a relationship between these effects and triazolam plasma concentration. A novel dual release bilayer tablet was designed to mimic the onset of action of a 0.25 mg dose and to maintain the duration of a 0.5 mg dose without the side effects associated with the 0.5 mg dose. The immediate release component of the bilayer tablet contained 0.25 mg triazolam while the sustained release component contained 0.15 mg triazolam. Two prototype formulations of the bilayer tablet, differing in rate of release in the sustained release component, were tested against a conventional 0.5 mg triazolam compressed tablet and placebo in a single-dose, double-blind, four-way crossover study in healthy male subjects. Triazolam plasma concentration time profile was obtained over 12 hours following single administration of each treatment. Effects of triazolam on central nervous system function were evaluated using psychomotor performance tests, immediate and delayed recall tests and rating of sedation. The triazolam plasma concentrations were not significantly different among the active drug treatments, although the dual release tablets did give the expected profiles. There were significant differences in triazolam effects on memory and psychomotor performance. The slowest releasing dual-release tablet showed significantly less psychomotor impairment and memory deficit than the conventional tablet. There was no difference in sedation among the active drug treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of [3H]flunitrazepam binding by natural and synthetic progestational agents

Progesterone is metabolized by ring-A reduction with subsequent oxidoreduction to 3 alpha-hydroxy-5 alpha-dihydroprogesterone (3 alpha-OH-5 alpha-DHP), a naturally occurring metabolite that has been shown to enhance [3H]flunitrazepam ([3H]FNZ) binding. Medroxyprogesterone acetate (MPA), a commonly prescribed progestational agent, is a synthetic progesterone derivative that has a metabolic profile similar to that of progesterone. In this study, the effects of MPA and its ring-A reduced metabolites DHMPA and THMPA on [3H]FNZ binding were investigated. While known modulators of specific [3H]FNZ binding demonstrated expected effects in frozen and fresh rat cortical tissue, 3 alpha-OH-5 alpha-DHP enhanced [3H]FNZ binding only in fresh, not frozen, tissue. Neither DHMPA nor THMPA affected binding, while MPA partially inhibited [3H]FNZ binding by 40%. In addition, five test drugs were used to assess the effect of gender and hormonal status on [3H]FNZ binding. Neither gender nor hormonal status influenced binding. Thus, ring-A reduced metabolites of progesterone but not of MPA enhance [3H]FNZ binding. The clinical implications of these in vitro results are currently under investigation.

Acute tolerance to triazolam during continuous and step infusions: estimation of the effect offset rate constant

Although acute tolerance to selected effects of many benzodiazepines is known to occur, acute tolerance to triazolam has not been documented even in studies that have included pharmacodynamic modeling. The purpose of this investigation was to determine whether acute tolerance to triazolam occurs in humans. Intravenous bolus doses of triazolam were used to individualize two subsequent intravenous infusions: one to achieve and maintain a constant triazolam concentration and one to achieve a series of incremental steady-state concentrations; a placebo treatment was also included. Ten healthy men completed the four single-dose treatments. Serial blood sampling and psychomotor and memory testing were done. In the constant infusion treatment, mean performance impairment was greatest at 1 h and then decreased rapidly despite maintenance of a mean triazolam concentration of 2.48 ng/ml for 9 h. Neither learning nor changes in free concentration account for the observations. Additionally, data from the step-infusion treatment indicate that the triazolam effect-concentration relationship after a single dose can be altered by rate of administration. Because tolerance develops, the administration of drug in small increments results in an increased effect at a lower concentration, with a blunted maximal response. Furthermore, our data suggest intersubject variability in the rate of development of acute tolerance. Patients who develop tolerance more slowly would experience a longer duration of effect. Further study regarding the rate of development of tolerance to specific effects and in different patient populations is warranted.

