Trade Names:Neurontin- Tablets 600 mg- Tablets 800 mg- Capsules 100 mg- Capsules 300 mg- Capsules 400 mg- Oral solution 250 mg per 5 mLApo-Gabapentin (Canada)CO Gabapentin (Canada)Gen-Gabapentin (Canada)Novo-Gabapentin (Canada)PMS-Gabapentin (Canada)ratio-Gabapentin (Canada)
Mechanism unknown; structurally related to GABA, but does not react with GABA receptors.
Bioavailability decreases as dose increases: bioavailability is approximately 60%, 47%, 34%, 33%, and 27% following 900, 1,200, 2,400, 3,600, and 4,800 mg/day given in 3 divided doses, respectively. Food has only a slight effect on rate and extent of absorption (14% increase in AUC and C max ).
Less than 3% bound to plasma proteins. Vd is approximately 58 L.
Not significantly metabolized in humans.
Excreted unchanged in urine. Half-life is 5 to 7 h.
In CrCl less than 30 mL/min, half-life is approximately 52 h.Hepatic Function Impairment
Studies have not been performed.Elderly
Renal Cl decreases as a result of age-related decline in renal function.Children
Children between 1 mo and younger than 5 yr of age achieved approximately 30% lower exposure (AUC) than that observed in those 5 yr of age and older. Gabapentin elimination half-life averaged 4.7 h and was similar across the age groups studied. Higher oral Cl values were observed in children younger than 5 yr of age compared with those observed in children 5 yr of age and older, when normalized per body weight. The Cl was highly variable in infants younger than 1 yr of age.Hemodialysis
The half-life is approximately 132 h on nondialysis days; during dialysis, half-life is reduced to 3.8 h. Gabapentin is significantly removed by hemodialysis.
Adjunctive therapy in treatment of partial seizures with or without secondary generalization in patients older than 12 yr of age with epilepsy; adjunctive therapy for partial seizures in children 3 to 12 yr of age; management of postherpetic neuralgia in adults.
Agitation in dementia; alcohol withdrawal; bipolar disorder; cocaine withdrawal; diabetic neuropathy; fibromyalgia; headaches; hiccups (singultus); hot flashes (cancer- and/or postmenopausal-related); hyperhidrosis; nausea (cancer-related); neuralgia/neuropathy/chronic pain; prevention of migraine; pruritus (brachioradial/cholestatic/uremic); rectal administration; restless leg syndrome; tremors in multiple sclerosis.
PO 300 mg 3 times daily initially. May increase as necessary to 900 to 1,800 mg/day (divided 3 times daily).Children 5 to 12 yr of age
PO Initiate therapy at 10 to 15 mg/kg/day in 3 divided doses and titrate dose upward over a period of approximately 3 days to effective dose. Effective dose is 25 to 35 mg/kg/day in 3 divided doses.Children 3 to 4 yr of age
PO Initiate therapy at 10 to 15 mg/kg/day in 3 divided doses and titrate dose upward over a period of approximately 3 days to effective dose. Effective dosage is 40 mg/kg/day in 3 divided doses.Postherpetic NeuralgiaAdults
PO Start with a single 300 mg dose on day 1, 600 mg on day 2 (divided twice daily), and 900 mg on day 3 (divided 3 times daily). Subsequently, titrate the dose upward as needed for pain relief to a daily dose of 1,800 mg (divided 3 times daily).Dosage Adjustment for Renal Function ImpairmentAdults and Children older than 12 yr of age CrCl 60 mL/min or higher
Total daily dose range 900 to 3,600 mg/day.CrCl 30 to 59 mL/min
Total daily dose range 400 to 1,400 mg/day.CrCl 16 to 29 mL/min
Total daily dose range 200 to 700 mg/day.CrCl 15 mL/min
Total daily dose range 100 to 300 mg/day.CrCl less than 15 mL/min
Reduce dose in proportion to CrCl (eg, patients with CrCl 7.5 mL/min should receive half the daily dose of patients with CrCl 15 mL/min).Patients on hemodialysis
Maintenance doses based on CrCl as recommended, plus a supplemental posthemodialysis dose administered after each 4 h of hemodialysis as follows: If maintenance dose is 100 mg daily, postdialysis dose is 125 mg; if maintenance dose is 125 mg daily, postdialysis dose is 150 mg; if maintenance dose is 150 mg daily, postdialysis dose is 200 mg; if maintenance dose is 200 mg daily, postdialysis dose is 250 mg; if maintenance dose is 300 mg daily, postdialysis dose is 350 mg.
