Boxed Warnings
Abuse potential or dependence. Gabapentin is a potential drug of abuse and dependence. Gabapentin poses risks of abuse and dependence which can lead to overdose and death especially when used concomitantly with opioids and other CNS depressants. Assess the patient's risk of abuse or dependence before prescribing and monitor the patient regularly during treatment, particularly amongst patients with current or past abuse or dependence of opioids and/or benzodiazepines (see Section 4.4 Special Warnings and Precautions for Use).
1 Name of Medicine
Gabapentin.
2 Qualitative and Quantitative Composition
Gabacor contains the active ingredient gabapentin.
Gabacor 100 mg capsules. Each capsule contains gabapentin 100 mg.
Gabacor 300 mg capsules. Each capsule contains gabapentin 300 mg.
Gabacor 400 mg capsules. Each capsule contains gabapentin 400 mg.
Excipient with known effect. Lactose.
For the full list of excipients, see Section 6.1 List of Excipients.
3 Pharmaceutical Form
Capsules, hard.
Gabacor 100 mg capsules. Size "4" white hard gelatin capsule imprinted "216" on body with blue ink.
Gabacor 300 mg capsules. Size "1" yellow hard gelatin capsule imprinted "215" on body with blue ink.
Gabacor 400 mg capsules. Size "0" orange hard gelatin capsule imprinted "214" on body with blue ink.
4 Clinical Particulars
4.9 Overdose
Signs and symptoms. Symptoms of an overdose included somnolence, ataxia, dizziness, double vision, nystagmus, slurred speech, drowsiness, loss of consciousness, lethargy, mild hypotension and gastrointestinal symptoms including diarrhoea. Gabapentin overdose alone has not been reported to produce significant cardiotoxicity.
Overdoses as high as 108 g have been reported with full recovery following symptomatic therapy. Reduced absorption of gabapentin at higher doses may limit drug absorption at the time of overdosing and, hence, minimise toxicity from overdoses.
Treatment of overdosage. There is no specific antidote for gabapentin; treatment is symptomatic. The patient should be monitored closely and given supportive care where necessary to maintain vital functions. Overdoses may involve other concurrent medications and should be treated accordingly.
Activated charcoal may reduce absorption of the drug if given within one hour after ingestion. In patients who are not fully conscious or have impaired gag reflex, consideration should be given to administering activated charcoal via nasogastric tube once the airway is protected.
Gabapentin can be removed by haemodialysis. Although haemodialysis 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.
Ipecac induced emesis is not recommended because of the potential for CNS depression.
For information on the management of overdose, contact the Poisons Information Centre on 131126 (Australia).
5 Pharmacological Properties
5.3 Preclinical Safety Data
Genotoxicity. There is no evidence that gabapentin has genotoxic potential. It was not mutagenic in vitro in standard assays using bacterial or mammalian cells. Gabapentin did not induce structural chromosome aberrations in mammalian cells in vitro or in vivo, and did not induce micronucleus formation in the bone marrow of hamsters.
Carcinogenicity. Gabapentin was given in the diet to mice at 200, 600, and 2000 mg/kg/day and to rats at 250, 1000 and 2000 mg/kg/day for two years. A statistically significant increase in the incidence of pancreatic acinar cell adenoma and carcinoma was found only in male rats at the highest dose. Peak plasma gabapentin concentrations and areas under the concentration time curve in rats at 2000 mg/kg/day were 14 times higher than plasma concentrations in humans given the recommended maximum tolerated dose of 2400 mg/day. The pancreatic acinar cell tumours in male rats were low grade malignancies, which did not metastasise or invade surrounding tissue, and were similar to those seen in concurrent controls. The relevance of these pancreatic acinar cell tumours in male rats to carcinogenic risk in human is unclear.
6 Pharmaceutical Particulars
6.7 Physicochemical Properties
Gabapentin is a white to off-white crystalline solid. It is freely soluble in water and both basic and acidic aqueous solutions.
The structural formula of gabapentin is shown below:
Chemical structure.
https://stagingapi.mims.com/au/public/v2/images/fullchemgif/CSGABAPE.gif Chemical name: 1-(aminomethyl) cyclohexaneacetic acid.
Molecular formula: C9H17NO2.
Molecular weight: 171.24.
CAS number. CAS Registry Number: 60142-96-3.
7 Medicine Schedule (Poisons Standard)
Schedule 4 - Prescription only medicine.
Summary Table of Changes
https://stagingapi.mims.com/au/public/v2/images/fulltablegif/GABACOST.gif