Alprazolam in end-stage renal disease. II. Pharmacodynamics

The sensitivity to the psychomotor and memory effects of alprazolam was evaluated in 12 normal subjects and 12 dialysis patients (seven patients receiving hemodialysis and five patients receiving continuous ambulatory peritoneal dialysis). Subjects received a single oral dose of 0.5 mg alprazolam, 2 mg alprazolam, and placebo in a double-blind, placebo-controlled, balanced, three-way crossover study with a Latin square design. After administration of the test drug, blood was obtained for alprazolam concentration and protein-binding determinations, and psychomotor performance, memory, and sedation were assessed. The maximum psychomotor impairment corrected for free alprazolam concentration was 5.0%, 8.2%, and 10.1% per nanogram per milliliter in normal subjects, patients receiving hemodialysis, and patients receiving continuous ambulatory peritoneal dialysis, respectively (p less than 0.01), after administration of 2 mg alprazolam. Free alprazolam concentrations at which 50% of maximum effect is elicited for psychomotor impairment were 10, 7.40, and 5.31 ng/ml in normal subjects, patients receiving hemodialysis, and patients receiving continuous ambulatory peritoneal dialysis, respectively. The maximum memory impairment corrected for the maximum free alprazolam concentration was 4.4%, 7.2%, and 8.9% per nanogram per milliliter, respectively (p less than 0.09), after administration of 2 mg alprazolam. Thus our group of patients receiving dialysis showed enhanced sensitivity to some psychomotor and memory effects of alprazolam.

New high-performance liquid chromatographic method for the determination of alprazolam and its metabolites in serum: instability of 4-hydroxyalprazolam

A high-performance liquid chromatographic method was developed for the determination of alprazolam (ALP) and its active metabolites, alpha-hydroxyalprazolam (AOH) and 4-hydroxyalprazolam (4OH) in human serum. During assay development, the instability of 4OH was revealed. Factors affecting stability of 4OH were then investigated. In this report, the assay methodology for the determination of ALP and AOH, the instability of 4OH, subsequent interference of 4OH breakdown products with AOH quantification, and factors affecting 4OH stability are described. The clinical significance of our findings are reported.

Comparison of adinazolam pharmacokinetics and effects in healthy and cirrhotic subjects

The pharmacokinetics and pharmacodynamics of adinazolam were investigated in six patients with cirrhosis and six sex-matched control subjects. These subjects received a single 30-mg oral dose of adinazolam mesylate. Serial blood samples were collected for 24 hours after drug administration. Plasma was assayed for adinazolam and mono-desmethyl-adinazolam (NDMAD) concentrations by a specific HPLC technique. Pharmacokinetic parameters were estimated by noncompartmental methods. Psychomotor effects of adinazolam were assessed using a digit-symbol substitution test (DSST) and aiming test (AIM). Memory effects were assessed by a modification of the Randt memory test (MEM); sedation was assessed using an observer-rated scale. Differences in pharmacokinetics of the parent drug were noted: adinazolam oral clearance was lower in patients with cirrhosis (35.0 +/- 27.9 L/hr) than in normal subjects (73.7 +/- 22.1 L/hr; P = .024); Kel was significantly lower in patients with cirrhosis (.126 +/- .084 vs. .278 +/- .070; P = .007), whereas the mean t1/2 in patients with cirrhosis was 7.70 hours as compared with 2.67 hours in normal subjects. Cmax was higher in the group with cirrhosis (266 +/- 95.5 vs. 153 +/- 29.3 ng/mL; P = .019). For NDMAD, Kel was lower in cirrhotic subjects and resulted in a prolonged t1/2 in cirrhotic subjects compared with normal subjects (6.70 vs. 3.79 hr; P = .0152). NDMAD AUC tended to be higher in cirrhotic subjects (1515 +/- 254 vs. 1162 +/- 254 ng.hr/mL; P = .064). No significant differences were noted in psychomotor performance, memory, or sedation.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprazolam in end-stage renal disease: I. Pharmacokinetics

In a double-blind, randomized, placebo-controlled study, the pharmacokinetics of alprazolam and its active metabolite, alpha-hydroxyalprazolam, were determined in 12 normal subjects and 12 dialysis patients [7 hemodialysis (HD) patients and 5 continuous ambulatory peritoneal dialysis (CAPD) patients]. Blood samples were collected over 48 hours after alprazolam 0.5 mg and alprazolam 2 mg administration. Alprazolam and alpha-hydroxyalprazolam concentrations and alprazolam free fraction were determined. The pharmacokinetics of alprazolam were similar in normal subjects and HD patients with the exception of higher free fraction in HD patients. Differences were detected, however, in the pharmacokinetics of alprazolam in CAPD patients when compared with normal subjects and HD patients. These differences included a higher free fraction and a lower apparent oral clearance and free clearance in CAPD patients than in normal subjects or in HD patients. There was also a tendency for a later Tmax and a longer elimination half-life in CAPD patients than in normal subjects or HD patients. Alpha-hydroxyalprazolam concentrations were less than 15% of corresponding alprazolam concentrations in normal subjects and dialysis patients. Thus, end-stage renal disease is associated with changes in absorption, distribution, and/or elimination of alprazolam.

