Biomedical subjects

J C Fleishaker

Publications and source records attributed to J C Fleishaker.

At least 55 records · Page 3Linked to original sources

PubMed1994

The effect of phenytoin on the pharmacokinetics of tirilazad mesylate in healthy male volunteers.

The pharmacokinetic interaction between phenytoin and tirilazad was studied in 12 healthy men who received 200 mg phenytoin orally every 8 hours for 11 doses and 100 mg for the remaining 5 doses in one period of a two-way crossover study. In both periods, 1.5 mg/kg tirilazad mesylate was administered (as 10-minute intravenous infusions) every 6 hours for 21 doses (5 days). Plasma tirilazad mesylate and U-89678 (an active metabolite) were quantified by HPLC. After dose 21, area under the plasma concentration-time curve [AUC(0-6)] for tirilazad mesylate was significantly lower (p = 0.0061) after phenytoin treatment (3029 +/- 982 ng.hr/ml) than after tirilazad mesylate alone (4647 +/- 1562 ng.hr/ml). AUC(0-6) for U-89,678 after dose 21 was reduced from 1485 +/- 1173 ng.hr/ml after tirilazad mesylate alone to 195 +/- 223 ng.hr/ml after phenytoin coadministration. U-89678 normally accumulates during multiple dosing, but mean U-89678 trough concentrations decreased after 24 hours during tirilazad and phenytoin coadministration. No clinically significant interactions of tirilazad mesylate and phenytoin for medical events, vital signs, or laboratory parameters were identified. These results suggest that phenytoin rapidly induces tirilazad mesylate metabolism; it may also induce the metabolism of U-89678 or shunt tirilazad mesylate metabolism through other pathways.

Adolescent↗

PubMed1994

Effect of age and gender on tirilazad pharmacokinetics in humans.

Tirilazad mesylate pharmacokinetics were assessed in 12 young and 12 elderly volunteers (six men and six women per age group). Subjects received single 10-minute intravenous infusions of 1.5 mg/kg and 3.0 mg/kg tirilazad mesylate. Plasma tirilazad mesylate concentrations were determined by HPLC. There were no significant dose effects on clearance, but half-life increased with dose because of assay insensitivity at the lower dose. Mean half-lives were 16.3 +/- 15.5 and 21.4 +/- 12.6 hours for young and elderly subjects, respectively, at the 3.0 mg/kg dose. At the same dose, mean tirilazad mesylate systemic clearance was 0.630 +/- 0.254 and 0.428 +/- 0.090 L/hr/kg, respectively. The decreased clearance in elderly volunteers was primarily attributable to a lower clearance in elderly women relative to young women. The small effect of age on tirilazad clearance is likely to have minimum clinical impact. Tirilazad clearance was approximately 40% higher in young women than in young men. The clinical importance of this observation is unknown.

Adult↗

PubMed1994

Multiple-dose tolerability and pharmacokinetics of tirilazad mesylate at doses of up to 10 mg/kg/day administered over 5-10 days in healthy volunteers.

Multiple dose pharmacokinetics and tolerability of tirilazad mesylate were assessed at the maximum dosage and duration expected for tirilazad mesylate therapy of subarachnoid hemorrhage and head injury. Healthy male subjects (47) received either 1 mg/kg/day, 3 mg/kg/day, 6 mg/kg/day, or 10 mg/kg/day tirilazad mesylate, given as 10 minute i.v. infusions every 6 hours for 21 (at the highest dose) or 41 doses. Plasma tirilazad mesylate and U-89678, an active metabolite, were quantified by HPLC. Thirty-nine subjects completed the study. Tirilazad mesylate was generally well tolerated; injection site irritation was the primary adverse effect. Sporadic, dose unrelated elevations in liver enzymes were observed. All medical events were reversible. No clinically significant effects on vital signs, cardiac telemetry, or other laboratory values were seen. Both tirilazad and U-89678 accumulated on multiple dosing, and steady-state plasma levels were approximated by day 11 of dosing. U-89678 average steady-state concentrations approached 58% of those of the parent compound in the 6.0 mg/kg/day dose group. Following the last dose, mean half-lives for tirilazad ranged from 61.2-123 hours; mean U-89678 half-lives ranged from 60.5-111 hours. Tirilazad mesylate pharmacokinetics exhibited slight nonlinearity, AUC0-6 values for the 6 mg/kg/day were 33% higher than those predicted based on data from the 1.0 mg/kg dose group. Neither the long half-lives of U-89678 and tirilazad nor slight nonlinearity of tirilazad pharmacokinetics are likely to have significant clinical impact during short-term treatment of acute neurological injury.

