CARBAZEN TABLETS

Indications

• Epilepsy (partial seizures, generalized tonic-clonic seizures)
• Bipolar disorder (acute manic or mixed episodes)
• Trigeminal neuralgia
• Diabetic neuropathy

Dosage

Children: Refer to specific guidelines, as dosing must be determined based on age, weight

Adults: Refer to specific guidelines, as dosing may vary based on condition and patient response.

Mechanism of action

Carbamazepine exerts its therapeutic effects primarily through the inhibition of voltage-gated sodium channels, stabilizing the inactive state of the channels and consequently reducing the release of excitatory neurotransmitters. This results in decreased neuronal firing and seizure control. Additionally, it may influence the release of neurotransmitters such as glutamate and gamma-aminobutyric acid (GABA), contributing to its mood-stabilizing effects.

Pharmacodynamics

Carbamazepine exhibits dose-dependent pharmacodynamics, with its anticonvulsant effects becoming more pronounced at higher doses. It also has analgesic properties, which are particularly useful in treating neuropathic pain. The drug’s effect on mood stabilization is attributed to its ability to modulate neurotransmitter levels and neuronal excitability, making it effective in treating manic and depressive episodes in bipolar disorder.

Pharmacokinetics

Carbamazepine is well absorbed after oral administration, with peak plasma concentrations usually occurring within 4 to 12 hours. It undergoes extensive hepatic metabolism via cytochrome P450 enzymes, specifically CYP3A4, leading to the formation of active metabolites. The drug has a half-life of approximately 12 to 17 hours, but this can be significantly reduced in chronic users due to autoinduction of its own metabolism. Carbamazepine is highly protein-bound (approximately 75-85%) and has a volume of distribution of about 0.8 to 1.5 L/kg.

Contra-indications

• Hypersensitivity to carbamazepine or any of its components
• History of bone marrow suppression
• Concurrent use with monoamine oxidase inhibitors (MAOIs)

Adverse effects

• Dizziness
• Drowsiness
• Nausea
• Vomiting
• Ataxia
• Diplopia
• Rash
• Aplastic anemia
• Stevens-Johnson syndrome

Interactions

• May interact with other antiepileptic drugs, potentially altering their effects
• Can affect the metabolism of warfarin and other anticoagulants
• May reduce the effectiveness of hormonal contraceptives
• Concomitant use with certain antidepressants may increase the risk of serotonin syndrome

Precautions

• Use with caution in patients with a history of liver disease
• Regular monitoring of liver function and complete blood counts is advised
• Caution in patients with a history of drug abuse or dependency
• Gradual withdrawal is recommended to avoid withdrawal seizures

Pregnancy

Carbamazepine is classified as category D in pregnancy. It should only be used if the benefits outweigh the risks, as it may cause fetal harm.

Breast-feeding

Carbamazepine is excreted in breast milk. Caution is advised when administering to breastfeeding mothers, as it may affect the infant.

Storage

Store at room temperature, in a tightly closed container, away from moisture and heat.

Formulations

• Tablets
• Extended-release tablets
• Oral suspension