Alprazolam in the elderly: pharmacokinetics and pharmacodynamics during multiple dosing

Previous studies have suggested that elderly men eliminate alprazolam more slowly than young adults. This study in the elderly was designed to determine whether a change in pharmacokinetics influences the response to alprazolam during multiple dose regimens. In addition, the study was designed to determine alprazolam pharmacokinetics and the degree to which its hydroxymetabolites accumulate, the degree of psychomotor impairment, and whether tolerance to impairment and sedation develops during three different multiple dose regimens. Twenty-six subjects completed this study. The subjects were randomized into one of three treatment groups: 0.25 mg q8h, 0.5 mg q8h, and 2 mg q12h. Subjects remained in the clinic for 8 days (day -2-day 5). Day 0 was used as a drug free testing day to establish baseline scores for sedation, digit symbol substitution (DSS), card sorting (CS) tasks, and two computer tests. Subjects received the drug according to schedule on days 1 through 4, with day 5 as the washout day. Blood samples were assayed for alprazolam, alpha-hydroxyalprazolam and 4-hydroxyalprazolam. Alpha-hydroxyalprazolam concentrations were below assay detection limits in all subjects in the 0.25 and 0.5 mg q8h groups and less than or equal to 2.6 ng/ml in the 2 mg q12h group. When detectable, 4-hydroxyalprazolam concentrations were less than 10% of the corresponding alprazolam concentration. Mean alprazolam oral clearance values in the three treatment groups ranged between 0.54 and 0.62 ml/min/kg and half-lives were in excess of 21 h. Degree of sedation and impairment was dose related. Sedation and impairment was not higher on day 4 despite concentrations 2-3 times as great as on day 1, indicating development of tolerance. Subjects were not, however, back to baseline level of performance on day 4.

Pharmacokinetics of the newer benzodiazepines

The assay methods used to determine the concentrations of the newer benzodiazepines include electron-capture gas-liquid chromatography, high performance liquid chromatography with ultraviolet detection, gas chromatography-mass spectrometry, radioassay and radioreceptor assay. The method used frequently is the highly sensitive and specific electron-capture gas-liquid chromatography. Other methods are associated with limitations. The triazolo- and imidazolebenzodiazepines differ structurally from the 'classical' benzodiazepines such as diazepam, and offer distinct differences in pharmacological activity and in time-course of effect. Alprazolam and triazolam, both 1,4-triazolobenzodiazepines, have high affinities for the benzodiazepine receptor as do midazolam and loprazolam, which are 1,4-imidazolebenzodiazepines. Absorption is characteristically rapid, with peak alprazolam and triazolam concentrations occurring within 1 hour after oral administration. Sublingual administration results in peak alprazolam and triazolam concentrations that are higher and occur earlier than with the oral route. The volume of distribution of alprazolam and triazolam is approximately 1L. Alprazolam is 70% bound to plasma proteins and the extent of binding is independent of concentration. Similarly, triazolam is approximately 85% bound to plasma proteins, variability in binding being explained by variations in alpha 1-acid glycoprotein concentration. The 1,4-triazolo ring prevents the oxidative metabolism of the classical benzodiazepines which results in formation of active metabolites with long elimination half-lives. Alprazolam is extensively metabolised: 29 metabolites have been identified in the urine, and its major metabolite, alpha-hydroxyalprazolam, has pharmacological activity. alpha-Hydroxyalprazolam and 4-hydroxyalprazolam are detectable in plasma in amounts which account for less than 10% of the administered dose. Mean alprazolam elimination half-life in healthy adult subjects ranges from 9.5 to 12 hours; liver disease prolongs alprazolam elimination, but renal insufficiency does not. Triazolam also undergoes oxidation and subsequent glucuronidation. alpha-Hydroxytriazolam is the major metabolite, in addition to which 4-hydroxyalprazolam and alpha-4-hydroxytriazolam have been identified in plasma and urine. The elimination half-life of triazolam ranges between 1.8 and 5.9 hours, while that of the conjugated metabolites is short, approximately 3.8 hours. Accumulation of triazolam or its metabolites after multiple doses does not occur. Liver disease prolongs triazolam elimination from the body, but renal disease does not.(ABSTRACT TRUNCATED AT 400 WORDS)