Adult↗

PubMed1994

Relationship between concentrations of adinazolam and its primary metabolite in plasma and therapeutic/untoward effects in the treatment of panic disorder.

Adinazolam mesylate, a triazolobenzodiazepine with antidepressant and anxiolytic activity, has been shown in several studies to treat panic disorder effectively. This report presents the results of analysis of concentrations in plasma of adinazolam and its primary metabolite, N-desmethyladinazolam (NDMAD), determined as a part of a flexible-dose, double-blind study of the efficacy of adinazolam mesylate sustained release tablets in the treatment of panic disorder with agoraphobia. Dosages administered in the study were titrated from 30 mg/day up to a maximum of 120 mg/day. Concentrations in plasma were determined by high-performance liquid chromatography at clinical evaluations at the end of treatment weeks 1, 2, and 4. The concentrations of both compounds were proportional to the administered dose. An inverted U-shaped concentration-response curve was apparent, where response was based on a priori definitions contained in the study protocol. However, this was probably a result of the flexible-dose study design used. By use of the post hoc definitions of response, as measured by the Clinician's Global Improvement Scale and the total panic attack frequency, logistic regression analysis resulted in more adequate predictions of actual response frequencies. Results indicate that NDMAD contributes to the therapeutic effects of adinazolam mesylate sustained release tablets in the treatment of panic disorder. The exact contributions of adinazolam and NDMAD to response in panic disorder could not be determined, because of the correlation between adinazolam and NDMAD concentrations on multiple dosing.(ABSTRACT TRUNCATED AT 250 WORDS)

Agoraphobia↗

PubMed1993

Evaluation of the pharmacokinetics and tolerability of tirilazad mesylate, a 21-aminosteroid free radical scavenger: I. Single-dose administration.

The single-dose tolerability and pharmacokinetics of tirilazad mesylate, a 21-aminosteroid free radical scavenger, were assessed in 47 healthy male subjects. Subjects were randomized to receive citrate vehicle (n = 12) or 0.25 mg/kg (n = 9), 0.5 mg/kg (n = 9), 1.0 mg/kg (n = 8), or 2.0 mg/kg (n = 9) tirilazad mesylate by 0.5-hour intravenous infusion. Injection site pain was observed with approximately equal frequency in both vehicle and tirilazad mesylate treatment groups. No statistically significant effects of tirilazad mesylate on blood pressure, heart rate, electrocardiograms, liver enzymes, or renal function were apparent. Tirilazad mesylate did not significantly affect measures of glucocorticoid activity (blood glucose, adrenocorticotropic hormone, cortisol, eosinophil, or lymphocyte levels). Maximal plasma concentrations of tirilazad mesylate increased linearly with dose. Limited assay sensitivity at the lower two doses prevented determination of the dose proportionality of tirilazad area under the curve. The apparent elimination half-life at the higher doses was 3.7 hours. Clearance of tirilazad mesylate approached liver blood flow. Results indicate that intravenous infusions at these doses are well tolerated and devoid of glucocorticoid effects. Tirilazad mesylate appears to be efficiently cleared by the liver, and its pharmacokinetics are apparently linear over the dosage range studied.

Adrenocorticotropic Hormone↗

PubMed1993

Evaluation of the pharmacokinetics and tolerability of tirilazad mesylate, a 21-aminosteroid free radical scavenger: II. Multiple-dose administration.

