Gapentin

Gapentin

gabapentin

Manufacturer:

Community Pharm PCL

Distributor:

Community Pharm PCL
Full Prescribing Info
Contents
Gabapentin.
Action
Pharmacology: Pharmacodynamics: Mechanism of Action: Gabapentin is structurally related to the neurotransmitter gamma-aminobutyric acid (GABA), but it does not modify GABAA or GABAB radioligand binding. It is not converted metabolically into GABA or a GABA agonist and it is not an inhibitor of GABA uptake or degradation. The mechanism by which gabapentin exerts its analgesic and anticonvulsant effects is unknown. Gabapentin was tested in radioligand binding assays at concentrations up to 100 mcM and did not exhibit affinity for a number of other common receptor sites, including benzodiazepine, glutamate, N-methyl-D-aspartate (NMDA), quisqualate, kainite, strychnine-insensitive or strychnine-sensitive glycine, alpha-1, alpha-2, or beta adrenergic, cannabinoid1, adenosine A1 or A2, cholinergic muscarinic or nicotinic, dopamine D1 or D2, histamine H1, serotonin S1 or S2, opiate mu, delta or kappa, voltage-sensitive calcium channel sites labeled with nitrendipine or diltiazem, or at voltage-sensitive sodium channel sites with batrachotoxinin A 20-alpha-benzoate. Furthermore, gabapentin did not alter the cellular uptake of dopamine, norepinephrine, or serotonin.
Pharmacokinetics:
Gabapentin bioavailability is not dose-propertional (ie, as dose is increased, bioavailability decreases). Bioavailability of gabapentin is approximately 60%, 47%, 34%, 33% and 27% following 900, 1200, 2400, 3600 and 4800 mg/day given in 3 divided doses, respectively. Less than 3% of gabapentin circulates bound to plasma protein. In patients with epilepsy, steady-state predose concentrations of gabapentin in cerebrospinal fluid were approximately 20% of the corresponding plasma concentrations. Gabapentin is eliminated from the systemic circulation by renal excretion as unchanged drug. The elimination half-life of gabapentin is 5 to 7 hours. Gabapentin is unaltered by dose or following multiple dosing. Gabapentin elimination rate constant, plasma clearance and renal clearance are directly proportional to creatinine clearance (CrCl). Gabapentin can be removed from plasma by hemodialysis.
Indications/Uses
Epilepsy: Gabapentin is indicated as an adjunctive therapy in the treatment of partial seizures with and without secondary generalization in patients older than 12 years of age with epilepsy as adjunctive therapy in the treatment of partial seizures in children 3 to 12 years of age.
Neuropathic pain: Postherpetic neuralgia: Gabapentin is used in the management of postherpetic neuralgia (PHN) in adults.
Dosage/Direction for Use
Adult and children over 12 years of age: Epilepsy: Usual dosage: 900 to 1800 mg/day given in divided dose (3 times a day).
Initial dosage: 300 mg 3 time a day.
Dosages titration: If necessary, the dose may be increased using 300 mg capsules 3 times a day up to 1800 mg/day.
Postherpetic neuralgia: Usual dosage: 900 mg/day given as three equally divided doses, and increased if necessary, based on response, up to a maximum dose of 3600 mg/day.
Initial dosage: 300 mg once daily on the first day. 300 mg twice daily on the second day and 300 mg 3 times daily on the third day.
Dosages titration: The dose can subsequently be titrated up as needed for pain relief to a daily dose of 1800 mg (divided 3 times daily).
Children 3-12 years of age: Epilepsy: Usual dosage: Dosages of up to 50 mg/kg/day have been well tolerated in a long-term clinical study.
5 to 12 years of age: 25 to 35 mg/kg/day given in divided doses (3 times a day).
3 and 4 years of age: 40 mg/kg/day given in divided doses (3 times a day).
Initial dosage: 10 to 15 mg/kg/day in 3 divided doses and the effective dose reached by upward titration over a period of approximately 3 days.
Administration: Gabapentin is administered orally. The drug may be administered without regard to meals.
Overdosage
Acute oral overdoses of gabapentin of up to 49 g have been reported. In 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.
