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Dinis-Oliveira RJ. Metabolic profile of oxazepam and related benzodiazepines: clinical and forensic aspects. Drug Metab Rev 2017; 49:451-463. [PMID: 28903606 DOI: 10.1080/03602532.2017.1377223] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Anxiolytic drugs, namely benzodiazepines, are the most commonly used psychoactive substances since anxiety disorders are prevalent mental disorders particularly in the Western world. Oxazepam is a short-acting benzodiazepine and one of the most frequently prescribed anxiolytic drugs. It is also the active metabolite of a wide range of other benzodiazepines, such as diazepam, ketazolam, temazepam, chlordiazepoxide, demoxazepam, halazepam, medazepam, prazepam, pinazepam, and chlorazepate. Therefore, relevant clinical and forensic outocomes may arise, namely those related to interference in driving performance. It is clinically available as a racemic formulation, with S-enantiomer being more active than R-enantiomer. In humans, it is mainly polimorphically metabolized by glucuronide conjugation at the 3-carbon hydroxyl group, yielding stable diastereomeric glucuronides (R- and S-oxazepam glucuronide). Relevant metabolic and stereoselective interspecies differences have been reported. In this work, the pharmacokinetics of oxazepam with particular focus on metabolic pathways is fully reviewed. Moreover, the metabolic profile of other prescribed benzodiazepines that produce oxazepam as a metabolite is also discussed. It is aimed that knowing the metabolism of oxazepam and related benzodiazepines may lead to the development of new analytical strategies for its early detection and help in further toxicological and clinical interpretations.
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Affiliation(s)
- Ricardo Jorge Dinis-Oliveira
- a IINFACTS - Institute of Research and Advanced Training in Health Sciences and Technologies, Department of Sciences , University Institute of Health Sciences (IUCS), CESPU, CRL , Gandra , Portugal.,b UCIBIO-REQUIMTE, Laboratory of Toxicology, Department of Biological Sciences, Faculty of Pharmacy , University of Porto , Porto , Portugal.,c Department of Public Health and Forensic Sciences, and Medical Education, Faculty of Medicine , University of Porto , Porto , Portugal
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Dorne JL, Walton K, Renwick AG. Human variability in glucuronidation in relation to uncertainty factors for risk assessment. Food Chem Toxicol 2001; 39:1153-73. [PMID: 11696390 DOI: 10.1016/s0278-6915(01)00087-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The appropriateness of the default uncertainty factor for human variability in kinetics has been investigated for glucuronidation using an extensive database of substrates metabolised primarily by this pathway. Inter-individual variability was quantified for 15 compounds from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating to chronic exposure (metabolic and total clearances, area under the plasma concentration time-curve (AUC)) and acute exposure (C(max)). Low inter-individual variability (about 30-35%) was found for all parameters (clearance corrected or not corrected for body weight, metabolic clearance, oral AUC and C(max)) after either iv or oral administration to healthy adults. The overall variability of 31% for glucuronidation in healthy adults supported the validity of the default kinetic uncertainty factor of 3.16 for this group, because it would cover more than 99% of individuals. Comparisons between potentially sensitive subgroups and healthy adults using differences in means and variability indicated that neonates showed the greatest impairment of glucuronidation, and that the 3.16 kinetic default factor applied to the mean data for adults would be inadequate for this subpopulation. The in vivo data have been used to derive pathway-related default factors for compounds eliminated largely via glucuronidation.
