Relative bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension

Pamela L. Clemens, James C Cloyd, Robert L. Kriel, Rory P Remmel

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Background and objective: Maintenance of effective drug concentrations is essential for adequate treatment of epilepsy. Some antiepileptic drugs can be successfully administered rectally when the oral route of administration is temporarily unavailable. Oxcarbazepine is a newer antiepileptic drug that is rapidly converted to a monohydroxy derivative, the active compound. This study aimed to characterise the bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension using a randomised, crossover design in ten healthy volunteers. Methods: Two subjects received 300mg doses of oxcarbazepine suspension via rectal and oral routes and eight received 450mg doses. A washout period of at least 2 weeks elapsed between doses. The rectal dose was diluted 1:1 with water. Blood samples and urine were collected for 72 hours post-dose. Adverse effects were assessed at each blood collection time-point using a self-administered questionnaire. Plasma was assayed for oxcarbazepine and monohydroxy derivative; urine was assayed for monohydroxy derivative and monohydroxy derivative-glucuronide. Maximum plasma concentration (Cmax) and time to reach Cmax (tmax) were obtained directly from the plasma concentration-time curves. The areas under the concentration-time curve (AUCs) were determined via noncompartmental analysis. Relative bioavailability was calculated and the Cmax and AUCs were compared using Wilcoxon signed-rank tests. Results: Mean relative bioavailability calculated from plasma AUCs was 8.3% (SD 5.5%) for the monohydroxy derivative and 10.8% (SD 7.3%) for oxcarbazepine. Oxcarbazepine and monohydroxy derivative Cmax and AUC values were significantly lower following rectal administration (p < 0.01). The total amount of monohydroxy derivative excreted in the urine following rectal administration was 10 ± 5% of the amount excreted following oral administration. Oral absorption was consistent with previous studies. The most common adverse effects were headache and fatigue with no discernible differences between routes. Conclusions: Monohydroxy derivative bioavailability following rectal administration of oxcarbazepine suspension is significantly lower than following oral administration, most likely because of poor oxcarbazepine water solubility. It is unlikely that adequate monohydroxy derivative concentrations can be achieved with rectal administration of diluted oxcarbazepine suspension.

Original languageEnglish (US)
Pages (from-to)243-250
Number of pages8
JournalClinical Drug Investigation
Volume27
Issue number4
DOIs
StatePublished - Mar 23 2007

Fingerprint

Biological Availability
Suspensions
Rectal Administration
Oral Administration
Urine
Anticonvulsants
oxcarbazepine
Water
Glucuronides
Nonparametric Statistics
Solubility
Cross-Over Studies
Fatigue
Headache
Epilepsy
Healthy Volunteers
Pharmaceutical Preparations

Cite this

Relative bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension. / Clemens, Pamela L.; Cloyd, James C; Kriel, Robert L.; Remmel, Rory P.

In: Clinical Drug Investigation, Vol. 27, No. 4, 23.03.2007, p. 243-250.

Research output: Contribution to journalArticle

@article{8cc9e0d1a2884226a3e8fe67ae2ce5d6,
title = "Relative bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension",
abstract = "Background and objective: Maintenance of effective drug concentrations is essential for adequate treatment of epilepsy. Some antiepileptic drugs can be successfully administered rectally when the oral route of administration is temporarily unavailable. Oxcarbazepine is a newer antiepileptic drug that is rapidly converted to a monohydroxy derivative, the active compound. This study aimed to characterise the bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension using a randomised, crossover design in ten healthy volunteers. Methods: Two subjects received 300mg doses of oxcarbazepine suspension via rectal and oral routes and eight received 450mg doses. A washout period of at least 2 weeks elapsed between doses. The rectal dose was diluted 1:1 with water. Blood samples and urine were collected for 72 hours post-dose. Adverse effects were assessed at each blood collection time-point using a self-administered questionnaire. Plasma was assayed for oxcarbazepine and monohydroxy derivative; urine was assayed for monohydroxy derivative and monohydroxy derivative-glucuronide. Maximum plasma concentration (Cmax) and time to reach Cmax (tmax) were obtained directly from the plasma concentration-time curves. The areas under the concentration-time curve (AUCs) were determined via noncompartmental analysis. Relative bioavailability was calculated and the Cmax and AUCs were compared using Wilcoxon signed-rank tests. Results: Mean relative bioavailability calculated from plasma AUCs was 8.3{\%} (SD 5.5{\%}) for the monohydroxy derivative and 10.8{\%} (SD 7.3{\%}) for oxcarbazepine. Oxcarbazepine and monohydroxy derivative Cmax and AUC values were significantly lower following rectal administration (p < 0.01). The total amount of monohydroxy derivative excreted in the urine following rectal administration was 10 ± 5{\%} of the amount excreted following oral administration. Oral absorption was consistent with previous studies. The most common adverse effects were headache and fatigue with no discernible differences between routes. Conclusions: Monohydroxy derivative bioavailability following rectal administration of oxcarbazepine suspension is significantly lower than following oral administration, most likely because of poor oxcarbazepine water solubility. It is unlikely that adequate monohydroxy derivative concentrations can be achieved with rectal administration of diluted oxcarbazepine suspension.",
author = "Clemens, {Pamela L.} and Cloyd, {James C} and Kriel, {Robert L.} and Remmel, {Rory P}",
year = "2007",
month = "3",
day = "23",
doi = "10.2165/00044011-200727040-00003",
language = "English (US)",
volume = "27",
pages = "243--250",
journal = "Clinical Drug Investigation",
issn = "0114-2402",
publisher = "Adis International Ltd",
number = "4",

}

TY - JOUR

T1 - Relative bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension

AU - Clemens, Pamela L.