Tolerance to alprazolam after intravenous bolus and continuous infusion: psychomotor and EEG effects

A study was undertaken to compare the time course of changes in psychomotor performance and spectral edge (SE) of the EEG and to relate these changes to alprazolam concentrations in a pharmacokinetic/pharmacodynamic tolerance model. Digit symbol substitution (DSS) tests were administered and EEG data were obtained for SE calculation in a four-way crossover study in four normal men. Each treatment consisted of a 2-minute bolus injection followed by an 8-hour infusion. Treatment A, placebo, consisted of a 50% propylene glycol injection followed by a saline infusion. Active drug treatments were: B, 0.5 mg alprazolam plus saline infusion; C, 2.0 mg alprazolam plus saline; and D, 1.0 mg plus 72 micrograms alprazolam/hr for a total dose of 1.576 mg in 8 hours. For both DSS and SE data, three distinct effect-concentration curves result from the three alprazolam treatments, with successive shifts to the right as dose increases. A tolerance rate constant (kt) of 0.15 hr-1 was calculated from the DSS vs. time data during the 8 hour alprazolam infusion. The Hill equation was altered by using kt in an exponential modification of EC50. The resulting tolerance model describes both DSS and SE vs. concentration data from the rapid-injection and continuous-infusion treatments.

Pharmacodynamics of triazolam after intravenous administration

Triazolam pharmacokinetics and effects on sedation, short-term amnesia, and psychomotor performance were evaluated in 25 normal volunteers as part of a safety and tolerance study of intravenous dosing of triazolam. Triazolam kinetics were linear after intravenous administration of doses up to 1.0 mg with no differences among doses in elimination half-life, volume of distribution, or clearance. The hepatic extraction ratio ranged from 0.14 to 0.37, suggesting that triazolam should undergo moderate first-pass metabolism after oral administration. The duration and extent of sedation, decrement in psychomotor performance test scores, and amnesia were dose related, but all subjects returned to baseline alertness and function within eight hours of dosing. The time-course of effects on memory and psychomotor performance were related to triazolam plasma concentration profile using an Emax model for effect and a two-compartment pharmacokinetic model. The probability of a subject being asleep was related to triazolam plasma concentrations using logistic regression. These models indicate that intravenous doses of 0.25 to 0.5 mg triazolam would be effective for use preoperatively for short surgical procedures.

Pentoxifylline in end-stage renal disease

Little information is available about the clearance of pentoxifylline and its metabolites in renal failure. Consequently, when a dialysis patient required this drug, we started at a low dose and gradually increased the dosage while monitoring the patient for signs or symptoms of toxicity and following plasma concentrations of parent drug and its metabolites. Our patient appeared to develop evidence of drug toxicity after about six days on two-thirds of the usual recommended adult dose of the drug. The pentoxifylline half-life and apparent half-life of metabolite I were both substantially prolonged as compared with data from healthy volunteers. Both accumulated rapidly in plasma. Concentrations of metabolites IV and V were also very high.

Nighttime dosing of triazolam in patients with liver disease and normal subjects: kinetics and daytime effects

This study was designed to determine whether the severity of liver dysfunction in cirrhosis affects the kinetics and next-day effects of triazolam after bedtime administration of a single oral dose. Eight patients with biopsy-proven cirrhosis and seven normal subjects matched for age, weight, and sex participated as paid volunteers. The first night was the control night, when no nighttime sedative was administered. The next day, psychomotor testing was performed at 8:30 AM, 2 PM, and 5 PM. Triazolam 0.25 mg was administered at 10:30 PM that evening. Psychomotor testing was repeated on the posttriazolam day in the same manner as on the control day. Blood samples were obtained from a venous catheter at 11 predetermined times in the 14 hours after triazolam administration. Memory testing was also performed. Apparent oral clearance of triazolam was directly related to albumin concentration and indocyanine-green elimination rate constant, and inversely related to partial thromboplastin time expressed as seconds over control. Clearance was 6.69 +/- 2.52 mL/min/kg in the normal subjects and 4.99 +/- 3.14 in the subjects with cirrhosis. There were no significant differences in Cmax between normal subjects (1.43 +/- 0.44 ng/mL) and subjects with cirrhosis (1.62 +/- 0.31 ng/mL) or in tmax (2.0 +/- 1.0 vs 2.5 +/- 1.9 hr) between normal and cirrhosis subjects, respectively. Posttriazolam, cirrhotic subjects took significantly longer to sort cards at 8:30 AM than on the control day. There was a significant correlation between extent of impairment on 8:30 AM card sorting by suit and AUC0-8 (r = 0.687; P = 0.0046).(ABSTRACT TRUNCATED AT 250 WORDS)

