In addition to the adverse experiences reported during clinical testing of Neurontin, the following adverse experiences have been reported in patients receiving marketed Neurontin. These adverse experiences have not been listed above and data are insufficient to support an estimate of their incidence or to establish causation. The listing is alphabetized: angioedema, blood glucose fluctuation, breast hypertrophy, erythema multiforme, elevated liver function tests, fever, hyponatremia, jaundice, movement disorder, Stevens-Johnson syndrome.
Adverse events following the abrupt discontinuation of gabapentin have also been reported. The most frequently reported events were anxiety, insomnia, nausea, pain and sweating.
The abuse and dependence potential of Neurontin has not been evaluated in human studies.
A lethal dose of gabapentin was not identified in mice and rats receiving single oral doses as high as 8000 mg/kg. Signs of acute toxicity in animals included ataxia, labored breathing, ptosis, sedation, hypoactivity, or excitation.
Acute oral overdoses of Neurontin up to 49 grams have been reported. In these cases, double vision, slurred speech, drowsiness, lethargy and diarrhea were observed. All patients recovered with supportive care.
Gabapentin can be removed by hemodialysis. Although hemodialysis has not been performed in the few overdose cases reported, it may be indicated by the patient’s clinical state or in patients with significant renal impairment.
Neurontin is given orally with or without food. Patients should be informed that, should they break the scored 600 or 800 mg tablet in order to administer a half-tablet, they should take the unused half-tablet as the next dose. Half-tablets not used within several days of breaking the scored tablet should be discarded.
If Neurontin dose is reduced, discontinued or substituted with an alternative medication, this should be done gradually over a minimum of 1 week (a longer period may be needed at the discretion of the prescriber).
In adults with postherpetic neuralgia, Neurontin therapy may be initiated as a single 300-mg dose on Day 1, 600 mg/day on Day 2 (divided BID), and 900 mg/day on Day 3 (divided TID). The dose can subsequently be titrated up as needed for pain relief to a daily dose of 1800 mg (divided TID). In clinical studies, efficacy was demonstrated over a range of doses from 1800 mg/day to 3600 mg/day with comparable effects across the dose range. Additional benefit of using doses greater than 1800 mg/day was not demonstrated.
Neurontin is recommended for add-on therapy in patients 3 years of age and older. Effectiveness in pediatric patients below the age of 3 years has not been established.
Patients >12 years of age: The effective dose of Neurontin is 900 to 1800 mg/day and given in divided doses (three times a day) using 300 or 400 mg capsules, or 600 or 800 mg tablets. The starting dose is 300 mg three times a day. If necessary, the dose may be increased using 300 or 400 mg capsules, or 600 or 800 mg tablets three times a day up to 1800 mg/day. Dosages up to 2400 mg/day have been well tolerated in long-term clinical studies. Doses of 3600 mg/day have also been administered to a small number of patients for a relatively short duration, and have been well tolerated. The maximum time between doses in the TID schedule should not exceed 12 hours.
Pediatric Patients Age 3–12 years: The starting dose should range from 10–15 mg/kg/day in 3 divided doses, and the effective dose reached by upward titration over a period of approximately 3 days. The effective dose of Neurontin in patients 5 years of age and older is 25–35 mg/kg/day and given in divided doses (three times a day). The effective dose in pediatric patients ages 3 and 4 years is 40 mg/kg/day and given in divided doses (three times a day) (see CLINICAL PHARMACOLOGY, Pediatrics.) Neurontin may be administered as the oral solution, capsule, or tablet, or using combinations of these formulations. Dosages up to 50 mg/kg/day have been well-tolerated in a long-term clinical study. The maximum time interval between doses should not exceed 12 hours.
It is not necessary to monitor gabapentin plasma concentrations to optimize Neurontin therapy. Further, because there are no significant pharmacokinetic interactions among Neurontin and other commonly used antiepileptic drugs, the addition of Neurontin does not alter the plasma levels of these drugs appreciably.
If Neurontin is discontinued and/or an alternate anticonvulsant medication is added to the therapy, this should be done gradually over a minimum of 1 week.
Creatinine clearance is difficult to measure in outpatients. In patients with stable renal function, creatinine clearance (CCr ) can be reasonably well estimated using the equation of Cockcroft and Gault:
for females CCr =(0.85)(140-age)(weight)/[(72)(SCr )]
for males CCr =(140-age)(weight)/[(72)(SCr )]
where age is in years, weight is in kilograms and SCr is serum creatinine in mg/dL.
Dosage adjustment in patients ≥12 years of age with compromised renal function or undergoing hemodialysis is recommended as follows (see dosing recommendations above for effective doses in each indication).
|Renal Function Creatinine Clearance (mL/min)||Total Daily Dose Range (mg/day)||Dose Regimen(mg)|
|≥60||900–3600||300 TID||400 TID||600 TID||800 TID||1200 TID|
|>30–59||400–1400||200 BID||300 BID||400 BID||500 BID||700 BID|
|>15–29||200–700||200 QD||300 QD||400 QD||500 QD||700 QD|
|15*||100–300||100 QD||125 QD||150 QD||200 QD||300 QD|
|Post-Hemodialysis Supplemental Dose (mg)†|
The use of Neurontin in patients <12 years of age with compromised renal function has not been studied.
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