The multiple dose tolerability and pharmacokinetics of tirilazad mesylate, a 21-aminosteroid free radical scavenger, were assessed in 50 healthy male volunteers. Volunteers were randomized to receive intravenous normal saline placebo (n = 10), citrate vehicle placebo (n = 10), or 0.5 mg/kg/day (n = 6), 1.0 mg/kg/day (n = 6), 2.0 mg/kg/day (n = 6), 4.0 mg/kg/day (n = 6), or 6.0 mg/kg/day (n = 6) tirilazad mesylate in divided doses every 6 hours for 5 days, for a total of 21 doses. Drug was infused over 10 or 30 minutes. All tirilazad mesylate treatment groups and the citrate vehicle group had significantly more frequent and more intense pain at the injection site than did the saline group, but the pain intensity did not require interruption of dosing. Three episodes of clinical thrombophlebitis were observed. No statistically significant effects of tirilazad mesylate on blood pressure, heart rate, electrocardiograms, or renal function were apparent. Moderate and transient increases in serum alanine transaminase were observed in several subjects. In the 6.0 mg/kg/day group, 50% of the subjects exhibited increased alanine transaminase. Tirilazad mesylate did not significantly affect measures of glucocorticoid activity (blood glucose, adrenocorticotropic hormone, cortisol, eosinophil, or lymphocyte levels). Tirilazad mesylate pharmacokinetics were linear over the dosage range studied. Steady state appeared to be achieved by the fifth day of dosing. After the last dose, a mean terminal half-life of 35 hours was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Psychomotor and memory effects of two adinazolam formulations assessed by a computerized neuropsychological test battery.

The memory effects of adinazolam were assessed using the computerized neuropsychological test battery (CNTB). In a single-blind crossover study, 12 volunteers received 2 x 20 mg adinazolam mesylate immediate-release (CT) tablets, 2 x 30 mg sustained-release (SR) tablets, and placebo. Plasma adinazolam and N-desmethyladinozolam (NDMAD) were determined by high-pressure liquid chromatography. Choice reaction time and word-list-learning/delayed-recall CNTB modules were administered at 0, 1, 3 and 6 hours after dosing. Adinazolam and NDMAD maximum peak plasma concentration were lower after SR tablets. Immediate-release tablets significantly prolonged reaction time compared with placebo and SR tablets; reaction time after SR tablets did not differ from placebo. Differences between SR and CT tablets in memory were significant only at 1 hour, but memory scores tended to be higher after SR tablet administration than after the CT tablet. At all times, memory scores were significantly lower than placebo for active treatments. Results suggest that memory is more impaired at lower NDMAD concentrations than is psychomotor function.

Anti-Anxiety Agents↗

PubMed1993

Downregulation of serotonin receptor subtypes by nortriptyline and adinazolam in major depressive disorder: neuroendocrine and platelet markers.

Neuroendocrine and platelet markers of serotonin (5-hydroxytryptamine, 5-HT) receptor functioning are useful tools for studying the downregulation of 5-HT receptors, a leading hypothesis for the mechanism of action of antidepressant drugs. The 5-HT releaser fenfluramine raises body temperature as well as plasma concentrations of ACTH, cortisol, and prolactin. Pretreatment with the 5-HT1 antagonist pindolol did not block the hyperthermic response to fenfluramine, mediating its actions via non-5-HT1 receptor subtypes (presumably 5-HT2/1C). We observed blunted hyperthermic responses to fenfluramine in unmedicated patients with major depressive disorder. We also observed that the neuroendocrine responses to fenfluramine were decreased by chronic treatment with the tricyclic antidepressant nortriptyline but not by chronic treatment with tricyclic antidepressant nortriptyline but not by chronic treatment with adinazolam, a triazolobenzodiazepine with purported antidepressant activity. IC50 values for ketanserin inhibition of 5-HT-induced platelet shape change response, a marker of 5-HT2/1c receptors, were elevated after nortriptyline treatment in depressed patients, and this increase could be accounted for by those subjects who responded well to antidepressant treatment. Adinazolam treatment did not alter the platelet shape change response. Our data suggest that downregulation of 5-HT2/1c receptors may be linked to the clinical response of depressed patients treated with nortriptyline.

Anti-Anxiety Agents↗

PubMed1992

Clinical pharmacology of adinazolam and N-desmethyladinazolam mesylate following single intravenous infusions of each compound in health volunteers.