The clinical pharmacist in drug research and development. An academic-industrial center

The center for Pharmacodynamic Research represents a novel approach to academic-industrial research agreements that may be a useful model for others to pursue. It is designed to take advantage of the strengths of the company and the university in order to enhance the research conducted and to provide benefits to both. At the same time, it takes into account the responsibility of the university to provide graduate education and the need of industry for scientists in the future. The center was only recently established, however, and must be considered work in progress. Although it has been successful to this point, its value will only be established by longevity and productivity. We have every confidence that it will prove to be a valuable experiment.

Influence of dosing regimen on alprazolam and metabolite serum concentrations and tolerance to sedative and psychomotor effects

The relationships between alprazolam and metabolite concentrations and CNS effects were determined in a double-blind placebo controlled four-way crossover trial in 16 normal male volunteers. Active drug treatments consisted of 4-day regimens of 4 mg alprazolam PO daily as 2 mg bid., 1 mg qid, and 0.25 mg each hour. On days 1 and 4, the kinetics, sedative and psychomotor effects were evaluated. Plasma concentrations of the 4- and alpha-hydroxy metabolites of alprazolam were less than 10% of unchanged alprazolam levels on both days. Accumulation of these metabolites and alprazolam was dependent on alprazolam half-life (11.6 h). Acute and chronic tolerance to the sedative and psychomotor effects was observed with all active drug treatments. All alprazolam treatments resulted in significantly greater sedation than placebo on days 1 and 4. However, on day 4, sedation was 16-36% less than observed on day 1, despite plasma concentrations 1.4-2.76 times the day 1 concentrations. Sedation from alprazolam was reduced in each successive study phase, suggesting a tolerance which was sustained during the 10-day washout between phases. By day 4, psychomotor performance was not different from placebo, indicating more complete development of tolerance than occurred for the sedative effect. Sedation and psychomotor impairment on day 1 were greatest with 2 mg alprazolam bid. During the initiation of therapy, the patient will likely experience less sedation and psychomotor impairment with smaller, more frequent doses. Since tolerance develops to these effects, the advantage of more frequent dosing regimen dissipates by the 4th day.

Mechanism for the interaction between triazolam and cimetidine

Four normal volunteers each received three intraduodenal infusions of 0.5 mg triazolam solutions. Three treatments were: a pH 2.3 solution in which 47 per cent of the dose had hydrolysed to form a triazolo-benzophenone (TB); a pH 6.0 solution containing negligible TB; the pH 6.0 solution administered during cimetidine treatment (1200 mg day-1). TB was stable in serum and only very low TB serum concentrations were observed from the pH 2.3 treatment. No difference was observed in any triazolam pharmacokinetic parameter between the pH 6.0 and the pH 2.3 treatments. Cimetidine increased the triazolam AUC infinity and Cmax by 54 and 35 per cent, respectively. These results indicate that TB undergoes extensive presystemic conversion to triazolam and the triazolam-cimetidine interaction occurs primarily through a reduction in triazolam clearance.

Single-dose pharmacokinetics of clomiphene citrate in normal volunteers

Twenty-four healthy adult female volunteers participated in a randomized, three-phase double-blind crossover trial comparing the single-dose (50 mg) pharmacokinetics of three formulations of clomiphene citrate (CC). Plasma levels of both the Z(cis) and E(trans) isomers of CC, as well as principal metabolites, were determined at periodic intervals; and no differences between formulations were observed. The active Z isomer attained peak blood levels later than the inactive E isomer and was eliminated much more slowly, significant plasma concentrations still being detected up to 1 month after treatment. The results of this study demonstrate that three commercially available formulations of CC are bioequivalent.

