Gabapal
Gabapal Uses, Dosage, Side Effects, Food Interaction and all others data.
Gabapentin is an anti-convulsant. It is a structural analog of gamma-amino-butyric-acid (GABA). All pharmacological actions following administration of Gabapentin are due to the activity of parent compound. Gabapentin binds with the alpha-2-delta subunit of voltage gated L-type Calcium channel, and inhibits branched chain amino acid transferase & probably inhibits neurotransmitter release of excitatory amino acid.
Gabapentin is an anti-convulsant medication that inhibits the release of excitatory neurotransmitters, allowing for its use against pathologic neurotransmission such as that seen in neuropathic pain and seizure disorders. It has a wide therapeutic index, with doses in excess of 8000 mg/kg failing to cause a fatal reaction in rats.
Gabapentin is ineffective in absence seizures and should be used in caution in patients with mixed seizure disorders involving absence seizures. Gabapentin has been associated with drug reaction with eosinophilia and systemic symptoms (DRESS), otherwise known as multi-organ hypersensitivity. This reaction can prove fatal and early symptoms such as fever, lymphadenopathy, and rash should be promptly investigated.
| Trade Name | Gabapal |
| Generic | Gabapentin + lidocaine hydrochloride |
| Type | Kit |
| Therapeutic Class | |
| Manufacturer | |
| Available Country | United States |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
Gabapentin is used for-
- Epilepsy
- Neuropathic pain (e.g. postherpetic neuralgia) and other pain conditions
- Bipolar disorder
- Headache syndrome
- Spasticity in multiple sclerosis and spinal cord diseases
Others indication are:
- Alcohol withdrawal
- Schizoaffective disorder
- Post-traumatic stress disorder
- Agitation and behavioural disturbances
- associated with dementia
- Lesch-Nyhan syndrome
- Essential tremor
- Restless legs syndrome
- Brachioradial pruritus
- Hemichorea/hemiballismus
- Hot Flashes
Gabapal is also used to associated treatment for these conditions: Partial-Onset Seizures, Peripheral Neuropathic Pain, Postherpetic Neuralgia
How Gabapal works
The precise mechanism through which gabapentin exerts its therapeutic effects is unclear. The primary mode of action appears to be at the auxillary α2δ-1 subunit of voltage-gated calcium channels (though a low affinity for the α2δ-2 subunit has also been reported). The major function of these subunits is to facilitate the movement of pore-forming α1 subunits of calcium channels from the endoplasmic reticulum to the cell membrane of pre-synaptic neurons. There is evidence that chronic pain states can cause an increase in the expression of α2δ subunits and that these changes correlate with hyperalgesia. Gabapentin appears to inhibit the action of α2δ-1 subunits, thus decreasing the density of pre-synaptic voltage-gated calcium channels and subsequent release of excitatory neurotransmitters. It is likely that this inhibition is also responsible for the anti-epileptic action of gabapentin.
There is some evidence that gabapentin also acts on adenosine receptors and voltage-gated potassium channels, though the clinical relevance of its action at these sites is unclear.
Dosage
Gabapal dosage
Neuropathic pain: 300 mg on day-1, then 300 mg twice on day-2, then 300 mg thrice on day-3, then increase the dose according to response in steps of 300 mg daily to maximum 1800 mg daily in three divided doses.
Partial seizure/epilepsy: 300 mg on day-1, then 300 mg twice on day-2, then 300 mg thrice on day-3, then increase the dose according to response in steps of 300 mg daily to maximum 2400 mg daily in three divided doses.
In case of children:
- For 3-12 years: 10 to 15 mg/kg, Incase of titration 25-35 mg/kg daily in 3 divided doses.
- Maintenance dose is 900 mg daily (body weight 26-36 Kg) or 1.2 gm daily (body weight 37-50 Kg).
Gabapentin can be taken orally with or without food.
Side Effects
Generally Gabapentin is well tolerated but a few side effects like fatigue, dizziness , ataxia, weight gain, peripheral edema, dry mouth and somnolence, may occur. Rarely it may cause fulminate hepatic failure, or aplasticanemia.
Toxicity
The oral TDLo of gabapentin in humans is 2.86 mg/kg and the LD50 in rats has been found to be >8000 mg/kg. Symptoms of overdose are consistent with the drug's adverse effect profile and involve CNS depression (e.g. dizziness, drowsiness, slurred speech, lethargy, loss of consciousness) and gastrointestinal symptoms such as diarrhea. Management of overdose should involve symptomatic and supportive treatment. Gabapentin can be removed by hemodialysis - this may be of benefit in some patients, such as those with impaired renal function.
Multi-drug overdoses involving gabapentin, particularly in combination with other CNS depressants such as opioids, can result in coma and death - this possibility should be considered when managing overdosage.
Precaution
Patients should be instructed to take Gabapentin only as prescribed. While using Gabapentin patients should be instructed either not to drive a car or to operate other complex machinery until they have gained sufficient experiences about Gabapentin whether or not it affects their mental and/or motor performance adversely.
Interaction
Antacids may reduce the bioavailability of Gabapentin by up to 20%. Cimetidine may alter its reanal excretion. Gabapentin does not interact with other anti-epileptic drug or with oral contraceptive preparations.
Volume of Distribution
The apparent volume of distribution of gabapentin after IV administration is 58±6 L. The drug is found in the CSF in concentrations approximately 9-20% of the corresponding plasma concentrations and is secreted into breast milk in concentrations similar to that seen in plasma.
Elimination Route
Absorption of gabapentin is thought to occur solely via facilitated transport by the LAT1 transporter within the intestines. As this process is saturable, the oral bioavailability of gabapentin is inversely proportional to the administered dose - the oral bioavailability of a 900mg/day regimen is approximately 60%, whereas a 4800mg/day regimen results in only 27% bioavailability. The Tmax of gabapentin has been estimated to be 2-3 hours. Food has no appreciable effect on gabapentin absorption.
Clearance
Both the plasma clearance and renal clearance of gabapentin are directly proportional to the patient's creatinine clearance due to its primarily renal elimination.
Elimination Route
Gabapentin is eliminated solely in the urine as unchanged drug. Cimetidine, an inhibitor of renal tubular secretion, reduces clearance by approximately 12%, suggesting that some degree of tubular secretion is involved in the renal elimination of gabapentin.
Pregnancy & Breastfeeding use
Pregnancy: Gabapentin is a pregnancy category C drug; it should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Lactation: Gabapentin may be secreted through the breast milk like many other drugs , so it should be used in women who are nursing, only if the benefits clearly outweigh the risks.
Contraindication
Gabapentin is contraindicated in patients who have known hypersensitivity to the drug.
Special Warning
Use in Children: Safety and effectiveness of Gabapentin in the management of neuropathic pain in pediatric patients have not been established. Safety and effectiveness of Gabapentin in the management of seizures in pediatric patients below the age of 3 years have not been established.
Renal impaired patient: In case of renal impaired patient Gabapentin doses must be reduced :
- CrCl >60 ml/min: 1200 mg/daily in 3 divided doses
- CrCl 30-60 ml/min: 600 mg/daily in 2 divided doses
- CrCl 15-30 ml/min: 300 mg/daily single dose
- CrCl <15 ml/min: 150 mg/daily single dose or 300 mg/every alternate day
- Heamodialysis: maximum 300 mg after each dialysis Gabapentin can be taken orally with or without food.
Storage Condition
Tablets should be stored below 25° C and protected from light & moisture
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