No

Anticonvulsant, Miscellaneous

Adjunct for treatment of partial seizures with and without secondarily generalized seizures in adults with epilepsy

C

Clinical effects on the fetus: No data on crossing the placenta; 4 reports of normal pregnancy outcomes; 1 report of infant with respiratory distress, pyloric stenosis, inguinal hernia following 1st trimester exposure to gabapentin plus carbamazepine; epilepsy itself, number of medications, genetic factors, or a combination of these probably influence the teratogenicity of anticonvulsant therapy

Breast-feeding/lactation: No data available

Hypersensitivity to gabapentin or its ingredients

Avoid abrupt withdrawal, may precipitate seizures; may be associated with a slight incidence (0.6%) of status epilepticus and sudden deaths (0.0038 deaths/patient year); use cautiously in patients with severe renal dysfunction; rat studies demonstrated an association with pancreatic adenocarcinoma in male rats; clinical implication unknown. May cause CNS depression, which may impair physical or mental abilities. Patients must be cautioned about performing tasks which require mental alertness (ie, operating machinery or driving). Effects with other sedative drugs or ethanol may be potentiated.

>10%: Central nervous system: Somnolence, dizziness, ataxia, fatigue

1% to 10%:

Cardiovascular: Peripheral edema

Central nervous system: Nervousness, amnesia, depression, abnormal coordination, dysarthria, abnormal thinking, twitching

Dermatologic: Pruritus

Gastrointestinal: Dyspepsia, xerostomia, dry throat, constipation, appetite stimulation (weight gain)

Genitourinary: Impotence

Hematologic: Leukopenia

Neuromuscular & skeletal: Back pain, myalgia, tremor

Ocular: Diplopia, blurred vision, nystagmus

Respiratory: Rhinitis, pharyngitis, coughing

Decontaminate using lavage/activated charcoal with cathartic

Multiple dosing of activated charcoal may be useful; hemodialysis will be useful

Gabapentin does not modify plasma concentrations of standard anticonvulsant medications (ie, valproic acid, carbamazepine, phenytoin, or phenobarbital)

Antacids reduce the bioavailability of gabapentin by 20%

Cimetidine may decrease clearance (by 14%) of gabapentin; gabapentin may increase C_max of norethindrone by 13%

Exact mechanism of action is not known, but does have properties in common with other anticonvulsants; although structurally related to GABA, it does not interact with GABA receptors

Absorption: Oral: 50% to 60%

Distribution: V_d: 0.6-0.8 L/kg

Protein binding: 0%

Half-life: 5-6 hours

Elimination: Renal, 56% to 80%

If gabapentin is discontinued or if another anticonvulsant is added to therapy, it should be done slowly over a minimum of 1 week

Initial: 300 mg 3 times/day, if necessary the dose may be increased using 300 or 400 mg capsules 3 times/day up to 1800 mg/day

Total daily dosage range: 900-1800 mg/day administered in 3 divided doses at 8-hour intervals

Pain: 300-1800 mg/day given in 3 divided doses has been the most common dosage range

Bipolar disorder: 300-3000 mg/day given in 3 divided doses

Dosing adjustment in renal impairment:

Cl_cr >60 mL/minute: Administer 1200 mg/day

Cl_cr 30-60 mL/minute: Administer 600 mg/day

Cl_cr 15-30 mL/minute: Administer 300 mg/day

Cl_cr <15 mL/minute: Administer 150 mg/day

Hemodialysis: 200-300 mg after each 4-hour dialysis following a loading dose of 300-400 mg

Food: Does not change rate or extent of absorption; take without regard to meals

Serum lipids: May see increases in total cholesterol, HDL cholesterol and triglycerides. Hyperlipidemia and hypercholesterolemia have been reported with gabapentin.

Monitor serum levels of concomitant anticonvulsant therapy; routine monitoring of gabapentin levels is not mandatory

Minimum effective serum concentration may be 2 mg/mL; routine monitoring of drug levels is not required

No information available to require special precautions

No effects or complications reported

Take exactly as directed (do not increase dose or frequency or discontinue without consulting prescriber). While using this medication, do not use alcohol and other prescription or OTC medications (especially pain medications, sedatives, antihistamines, or hypnotics) without consulting prescriber. Maintain adequate hydration (2-3 L/day of fluids unless instructed to restrict fluid intake). You may experience drowsiness, dizziness, or blurred vision (use caution when driving or engaging in tasks requiring alertness until response to drug is known); nausea, vomiting, loss of appetite, or dry mouth (small frequent meals, frequent mouth care, chewing gum, or sucking lozenges may help). Wear identification of epileptic status. Report CNS changes, mentation changes, or changes in cognition; muscle cramping, weakness, tremors, changes in gait; persistent GI symptoms (cramping, constipation, vomiting, anorexia); difficulty breathing; impotence or changes in urinary pattern; worsening of seizure activity, or loss of seizure control. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Breast-feeding is not recommended.

Dosage must be adjusted for renal function and elderly often have reduced renal function

Capsule: 100 mg, 300 mg, 400 mg, 600 mg, 800 mg

A 100 mg/mL suspension was stable for 91 days when refrigerated or 56 days when kept at room temperature when compounded as follows:

Vehicle 1. Methylcellulose 1% (100 mL) and Simple Syrup N.F. (100 mL) mixed together in a graduate, or

Vehicle 2. Ora-Sweet® (100 mL) and Ora-Plus® (100 mL) mixed together in a graduate

Shake well before using and keep in refrigerator

Nahata MC, Morosco RS, and Hipple TF, Stability of Gabapentin in Extemporaneously Prepared Suspensions at Two Temperatures, American Society of Health System Pharmacists Midyear Meeting, December 7-11, 1997.

Adler CH, "Treatment of Restless Legs Syndrome With Gabapentin," Clin Neuropharmacol, 1997, 20(2):148-51.

Andrews CO and Fischer JH, "Gabapentin: A New Agent for the Management of Epilepsy," Ann Pharmacother, 1994, 28(10):1188-96.

Bourgeois BF, "Antiepileptic Drugs in Pediatric Practice," Epilepsia, 1995, 36(Suppl 2):S34-45.

Fischer JH, Barr AN, Rogers SL, et al, "Lack of Serious Toxicity Following Gabapentin Overdose," Neurology, 1994, 44(5):982-3.

Goa KL and Sorkin EM, "Gabapentin: A Review of Its Pharmacological Properties and Clinical Potential in Epilepsy," Drugs, 1993, 46(3):409-27.

Khurana DS, Riviello J, Helmers S, et al, "Efficacy of Gabapentin Therapy in Children With Refractory Partial Seizures," J Pediatr, 1996, 128(6):829-33.

Lee DO, Steingard RJ, Cesena M, et al, "Behavioral Side Effects of Gabapentin in Children," Epilepsia, 1996, 37(1):87-90.

Leiderman D, Garofalo E, and LaMoreaux L, "Gabapentin Patients With Absence Seizures: Two Double-Blind, Placebo Controlled Studies," Epilepsia, 1993, 34(Suppl 6):45 (abstract).

Mellick LB and Mellick GA, "Successful Treatment of Reflex Sympathetic Dystrophy With Gabapentin," Am J Emerg Med, 1995, 13(1):96.

Short C and Cooke L, "Hypomania Induced by Gabapentin," Br J Psychiatry, 1995, 166(5):679-80.