DESCRIPTION
Gabapentin – Gabapentin (brand name Neurontin) is a medication originally developed for the treatment of epilepsy. Presently, gabapentin is widely used to relieve pain, especially neuropathic pain. Gabapentin is well tolerated in most patients, has a relatively mild side-effect profile, and passes through the body unmetabolized. Methylcobalamin -Methylcobalamin (mecobalamin, MeCbl, or MeB12) is a cobalamin, a form of vitamin B12. It differs from cyanocobalamin in that the cyanide is replaced by a methyl group.
CATEGORIES
Gabapentin – Anti-Anxiety Agents,Antiparkinson Agents,Analgesics,Anticonvulsants,Calcium Channel Blockers,Antimanic Agents,Excitatory Amino Acid Antagonists. Methylcobalamin – Vitamins .
CHEMICAL FORMULA
Gabapentin – C9H17NO2 , Methylcobalamin – C63H91CoN13O14P .
COMPOSITION
Gabepentin 300mg + Mecthylcobalamin 500mcg
INDICATION
Gabapentin – For the management of postherpetic neuralgia in adults and as adjunctive therapy in the treatment of partial seizures with and without secondary generalization in patients over 12 years of age with epilepsy. Methylcobalamin – It is used to prevent and treat low vitamin B12. Lack of vitamin B12 may cause anemia and damage to the nerves. It is used to treat diabetic neuropathy and peripheral neuropathy.
PHARMACODYNAMICS
Gabapentin – Gabapentin, an analog of GABA, is used as an anticonvulsant to treat partial seizures, amyotrophic lateral sclerosis (ALS), and painful neuropathies. Potential uses include monotherapy of refractory partial seizure disorders, and treatment of spasticity in multiple sclerosis, tremor. mood disorders, and attenuation of disruptive behaviors in dementia. Gabapentin has high lipid solubility, is not metabolized by the liver, has no protein binding, and doesn’t possess the usual drug interactions.
MECHANISM
Gabapentin – Gabapentin interacts with cortical neurons at auxillary subunits of voltage-sensitive calcium channels. Gabapentin increases the synaptic concentration of GABA, enhances GABA responses at non-synaptic sites in neuronal tissues, and reduces the release of mono-amine neurotransmitters. One of the mechanisms implicated in this effect of gabapentin is the reduction of the axon excitability measured as an amplitude change of the presynaptic fibre volley (FV) in the CA1 area of the hippocampus. This is mediated through its binding to presynaptic NMDA receptors. Other studies have shown that the antihyperalgesic and antiallodynic effects of gabapentin are mediated by the descending noradrenergic system, resulting in the activation of spinal alpha2-adrenergic receptors. Gabapentin has also been shown to bind and activate the adenosine A1 receptor.
ABSORPTION
Gabapentin – Rapid. Absorbed in part by the L-amino acid transport system, which is a carrier-mediated, saturable transport system; as the dose increases, bioavailability decreases. Bioavailability ranges from approximately 60% for a 900 mg dose per day to approximately 27% for a 4800 milligram dose per day. Food has a slight effect on the rate and extent of absorption of gabapentin (14% increase in AUC).
VOLUME DISTRIBUTION
Gabapentin – 58±6 L,
METABOLISM
Gabapentin – All pharmacological actions following gabapentin administration are due to the activity of the parent compound; gabapentin is not appreciably metabolized in humans.
ELIMINATION
Gabapentin – Gabapentin is eliminated from the systemic circulation by renal excretion as unchanged drug. Gabapentin is not appreciably metabolized in humans.
HALF LIFE
Gabapentin – 5-7 hours ,
TOXICITY
Gabapentin – Symptoms of overdose include ataxia, labored breathing, ptosis, sedation, hypoactivity, and excitation.
FOOD INTERACTIONS
avoid alcohol
SIDE EFFECTS
Gabapentin – Feeling lightheaded, sleepy, having blurred eyesight, or a change in thinking clearly. Avoid driving and doing other tasks or actions that call for you to be alert or have clear eyesight until you see how this drug affects you. Feeling dizzy. Rise slowly over a few minutes when sitting or lying down. Be careful climbing. Change in balance. Shakiness. Weight gain. Swelling in the arms or legs. Problems with how one acts. Emotional ups and downs. Upset stomach or throwing up. Many small meals, good mouth care, sucking hard, sugar-free candy, or chewing sugar-free gum may help. Hostility. Methylcobalamin – Headache, nausea, vomiting, diarrhea, loss of appetite, skin rash, hot flushes .