The tolerability, pharmacokinetics and pharmacodynamics of adinazolam and N-desmethyladinazolam (NDMAD) were assessed following intravenous infusions of 5, 10, 15, and 20 mg adinazolam mesylate, 10, 20, 30 and 40 mg NDMAD mesylate, and placebo. Six subjects per dose level received treatments in a double-blind crossover design. No clinically significant changes were seen in blood pressure, pulse, respiration, or clinical laboratory parameters. Untoward effects typical of benzodiazepines were observed almost exclusively after NDMAD administration. Adinazolam and NDMAD pharmacokinetics were dose-independent. NDMAD clearance was 50% of the value for adinazolam. Adinazolam and NDMAD administrations increased uric acid clearance and decreased plasma uric acid. Adinazolam administration had no significant effect on psychomotor performance. NDMAD administration produced dose related decreases in performance; 286 ng/ml NDMAD produced a 50% decrease in DSST. These results confirm that adinazolam and NDMAD both produce uricosuria and definitively show that adinazolam is devoid of benzodiazepine-like effects at therapeutic concentrations; NDMAD mediates these effects. Uricosuric activity is present for both compounds, but the relative potencies are still unknown.

Adolescent↗

PubMed1992

Pharmacokinetic and pharmacodynamic comparison of immediate-release and sustained-release adinazolam mesylate tablets after single- and multiple-dose administration.

The effect of adinazolam release rate on psychomotor performance and sedation was assessed by administering 40 mg adinazolam mesylate immediate-release (CT) tablets, 60 mg sustained-release (SR) tablets, and placebo in a double-blind crossover study in 15 healthy male subjects. A separate panel of 16 subjects received the above single doses and multiple-dose regimens of 40 mg CT tablets every 8 hr and 60 mg SR tablets every 12 hr according to a crossover design. Psychomotor performance was assessed by digit symbol substitution test, card sorting tasks, and sedation ratings. Following single-dose administration, dose-corrected adinazolam and N-desmethyladinazolam (NDMAD) AUC values were equivalent for SR and CT tablets. Peak adinazolam and NDMAD levels were lower and occurred later for the SR tablets. Decrements in card sorting were 50 and 3% at 1 hr and 17 and 20% at 6 hr for the CT and SR tablets, respectively. Maximal sedation scores were lower for the SR tablets compared to the CT. Dose-corrected AUC was comparable between single and multiple doses for both adinazolam and NDMAD; no differences were observed in 24-hr AUC at steady-state between CT and SR tablets. Fluctuation ratios were reduced for both adinazolam and NDMAD following SR tablets. Psychomotor and sedative effects were attenuated upon multiple dosing. Thus, the reduction in peak plasma NDMAD following SR tablet administration results in a lesser sedation and psychomotor impairment on acute administration, and tolerance to these effects occurs on multiple dosing.

Adult↗

PubMed1992

Pharmacokinetics and pharmacodynamics of adinazolam and N-desmethyladinazolam after oral and intravenous dosing in healthy young and elderly volunteers.

The pharmacokinetics and pharmacodynamics of adinazolam and N-desmethyladinazolam were studied in 18 young subjects, from 21 to 36 years of age, and 18 elderly subjects, ranging in age from 65 to 76 years. Nine men and 9 women per age group were studied in a randomized three-way crossover design. Single doses of one 30-mg adinazolam mesylate sustained release tablet, one 30-mg immediate release tablet, and 15 mg of intravenous adinazolam mesylate were administered. Plasma adinazolam and N-desmethyladinazolam were determined by high-performance liquid chromatography, and psychomotor performance tests, including digit-symbol substitution and two card-sorting tasks, were performed. An effect index, defined as the maximal performance decrement divided by N-desmethyladinazolam maximum plasma concentration was calculated as a measure of sensitivity to these effects. Adinazolam oral and systemic clearances were reduced approximately 30% and 25%, respectively, in elderly volunteers. Adinazolam half-life was prolonged approximately 40% in the elderly after oral dosing. N-Desmethyladinazolam plasma concentrations and half-life were increased approximately 40% in elderly volunteers. Psychomotor performance decrements were observed following all treatments; decrements were lowest following sustained release tablets and intravenous adinazolam. Maximal performance decrements in elderly subjects were approximately twice those observed in young subjects. No significant influence of age on the effect index for digit-symbol substitution was evident. Effect indices for card-sorting tests were significantly higher in the elderly. Lower clearances of adinazolam and N-desmethyladinazolam are observed in elderly volunteers, and increased N-desmethyladinazolam levels contribute to increased psychomotor performance decrements in elderly subjects. Results also suggest that elderly subjects may be more sensitive to certain cognitive effects of N-desmethyladinazolam.