Temporal variation in triazolam pharmacokinetics and pharmacodynamics after oral administration

The effect of time of day of drug administration on triazolam pharmacokinetics was studied in ten healthy men. In a randomized, two-way, crossover investigation, each subject received one 0.5 mg triazolam tablet either in the morning (7 AM) or evening (10 PM). Blood samples were obtained immediately before dosing and at selected times up to 12 hours after dosing. Triazolam plasma concentrations were determined by gas chromatography with electron capture detection. Psychomotor performance tests, including digit symbol substitution, card sorting by suits, and card sorting by fours, were administered, and the subjects' sedation was rated before drug and at two, ten, and 12 hours after drug administration. In addition, anterograde amnesia was assessed by showing objects to subjects two hours after dosing and testing aided and unaided recall at ten hours following administration. Triazolam's apparent elimination half-life after evening administration was significantly longer than after daytime ingestion (3.77 hr vs. 2.94 hr, P less than .05). There was no difference between times of dosing in total oral clearance or apparent volume of distribution. The absorption of triazolam was slower after evening administration, with an absorption half-life of 21.9 vs 13.3 minutes after daytime dosing. Performance decrements were significantly greater two hours after dosing in evening than in the daytime, but anterograde amnesia was more pronounced after daytime dosing. There was no effect on psychomotor performance at ten or 12 hours after administration in daytime or evening. These results indicate temporal variation in triazolam absorption and elimination.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacodynamic evaluation of the benzodiazepine-oral contraceptive interaction

The sedative, psychomotor, and memory effects of single oral doses of alprazolam (ALP), lorazepam (LOR), temazepam (TMP), and triazolam (TRZ) were evaluated in women taking oral contraceptives (OCs) and a comparable group of control women. Nine women taking OCs and 11 control women took doses of 1 mg ALP and 2 mg LOR and 10 OC users and 10 control women took 30 mg TMP and 0.5 mg TRZ on two occasions separated by 28 days. Minimal psychomotor impairment was noted after TMP. ALP, LOR, and TRZ produced greater performance impairment in the OC users. Correcting the maximum observed performance decrement for plasma concentration did not account for the differences between OC users and controls. After TMP, there was less sedation during the first 2 hours in OC users, who also had higher plasma TMP clearance. There were no differences in sedation between OC users and controls after ALP, LOR, and TRZ; however, there was less than 50% power to detect a 30% difference. Amnestic effects in OC users and controls did not differ after any of the four drugs. The observed patterns of anterograde amnesia were different, with the earliest and most pronounced recognition failure after TRZ (50% at 1.5 hours), while the LOR effect increased to a maximum (30%) 4 hours after dosing. Our data suggest that differences in benzodiazepine pharmacokinetics between OC users and control women do not account for observed differences in psychomotor impairment. Women taking OCs are more sensitive to the psychomotor effects of single oral doses of benzodiazepines.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of end stage renal disease and aluminium hydroxide on triazolam pharmacokinetics

Triazolam 0.5 mg was administered to 11 dialysis patients and 11 age, weight and sex matched controls. Peak plasma concentrations (Cmax) were higher in control subjects, but there were no other differences between the groups. When dialysis patients took triazolam with 3600 mg aluminum hydroxide suspension, Cmax and AUC were increased into the range observed in control subjects. It appears that triazolam can be used at normal doses in patients with renal dysfunction, without regard to interaction with aluminum hydroxide gel, or to alterations in elimination.

Effects of end-stage renal disease and aluminum hydroxide on temazepam kinetics

The kinetics of temazepam, 30 mg, were evaluated in 11 patients with end-stage renal disease. Age ranged from 18 to 65 years. On two occasions separated by 1 week, single oral 30 mg doses of temazepam were given once with water (TM) and once with 3600 mg aluminum hydroxide gel (TM + AHG). There were no significant differences in the maximum plasma concentration, the time to reach maximum concentration, or elimination rates between TM and TM + AHG dosing. In approximately half the subjects there were secondary temazepam peak concentrations. In the remaining subjects, temazepam elimination was biphasic, with the terminal t1/2 ranging from 11 to 77 hours. There was a lag time before absorption in all subjects. The percent free temazepam in plasma from dialysis subjects ranged from 4.4% to 8.8% (mean = 5.9%). Compared with literature reports of subjects with normal renal function, the maximum plasma concentration was lower and the percent free temazepam was higher in dialysis subjects. When sedation score was plotted against plasma temazepam concentration, there was clockwise hysteresis consistent with tolerance or adaptation to effects of the drug. Thus aluminum hydroxide gel does not affect temazepam absorption. The clinical significance of the low plasma concentrations and high free temazepam fraction in dialysis subjects is uncertain.