Store tablets and capsules at 59° to 86°F. Store oral solution at 36° to 46°F.
May reduce bioavailability of gabapentin. Gabapentin should be taken 2 h after antacid.Cimetidine
Renal Cl of gabapentin may be reduced slightly. This interaction is not expected to be clinically important.Hormonal contraceptives
Norethindrone plasma levels may be increased 13%, which is not expected to be clinically important.Hydrocodone
The AUC of gabapentin may be increased by 14% while the hydrocodone C max and AUC are decreased by gabapentin in a dose-dependent manner. Observe the clinical response of the patient when starting, stopping, or changing the gabapentin dose. If an interaction is suspected, adjust the hydrocodone dose as needed.Morphine
The AUC of gabapentin may be increased by morphine. The magnitude of this interaction at various gabapentin doses has not been evaluated. Observe the clinical response of the patient when starting, stopping, or changing the gabapentin dose. If an interaction is suspected, adjust the gabapentin dose as needed.Naproxen
In lower than therapeutic doses, gabapentin absorption was increased 12% to 15% by naproxen. The magnitude of this interaction within the recommended dose ranges of either drug is not known. Observe the clinical response of the patient when starting, stopping, or changing the dose of either drug. If an interaction is suspected, adjust the gabapentin dose as needed.
False-positive readings for Ames N-Multistix SG dipstick test when gabapentin is added to other antiepileptic drugs. Sulfosalicylic acid precipitation procedure is recommended to determine the presence of urine protein.
Hypertension (at least 1%); vasodilation (1%);
Dizziness (28%); somnolence (21%); ataxia (13%); fatigue (11%); hostility, nystagmus (8%); tremor (7%); asthenia (6%); emotional lability (4%); abnormal thinking, headache, hyperkinesia (3%); abnormal gait, amnesia, depression, dysarthria, incoordination, nervousness (2%); anxiety, confusion, malaise, paresthesia, vertigo (at least 1%); abnormal coordination, hypesthesia, twitching (1%); aura disappeared, occipital neuralgia, sleepwalking; movement disorder (postmarketing).
Abrasion, pruritus, rash (1%); erythema multiforme, Stevens-Johnson syndrome (postmarketing).
Diplopia (6%); amblyopia, rhinitis (4%); pharyngitis (3%); abnormal vision (at least 1%); conjunctivitis, otitis media (1%).
Nausea/vomiting (8%); diarrhea (6%); dry mouth (5%); constipation (4%); abdominal pain (3%); dental abnormalities, dry mouth or throat, dyspepsia, flatulence (2%); anorexia, gingivitis (at least 1%); increased appetite (1%).
Impotence (2%); breast hypertrophy (postmarketing).
Purpura (at least 1%); decreased WBC, leukopenia (1%); coagulation defect.
Hepatitis; elevated LFTs, jaundice (postmarketing).
Peripheral edema (8%); weight gain (3%); hyperglycemia (1%); dehydration; blood glucose fluctuations, hyponatremia (postmarketing).
Back pain, myalgia (2%); arthralgia, decreased or absent reflexes, increased reflexes (at least 1%); fracture (1%).
Bronchitis, respiratory infection (3%); coughing (2%); pneumonia (at least 1%); hoarseness, pseudocroup.
Viral infection (11%); fever (10%); infection (5%); accidental injury (3%); face edema (at least 1%); infectious mononucleosis; angioedema (postmarketing).
Monitor patients for clinical worsening, suicidality, and unusual changes in behavior, especially during the first few months of therapy or at times of dose changes (either increases or decreases), and during discontinuation of therapy.
Category C .
Excreted into breast milk.
Effectiveness as adjunctive therapy in the treatment of partial seizures in children younger than 3 yr of age not established; safety and efficacy in management of postherpetic neuralgia in children not established.
Because of age-related renal impairment, adjust dose based on CrCl.
Adjust dose based on CrCl.
May have carcinogenic potential.
May cause dizziness, drowsiness, and other symptoms of CNS depression.
Emotional lability, hostility, thought disorders, and hyperkinesia have been reported with increased frequency in patients 3 to 12 yr of age with epilepsy.
During clinical trials, some patients experienced status epilepticus, and 8 sudden, unexplained deaths occurred. The association of these reactions with gabapentin use is unclear.
Increased risk of suicidal thinking and behavior in patients taking antiepileptic drugs for any indication.
Do not discontinue antiepileptic drugs abruptly because of possible increased seizure frequency from drug withdrawal.
Diarrhea, double vision, drowsiness, lethargy, slurred speech.
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