Administration, Oral↗

PubMed1992

Ranitidine does not alter adinazolam pharmacokinetics or pharmacodynamics.

Adinazolam is a triazolobenzodiazepine with anxiolytic and antidepressant activity. Adinazolam is metabolized extensively; the major metabolite, N-desmethyladinazolam (NDMAD), possesses significant pharmacologic activity. NDMAD is eliminated predominantly by renal excretion. Ranitidine, a histamine H2-receptor antagonist, is also excreted renally and may compete with NDMAD for renal secretion. The purpose of this study was to examine the effect of ranitidine on the pharmacokinetics and pharmacodynamics of adinazolam and NDMAD. In a randomized, cross-over study, 12 healthy male volunteers received 300 mg of ranitidine orally followed by 30 mg of adinazolam 1 hour later (treatment A), or adinazolam alone (treatment B). Pharmacodynamic alterations were assessed using card sorting, digit-symbol substitution, and short-term memory tests. Venous blood samples were obtained over 24 hours for analysis of adinazolam and NDMAD by high-performance liquid chromatography. Urine samples also were collected and analyzed for NDMAD. No significant difference in adinazolam oral clearance (1,149 vs. 1,135 ml/hr/kg) was noted between treatments (A vs. B, respectively). Furthermore, the renal clearance of NDMAD (196 vs. 198 ml/min) and the cumulative urinary excretion of NDMAD (% dose; 61.2 vs. 62.3) were not significantly different. Repeated-measures analysis of variance indicated no significant differences in psychomotor performance or short-term memory between treatments. Results suggest that ranitidine has no effect on adinazolam disposition, NDMAD renal clearance, or the central nervous system effects mediated by the drug.

Adult↗

PubMed1991

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)

Administration, Oral↗

PubMed1991

Evaluation of a potential interaction between erythromycin and glyburide in diabetic volunteers.

The effects of erythromycin on the pharmacokinetics and pharmacodynamics of glyburide were evaluated in 12 patients with non-insulin-dependent diabetes mellitus (fasting blood glucose levels 140-280 mg/dL), who received 4 days of treatment with erythromycin base (333 mg administered orally every 8 hr) and a control treatment in a randomized crossover design; 5 mg glyburide was administered on day 4 of each study period. Serum glyburide concentrations were determined by high-performance liquid chromatography. Peak serum glyburide concentrations were increased by 18%, and mean time to peak glyburide concentrations (Tmax) decreased from 4.9 to 3.0 hours during erythromycin treatment; only the difference in Tmax was statistically significant. No significant effects on glyburide clearance were observed. No significant differences in glucose clearance after carbohydrate loads were observed between erythromycin + glyburide and glyburide treatments. These data show that oral erythromycin base treatment does not affect glyburide metabolism but does affect the rate of glyburide absorption. This effect may be mediated by the stimulation of gastric motility by erythromycin. The clinical significance of the effects of erythromycin on glyburide kinetics appears to be minimal, based on the determinations of serum glucose concentrations.

Adult↗

PubMed1991

N-desmethyladinazolam pharmacokinetics and behavioral effects following administration of 10-50 mg oral doses in healthy volunteers.

Results of previous studies suggest that N-desmethyladinazolam, the major metabolite of adinazolam in man, contributes substantially to psychomotor effects and sedation observed following adinazolam administration. Therefore, the pharmacokinetics and pharmacodynamics of N-desmethyladinazolam were explored following administration of single oral doses of placebo and solutions containing 10, 30, and 50 mg N-desmethyladinazolam mesylate in a double-blind, randomized, four-way crossover design to 15 healthy male volunteers. Plasma concentrations of N-desmethyladinazolam were determined by HPLC. Psychomotor performance tests (digit symbol substitution and card sorting by fours and suits), memory tests and sedation scoring were also performed following drug administration. N-Desmethyladinazolam pharmacokinetics were dose independent over this range. Dose-related performance effects were observed at 1, 2, and 6 h after dosing. Memory was likewise affected at 2 h. Psychomotor performance decrements correlated with log N-desmethyladinazolam plasma concentrations. Analysis of the relationship between percentage decrements in digit-symbol substitution and plasma N-desmethyladinazolam using the Hill equation revealed a EC50 of 325 ng/ml. These results establish the relationship between N-desmethyladinazolam plasma concentrations and performance effects; these data will be helpful in assessing the contribution of N-desmethyladinazolam to clinical effects observed after adinazolam administration.