Effect of oral contraceptives on triazolam, temazepam, alprazolam, and lorazepam kinetics

The effects of low-dose estrogen oral contraceptives (OC) on the elimination of the oxidized benzodiazepines triazolam (TRZ) and alprazolam (ALP) and the conjugated benzodiazepines temazepam (TMZ) and lorazepam (LOR) were studied in two parallel crossover studies of 20 women each. Women taking OC steroids containing low doses of estrogen and women matched for age, weight, and cigarette smoking received single oral doses of TRZ (0.5 mg) and TMZ (30 mg) or ALP (1 mg) and LOR (2 mg). Kinetics were determined as plasma concentrations during 48 hr after dosing. OCs inhibited the metabolism of ALP: The AUC increased and the elimination rate constant was greater in users of OCs. For TRZ, which has an intermediate extraction ratio, the AUC was increased by OCs but not significantly so. In contrast, OCs decreased the AUC for TMZ and the elimination rate constants for LOR and TMZ. The AUC of LOR was not affected by OCs. Low-dose estrogen OCs may therefore inhibit the metabolism of some oxidized benzodiazepines and accelerate the metabolism of some conjugated benzodiazepines.

Incidence of next-day anterograde amnesia caused by flurazepam hydrochloride and triazolam

The incidence of next-day anterograde amnesia was evaluated in hospitalized patients who received flurazepam hydrochloride or triazolam. A blinded observer assessed memory and daytime drowsiness in 154 patients after the bedtime ingestion of flurazepam hydrochloride (n = 54), triazolam (n = 49), or no hypnotic drug (n = 51). The hypnotic agents were administered before midnight. At approximately 0800 the next morning, the patients were shown a picture of an object on colored construction paper and asked to remember it as well as the color of the background. Both the observer and patient assessed drowsiness using the Stanford Sleepiness Scale. The observer also made a note of the items on the patient's breakfast tray. Patients were then revisited at 1100 and asked to recall the object in the picture, the color of the background, and at least three items from their breakfast tray. Ten of the 54 patients in the flurazepam group failed to recall all three items compared with only two in the triazolam group and two in the control group. The 14 patients who experienced memory impairment were significantly more drowsy at 0800 than those who were able to recall the items. Next-day anterograde amnesia occurred more frequently in patients who received flurazepam hydrochloride than in those who received triazolam or no hypnotic drug. This effect may be related to the next-day drowsiness caused by flurazepam and its slowly eliminated active metabolite.

Triazolam protein binding and correlation with alpha-1 acid glycoprotein concentration

On two occasions separated by a minimum of 1 wk, plasma was obtained from 12 patients (aged 18 to 73 yr) on dialysis after an overnight fast. Samples were assayed for albumin and alpha 1-acid glycoprotein (AGP) concentrations. 14C-Triazolam was added to each sample to a final concentration of 5 ng/ml. Protein binding was determined by equilibrium dialysis. Unbound triazolam ranged from 6.4% to 15.4% (mean = 10.0%). AGP concentrations ranged from 71.8 to 205.1 mg% (mean = 123.4 mg%). Triazolam binding ratio (bound/unbound concentration) correlated with AGP concentration (r2 = 0.69) but not with albumin concentration, age, or sex. This correlation was verified by adding AGP in varying amounts to control plasma.

Use of procainamide in chronic ambulatory peritoneal dialysis: report of a case

A patient on chronic ambulatory peritoneal dialysis (CAPD) was treated with procainamide for control of ventricular arrhythmias. A procainamide half-life of 11.5 hours was observed, with a dialysis clearance of 6.5 mL/min. The N-acetylprocainamide (NAPA) dialysis clearance was 5.3 mL/min. The CAPD clearance of procainamide and its active metabolite, NAPA, is much lower than that reported for hemodialysis. Procainamide therapy should be initiated with reduced dosages in patients with renal failure.