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Affiliation(s)
- J L Dorne
- Clinical Pharmacology Group, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, SO16 7PX, Southampton, UK
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Greenblatt DJ, von Moltke LL, Ehrenberg BL, Harmatz JS, Corbett KE, Wallace DW, Shader RI. Kinetics and dynamics of lorazepam during and after continuous intravenous infusion. Crit Care Med 2000; 28:2750-7. [PMID: 10966246 DOI: 10.1097/00003246-200008000-00011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To evaluate the kinetics and dynamics of lorazepam during administration as a bolus plus an infusion, using electroencephalography as a pharmacodynamic end point. METHODS Nine volunteers received a 2-mg bolus loading dose of lorazepam, coincident with the start of a 2 microg/kg/hr zero-order infusion. The infusion was stopped after 4 hrs. Plasma lorazepam concentrations and electroencephalographic activity in the 13- to 30-Hz range were monitored for 24 hrs. RESULTS The bolus-plus-infusion scheme rapidly produced plasma lorazepam concentrations that were close to those predicted to be achieved at true steady state. Mean kinetic values for lorazepam were as follows: volume of distribution, 126 L; elimination half-life, 13.8 hrs; and clearance, 109 mL/min. Electroencephalographic effects were maximal 0.5 hr after the loading dose, were maintained essentially constant during infusion, and then declined in parallel with plasma concentrations after the infusion was terminated. There was no evidence of tolerance. Plots of pharmacodynamic electroencephalographic effect vs. plasma lorazepam concentration demonstrated counterclockwise hysteresis, consistent with an effect-site equilibration delay. This was incorporated into a kinetic-dynamic model in which hypothetical effect-site concentration was related to pharmacodynamic electroencephalographic effect via the sigmoid Emax model. The analysis yielded the following mean estimates: maximum electroencephalographic effect, 12.7% over baseline; 50% effective concentration, 13.1 ng/mL; and effect-site equilibration half-life, 8.8 mins. CONCLUSION Despite the delay in effect onset, continuous infusion of lorazepam, preceded by a bolus loading dose, produces a relatively constant sedative effect on the central nervous system, which can be utilized in the context of critical care medicine.
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Affiliation(s)
- D J Greenblatt
- Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA.
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Fleishaker JC, Phillips JP, Lau HS. Effect of food on the bioavailability of adinazolam from a sustained release formulation: effect of meal timing and lack of dose dumping. Biopharm Drug Dispos 1990; 11:715-27. [PMID: 2271747 DOI: 10.1002/bdd.2510110807] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Food effects on adinazolam absorption from sustained release (SR) adinazolam mesylate tablets were assessed in 28 healthy male volunteers. Subjects received 15 mg SR tablets, 15 mg immediate release tablets, 15 mg oral solution, administered after an overnight fast, and 15 mg SR tablets after a high fat breakfast. Treatments were administered in a crossover design. Plasma adinazolam and N-desmethyladinazolam (NDMAD) concentrations were determined by HPLC. Adinazolam and NDMAD AUC values were unaffected by food. Cmax for SR tablets was increased 33 per cent and 18 per cent for adinazolam and NDMAD, respectively, when administered postprandially. Tmax occurred later in the fed state; no dose dumping was observed. Meal timing effects on adinazolam absorption from SR tablets were assessed in 24 healthy subjects, who received 30 mg SR tablets 1 h before, 0.5 h after, 2 h after a high fat meal, and in the fasted state. Postprandial administration had no effect on AUC, but resulted later and higher adinazolam and NDMAD Cmax. Differences in these values were less than 11 per cent. Administration of SR tablets before meals yielded Cmax and Tmax values which were similar to the fasted state. Results suggest that meal timing does not substantially affect adinazolam absorption from the SR tablet.
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Affiliation(s)
- J C Fleishaker
- Clinical Pharmacokinetics Unit, Upjohn Company, Kalamazoo, MI 49001
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Eller MG, Della-Coletta AA. Absence of effect of food on alprazolam absorption from sustained release tablets. Biopharm Drug Dispos 1990; 11:31-7. [PMID: 2322635 DOI: 10.1002/bdd.2510110104] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
This study examined the effect of food on alprazolam absorption from a mixed polymeric matrix sustained release (SR) tablet in 21 healthy adults. Each subject received each of three treatments according to a crossover design: 1 mg alprazolam SR tablet while fasting; 1 mg alprazolam SR tablet immediately after a standardized breakfast; 1 mg alprazolam conventional tablet while fasting. The breakfast contained approximately 33 g protein, 55 g fat, and 58 g carbohydrate (850 calories). Serial blood samples were obtained and plasma alprazolam levels determined by HPLC. Results indicate that the SR tablet was minimally affected by food. Relative bioavailabilities of the SR tablet while fasting and with food were 100 per cent and 97 per cent, respectively. Although statistically significant, differences in mean Cmax values between SR tablets administered with and without food were small (12 per cent increase with food). Rates of absorption as measured by mean tmax values were also nearly the same: 7.2 h while fasting and 7.0 h with food. Absorption was relatively uniform with the SR tablets. Coefficients of variation for Cmax, tmax, and AUC were somewhat smaller with the SR tablet than with the conventional tablet.