Contraindications
Gabapentin is contraindicated in patients who are hypersensitivity to gabapentin or its ingredients.
Warnings
Based on the Ministry of Public Health's Announcement: The drug may cause drowsiness, should not drive a car or operate machinery, or drink alcoholic beverages while taking the drug. The drug may cause hematologic disorder. Do not use the drug in pregnant women because it may cause infant's morbidity. Use the drug with caution in patients with liver and kindly disease.
Special Precautions
Antiepileptic drug (AEDs), including gabapentin, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication.
Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior and/or any unusual changes in mood or behavior.
AEDs should not be abruptly discontinued because of the possibility of increasing seizure frequency.
Use In Pregnancy & Lactation
Pregnancy Category C.
It is not known whether gabapentin crosses the human placenta to the fetus. Because of its lack of protein binding and low molecular weight (approximately 171), exposure of the embryo and fetus should expected. There are no adequate and well-controlled studies in pregnant women. This drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Gabapentin is distributed into milk following oral administration. Because of the potential for serious adverse reactions to gabapentin in nursing infants, the drug should be administered to nursing women only if the potential benefits justify the risk to the infant.
Adverse Reactions
>10%: Central nervous system: Dizziness (17% to 28%; children 3%), somnolence (19% to 21%; children 8%), ataxia (3% to 13%), fatigue (11%; children 3%).
Miscellaneous: Viral infection (children 11%).
1% to 10%: Cardiovascular: Peripheral edema (2% to 8%), vasodilatation (1%).
Central nervous system: Fever (children 10%), hostility (children 5% to 8%), emotional lability (children 4% to 6%), headache, abnormal thinking (2% to 3%; children 2%), amnesia (2%), depression (2%), nervousness (2%), abnormal coordination (1% to 2%), hyperesthesia (1%), twitching (1%).
Dermatologic: Pruritus (1%), rash (1%).
Endocrine and metabolic: Hyperglycemia (1%).
Gastrointestinal: Diarrhea (6%), nausea/vomiting (3% to 4%; children 8%), abdominal pain (3%), xerostomia (2% to 5%), constipation (1% to 4%), weight gain (adult and children 2% to 3%), dyspepsia (2%), flatulence (2%), dry throat (2%), dental abnormalities (2%), appetite stimulation (1%).
Genitourinary: Impotence (2%).
Hematologic: Decreased WBC (1%), leukopenia (1%).
Neuromuscular and skeletal: Tremor (7%), weakness (6%), hyperkinesia (children 3% to 5%), adnormal gait (2%), back pain (2%), dysarthria (2%), limb pain, myalgia (2%), fracture (1%).
Ocular: Nystagmus (8%), diplopia (1% to 6%), blurred vision (3% to 4%), conjunctivitis (1%).
Otic: Otitis media (1%).
Respiratory: Rhinitis (4%), bronchitis (children 3%), nasopharyngitis, respiratory infection (children 3%), pharyngitis (1% to 3%), cough (2%).
Miscellaneous: Infection (5%).
Drug Interactions
Concomitant administration of gabapentin and antacids reduced the bioavailability of gabapentin by approximately 20%. It is recommended that gabapentin be taken about two hours following antacid administration.
Coadministration of gabapentin and controlled-release morphine 60 mg 2 hours prior to administration of gabapentin 600 mg resulted in an increase in gabapentin AUC by 44%. The magnitude of interaction at other doses is unknown.
Coadministration of gabapentin and oral contraceptives containing norethindrone and or ethinyl estradiol does not influence the steady-state pharmacokinetics of either component.
Storage
Store below 30°C.
ATC Classification
N03AX12 - gabapentin ; Belongs to the class of other antiepileptics.
Presentation/Packing
Cap 300 mg (yellow, hard gelatin capsule No. 1, marked
Click on icon to see table/diagram/image
on the cap and "GABA 300" on the body with black ink, filled with white powder) x 3 x 10's.
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