AU - Cloyd, James C

AU - Kriel, Robert L.

AU - Remmel, Rory P

PY - 2007/3/23

Y1 - 2007/3/23

N2 - Background and objective: Maintenance of effective drug concentrations is essential for adequate treatment of epilepsy. Some antiepileptic drugs can be successfully administered rectally when the oral route of administration is temporarily unavailable. Oxcarbazepine is a newer antiepileptic drug that is rapidly converted to a monohydroxy derivative, the active compound. This study aimed to characterise the bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension using a randomised, crossover design in ten healthy volunteers. Methods: Two subjects received 300mg doses of oxcarbazepine suspension via rectal and oral routes and eight received 450mg doses. A washout period of at least 2 weeks elapsed between doses. The rectal dose was diluted 1:1 with water. Blood samples and urine were collected for 72 hours post-dose. Adverse effects were assessed at each blood collection time-point using a self-administered questionnaire. Plasma was assayed for oxcarbazepine and monohydroxy derivative; urine was assayed for monohydroxy derivative and monohydroxy derivative-glucuronide. Maximum plasma concentration (Cmax) and time to reach Cmax (tmax) were obtained directly from the plasma concentration-time curves. The areas under the concentration-time curve (AUCs) were determined via noncompartmental analysis. Relative bioavailability was calculated and the Cmax and AUCs were compared using Wilcoxon signed-rank tests. Results: Mean relative bioavailability calculated from plasma AUCs was 8.3% (SD 5.5%) for the monohydroxy derivative and 10.8% (SD 7.3%) for oxcarbazepine. Oxcarbazepine and monohydroxy derivative Cmax and AUC values were significantly lower following rectal administration (p < 0.01). The total amount of monohydroxy derivative excreted in the urine following rectal administration was 10 ± 5% of the amount excreted following oral administration. Oral absorption was consistent with previous studies. The most common adverse effects were headache and fatigue with no discernible differences between routes. Conclusions: Monohydroxy derivative bioavailability following rectal administration of oxcarbazepine suspension is significantly lower than following oral administration, most likely because of poor oxcarbazepine water solubility. It is unlikely that adequate monohydroxy derivative concentrations can be achieved with rectal administration of diluted oxcarbazepine suspension.

AB - Background and objective: Maintenance of effective drug concentrations is essential for adequate treatment of epilepsy. Some antiepileptic drugs can be successfully administered rectally when the oral route of administration is temporarily unavailable. Oxcarbazepine is a newer antiepileptic drug that is rapidly converted to a monohydroxy derivative, the active compound. This study aimed to characterise the bioavailability, metabolism and tolerability of rectally administered oxcarbazepine suspension using a randomised, crossover design in ten healthy volunteers. Methods: Two subjects received 300mg doses of oxcarbazepine suspension via rectal and oral routes and eight received 450mg doses. A washout period of at least 2 weeks elapsed between doses. The rectal dose was diluted 1:1 with water. Blood samples and urine were collected for 72 hours post-dose. Adverse effects were assessed at each blood collection time-point using a self-administered questionnaire. Plasma was assayed for oxcarbazepine and monohydroxy derivative; urine was assayed for monohydroxy derivative and monohydroxy derivative-glucuronide. Maximum plasma concentration (Cmax) and time to reach Cmax (tmax) were obtained directly from the plasma concentration-time curves. The areas under the concentration-time curve (AUCs) were determined via noncompartmental analysis. Relative bioavailability was calculated and the Cmax and AUCs were compared using Wilcoxon signed-rank tests. Results: Mean relative bioavailability calculated from plasma AUCs was 8.3% (SD 5.5%) for the monohydroxy derivative and 10.8% (SD 7.3%) for oxcarbazepine. Oxcarbazepine and monohydroxy derivative Cmax and AUC values were significantly lower following rectal administration (p < 0.01). The total amount of monohydroxy derivative excreted in the urine following rectal administration was 10 ± 5% of the amount excreted following oral administration. Oral absorption was consistent with previous studies. The most common adverse effects were headache and fatigue with no discernible differences between routes. Conclusions: Monohydroxy derivative bioavailability following rectal administration of oxcarbazepine suspension is significantly lower than following oral administration, most likely because of poor oxcarbazepine water solubility. It is unlikely that adequate monohydroxy derivative concentrations can be achieved with rectal administration of diluted oxcarbazepine suspension.

UR - http://www.scopus.com/inward/record.url?scp=33947331702&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33947331702&partnerID=8YFLogxK

U2 - 10.2165/00044011-200727040-00003

DO - 10.2165/00044011-200727040-00003

M3 - Article

C2 - 17358096

AN - SCOPUS:33947331702

VL - 27

SP - 243

EP - 250

JO - Clinical Drug Investigation

JF - Clinical Drug Investigation

SN - 0114-2402

IS - 4

ER -