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Affiliation(s)
- M G Eller
- Clinical Pharmacokinetics Unit, Upjohn Company, Kalamazoo, MI 49001
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Bareggi SR, Pirola R, Truci G, Leva S, Smirne S. Effect of after-dinner administration on the pharmacokinetics of oral flunitrazepam and loprazolam. J Clin Pharmacol 1988; 28:371-5. [PMID: 3392235 DOI: 10.1002/j.1552-4604.1988.tb03161.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The pharmacokinetics of two benzodiazepine hypnotics, flunitrazepam and loprazolam, was determined on two occasions in two groups of eight healthy volunteers. Single 2-mg oral doses of either drug were given in the fasting state at morning on one occasion and after a standard dinner at night on another. Compared with administration of drugs in the fasting state, administration of the drugs after dinner decreased peak plasma concentrations, delayed the time to reach maximum concentration, and prolonged the absorption half-life. The extent of absorption was reduced for flunitrazepam but not for loprazolam. The elimination half-life of both flunitrazepam and loprazolam was not changed in the two conditions. These changes may be of clinical significance because they can delay and reduce the effects of the drugs.
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Affiliation(s)
- S R Bareggi
- Department of Pharmacology, School of Medicine, Università degli Studi, Milan, Italy
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Hamaguchi T, Shinkuma D, Yamanaka Y, Mizuno N. Bioavailability of mefenamic acid: influence of food and water intake. J Pharm Sci 1986; 75:891-3. [PMID: 3783459 DOI: 10.1002/jps.2600750914] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The influence of food and water intake on mefenamic acid (N-2,3-xylylanthranilic acid) bioavailability from commercial capsules of high bioavailability was studied in four healthy male volunteers. The drug was administered as a single oral dose of 250 mg, under fasting or nonfasting conditions, and a 4 X 4 Latin-square design was used. Eight blood samples were collected over a 24-h period following drug administration, and the drug plasma concentrations were determined by HPLC. The bioavailability of mefenamic acid from capsules was markedly influenced in the fasting subjects by the water but not by the food intake. A good correlation was found between the bioavailability and amount of water ingested with the drug in the fasting subjects. The area under the plasma concentration-time curve (AUC0-infinity) of mefenamic acid was highest when the capsule was taken with 50 mL of water or immediately after a meal. Increasing the amount of water from 50 to 500 mL in the fasting subjects caused a significant reduction in AUC0-infinity.
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Locniskar A, Greenblatt DJ, Zinny MA, Harmatz JS, Shader RI. Absolute bioavailability and effect of food and antacid on diazepam absorption from a slow-release preparation. J Clin Pharmacol 1984; 24:255-63. [PMID: 6747022 DOI: 10.1002/j.1552-4604.1984.tb02782.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A series of healthy volunteers received a single 7.5-mg intravenous dose of diazepam on one occasion and a single 15-mg oral dose of slow-release diazepam (DZ-SR) on another occasion. Diazepam concentrations were measured by gas chromatography in multiple plasma samples drawn during seven days after each dose. Absorption of diazepam from DZ-SR was slow, with mean +/- S.E. peak concentrations attained at 3.8 +/- 0.5 hours after dosage. Absolute bioavailability of DZ-SR averaged 0.98 +/- 0.06. In two other studies, diazepam absorption from DZ-SR was evaluated when coadministered with a standard breakfast or with an antacid preparation (Maalox). Neither food nor antacid altered the rate of diazepam absorption and did not impair the completeness of absorption. Higher peak total plasma diazepam concentrations occurred in the postprandial as opposed to the fasting state, but this was an artifact of reduced protein binding (increased free fraction) due to fasting. Thus, diazepam absorption from DZ-SR is slow and essentially complete.
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Cenraud B, Guyot M, Levy RH, Brachet-Liermain A, Morselli PL, Moreland TA, Loiseau P. No effect of food intake on clobazam absorption. Br J Clin Pharmacol 1983; 16:728-30. [PMID: 6661360 PMCID: PMC1428358 DOI: 10.1111/j.1365-2125.1983.tb02251.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The kinetics of clobazam taken 3 h before, during, and 3 h after a standard hospital meal were studied in six healthy volunteers. Peak plasma levels were significantly lower when the drug was taken with or after meals suggesting that the rate of absorption was reduced by food. The mean area under the concentration vs time curve was not affected by the time of drug administration indicating that the meal had no effect upon the extent of absorption.