Adult↗

PubMed1991

Pharmacokinetic pharmacodynamic evaluation of the combined administration of alprazolam and fluoxetine.

The pharmacokinetic and pharmacodynamic effects of concomitant administration of alprazolam and fluoxetine were studied in this double-blind parallel study in 80 healthy, male volunteers. Subjects were randomly assigned to one of four treatment groups. Drug treatments consisted of 4-day regimens of 1 mg alprazolam four times daily, 60 mg fluoxetine every morning, 1 mg alprazolam four times daily and 60 mg fluoxetine every morning, and placebo four times daily. Psychomotor performance, mood status, and degree of sedation were evaluated at designated times. Combined administration of alprazolam and fluoxetine resulted in an approximate 30% increase in plasma alprazolam concentrations relative to plasma concentrations following the administration of alprazolam alone. There were no significant differences in fluoxetine or norfluoxetine plasma concentrations between the alprazolam/fluoxetine and fluoxetine treatments. Psychomotor decrements increased when fluoxetine was administered with alprazolam relative to alprazolam administration alone. Psychomotor performance of the fluoxetine treatment group was not significantly different from that of the placebo group. No significant changes were observed in mood status, and sedation was minimal in all treatment groups. As when any two psychoactive drugs are administered together, increased patient monitoring and patient education is recommended when alprazolam and fluoxetine are prescribed concurrently.

Adult↗

PubMed1991

In vitro and in vivo evaluation of whole and half tablets of sustained-release adinazolam mesylate.

The mechanism of release from sustained-release adinazolam mesylate tablets was assessed by the Higuchi equation and by analysis of drug release profiles through 60% released using the Peppas equation. Computed values of the diffusional exponent, n, ranged from 0.59 to 0.66. Values of n in this range are consistent with a mixed mechanism of release, with diffusion of drug through the hydrated polymer matrix and relaxation of this matrix being the principal processes controlling release. The rate of in vitro drug release was increased for half tablets relative to whole tablets and is attributed to an increase in the surface to volume ratio of half tablets of about 16%. This increase in surface-to-volume ratio of half tablets was reflected by an increase in the constant, k, from the Peppas equation of 20-23% and by an increase in the slope of Higuchi plots of 12-18% for four lots of tablets. In vivo/in vitro relationships from two bioavailability studies were thoroughly evaluated. Using either a linear or a quadratic relationship, an in vivo/in vitro correlation exists for sustained-release adinazolam mesylate tablets.

Adolescent↗

PubMed1991

Extent and variability of the first-pass elimination of adinazolam mesylate in healthy male volunteers.

The pharmacokinetics of adinazolam and N-desmethyladinazolam (NDMAD) were studied in 14 healthy male volunteers who received 15 mg adinazolam mesylate orally as a solution and 5 mg adinazolam mesylate intravenously in a crossover design. Two weeks prior to the crossover study, each subject received 5 mg/kg indocyanine green (ICG) as an intravenous bolus injection to estimate liver blood flow. The absolute bioavailability (F), calculated as the dose-corrected ratio of oral to iv adinazolam area under the curve (AUC) values, was found to be 39%. NDMAD AUC values were similar following oral and iv administration, and adinazolam mean absorption time was approximately 0.77 hr. Thus, adinazolam is completely and rapidly absorbed after oral administration in man; the incomplete bioavailability is due to first-pass metabolism. Mean liver blood flow, adinazolam systemic clearance, blood/plasma ratio, and extraction ratio were 1189 ml/min, 498 ml/min, 0.70, and 0.57, respectively. The extraction ratio agrees with that calculated as 1-F (0.62), suggesting that the liver is primarily responsible for first-pass metabolism of adinazolam. The unbound fraction of adinazolam in plasma was 0.31 (range, 0.25-0.36); adinazolam free intrinsic clearance (a reflection of metabolic capacity) was 4285 ml/min (range, 2168-6312 ml/min). These results suggest that the majority of the variability in adinazolam plasma concentrations following oral administration is due to the variability in the metabolic capacity of the liver for adinazolam, rather than variability in plasma protein binding.

Adult↗