Gabapentin absorption

Gidal BE, Maly MM, Kowalski J, et al. Gabapentin absorption Effect of mixing with foods of varying macronutrient content. Ann Pharmacother 1998 32 405-408. 

Gidal, B. E. et al.. Inter- and intra-subject variability in gabapentin absorption and absolute bioavailability. Epilepsy Res., 40 123-127, 2000. 

Gidal BE, Maly MH Kowalski JW, Rutecki PA Pitterle ME, Cook DE Gabapentin absorption effect of mixing with foods of varying macronutrient composition Ann Phamacother (1998) 32,405-9. 

BH Stewart, AR Kugler, PR Thompson, NN Bock-brader. A saturable transport mechanism in the intestinal absorption of gabapentin is the underlying cause of the lack of proportionality between increasing dose and drug levels in plasma. Pharmaceut Res 10 276-281, 1993. 

Cundy, K. C., Annamalai, T., Bu, L., et al. XP13512 [( )-l-([(a-isobutanoyloxyethoxy) carbonyl] aminomethyl)-1-cyclohexane acetic acid], a novel gabapentin prodrug II. Improved oral bioavailability, dose proportionality, and colonic absorption compared with gabapentin in rats and monkeys. J. Pharmacol. Exp. Ther. 311 324-333, 2004. 

GABAPENTIN ANTACIDS i gabapentin levels l absorption Separate doses by at least 3 hours... 

Antacids Gabapentin Phenobarbital Phenytoin Reduced effect of the object drugs Reduced absorption of the object drugs... 

In an uncontrolled trial using dosages up to 6000 mg/day in 50 patients with refractory partial epilepsy, tiredness, dizziness, headache, and diplopia were the most common adverse effects (4). At dosages above 3600 mg/day three patients developed flatulence and diarrhea and two had myoclonic jerks. At least in some patients, gabapentin gastrointestinal absorption did not become saturated within the explored dosage range. 

Drug interactions are infrequent with gabapentin. It does not induce hepatic metabolizing enzymes, nor do other AEDs affect its metabolism and elimination. Antacids may decrease absorption. Gabapentin dosage may need to be decreased in patients with renal disease or in the elderly. 

Aluminium/magnesium hydroxide slightly reduces the absorption of gabapentin. 

Food, including protein and enterai feeds, does not have a clinical-iy important effect on the absorption of gabapentin. 

Parnell J, Sheth R, Limdi N, Gidal BE. Oral absorption of gabapentin rup is not impaired by concomitant administration with various beverages or enteral nutrition supplement. Epilepsia (2001) 42 (Suppl 7), 91. 

Drug formulatious Gabapentin has a short half-life and a saturable mechanism of absorption, with consequent lack of proportionality between doses and concentrations. New formulations have therefore been developed. An extended-release formulation may overcome the problems of saturable absorption and short half-life. When administered with a meal, this formulation gradually expands and releases the drug to the upper gastrointestinal tract over an extended period of time. This enables it to be taken once or twice a day compared with three times a day or more for immediate-release gabapentin. 

Gabapentin enaCcU bil is another attempt to overcome the problem of gabapentin saturable absorption. It is a prodrug that is actively transported and provides predictable dose-proportional gabapentin exposure and oral availability of about 70%. 

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