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Divoll M, Greenblatt DJ, Ciraulo DA, Puri SK, Ho I, Shader RI. Clobazam kinetics: intrasubject variability and effect of food on adsorption. J Clin Pharmacol 1982; 22:69-73. [PMID: 7061729 DOI: 10.1002/j.1552-4604.1982.tb05711.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The kinetics of single 20-mg oral doses of clobazam was determined on two occasions in 12 healthy male volunteers. Clobazam was given in the fasting state on one occasion and following a standard breakfast on another. Compared with the fasting state, administration of clobazam with food reduced mean peak plasma concentrations (465 vs. 333 ng/ml, P less than 0.01), and prolonged the time to reach peak concentration (1.7 vs. 2.5 hours after dosage, P less than 0.1). Total area under the curve nor the extent of formation of desmethylclobazam, the major metabolite. Clobazam AUC and elimination half-life each were highly correlated within subjects between the two trials (r = 0.97 and 0.95, respectively). Thus, administration of clobazam with food slows the rate of clobazam absorption but does not alter the completeness of absorption. The rate of drug elimination is highly replicable upon repeated administration clobazam to the same individual.
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Walden RJ, Hernandez R, Witts D, Graham BR, Prichard BN. Effect of food on the absorption of hydralazine in man. Eur J Clin Pharmacol 1981; 20:53-8. [PMID: 7308273 DOI: 10.1007/bf00554667] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Single oral doses of hydralazine (Apresoline) 50 mg were administered on two occasions to eight healthy volunteers when fed and fasting. Blood and saliva samples were taken at intervals after dosing and analysed for drug. Heart rate and blood pressure were measured before and at intervals after dosing, at rest, after tilt and exercise. Plasma hydralazine levels showed wide inter-individual variation. The areas under the plasma concentration-time curve (0-8 h), the height of the peak plasma levels and the time to peak were not significantly different between the fed and fasting state. Salivary hydralazine levels were readily measurable but showed little correlation with plasma levels. The heart rate and pulse pressure were increased after drug both at rest, supine and erect, and after exercise for between 6 and 8 h.
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Melander A, Brante G, Johansson O, Lindberg T, Wåhlin-Boll E. Influence of food on the absorption of phenytoin in man. Eur J Clin Pharmacol 1979; 15:269-74. [PMID: 477711 DOI: 10.1007/bf00618516] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The influence of food intake on the absorption of phenytoin was examined in eight healthy volunteers, by study of single-dose kinetics following ingestion of phenytoin 300 mg either with a standardized breakfast or on an empty stomach. Blood samples were collected at regular intervals from 0 to 48 h, and serum concentrations of unmetabolized phenytoin were determined by gas chromatography. Serum concentrations of the major metabolite of phenytoin, 4-hydroxyphenytoin, were measured by mass fragmentography. Concurrent intake of food and phenytoin appeared to accelerate absorption of the drug from the formulation used, and the peak concentrations were significantly higher (mean increase 40%) in the postprandial than in the preprandial state. As reflected by the AUC (area under the curve), the amount of drug absorbed was increased during postprandial conditions, although the difference only reached borderline significance. It is suggested that phenytoin should always be taken in a defined relation to meals.
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Vree TB, Baars AM, Hekster YA, van der Kleijn E, O'Reilly WJ. Simultaneous determination of diazepam and its metabolies N-desmethyldiazepam, oxydiazepam and oxazepam in plasma and urine of man and dog by means of high-performance liquid chromatography. JOURNAL OF CHROMATOGRAPHY 1979; 162:605-14. [PMID: 43333 DOI: 10.1016/s0378-4347(00)81842-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Melander A, Wåhlin E. Enhancement of dicoumarol bioavailability by concomitant food intake. Eur J Clin Pharmacol 1978; 14:441-4. [PMID: 83942 DOI: 10.1007/bf00716387] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The influence of food intake on the bioavailability of dicoumarol from a non-micronized formulation was examined in ten healthy volunteers, by examination of its single-dose kinetics after ingestion of dicoumarol 250 mg with a standardized breakfast and on an empty stomach. Blood samples were collected at regular intervals from 0 to 72 h, and the serum concentration of unmetabolized dicoumarol was determinded by spectrophotometry. Postprandial AUC (area under the curve) values were significantly (p less than 0.01) greater than the preprandial figures, the mean increase being 85 per cent. The results suggest that dicoumarol should always be taken with food.
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