Pharmacokinetics/pharmacodynamics of sodium oxybate
The following describes pertinent pharmacokinetic characteristics of sodium oxybate.
Absorption & distribution
Metabolism & Elimination
Pharmacokinetics of Sodium oxybate: Bottom line:
Potential drug interactions
Absorption & distribution
- Sodium oxybate is rapidly absorbed following ingestion
- Its pharmacokinetics does not appear to be gender-dependent
- Absorption is dose-dependent
- When taken with a high fat meal, the absorption of sodium oxybate was slowed, as observed by reductions in the mean Cmax and AUC
- The mean apparent volume of distribution did not differ significantly between fed and fasted states
- Protein binding is < 1 %, and bioavailability after oral administration is ~25 – 27%, most likely due to high first-pass metabolism
Metabolism & Elimination
- In vitro, sodium oxybate does not significantly inhibit the activity of CYP450 enzymes at concentrations of up to 3 mmol/L
- The elimination of sodium oxybate from circulation is rapid, and the relatively short half life (30 – 60 minutes) necessitates twice nightly administration
- Excretion is primarily pulmonary (as carbon dioxide), with minimal urinary excretion of the drug (<5% as unchanged drug)
Pharmacokinetics of Sodium oxybate: Bottom line:
- Sodium oxybate is rapidly absorbed and has a relatively short half-life, therefore requiring twice-nightly administration (the second dose is taken 2.5 – 4 hours later)
- Absorption is slowed by food, necessitating administration 2 – 3 hours after a meal
- The rapidity of sleep induction by ingestion of sodium oxybate requires patients to take the medication after getting into bed
Potential drug interactions
- No drug interactions have been observed with sodium oxybate and modafinil
- Sodium oxybate may increase the levels or effects of alcohol, zolpidem, SSRIs, and other CNS depressants
- Droperidol, hydroxyzine, and methotrimeprazine may increase the levels of sodium oxybate
References
1) Lexi-Drugs. Lexi-Comp Online 2012.
2) Robinson, Keating. Sodium oxybate- a review of its use in the management of narcolepsy. CNS Drugs 2007
Images:
http://bouldersleeptherapy.com/disorders/narcolepsy.php/
autoimmunediseasesa2z.com
www3.unil.ch
2) Robinson, Keating. Sodium oxybate- a review of its use in the management of narcolepsy. CNS Drugs 2007
Images:
http://bouldersleeptherapy.com/disorders/narcolepsy.php/
autoimmunediseasesa2z.com
www3.unil.ch