Anticonvulsant Interactions:PI-Carbamazepine (CBZ)

• Therapeutic failure with Indinavir:

  • 48 year old male on AZT, 3TC, indinavir, VLអ, received CBZ 200 mg/d for post-herpetic neuralgia
  • IDV levels ¯ to 4-25% of mean population values, viral breakthrough occurred

• Toxicity with Ritonavir:

  • 70-85% increase in CBZ levels when RTV added to a pediatric patient stabilized on CBZ
  • separate case report of CBZ-related ataxia with combination

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Hugen PWH, Burger DM, Brinkman K, ter Hofstede HJM, Schuurman R, Koopmans PP, et al. Carbamazepine-indinavir interaction causes antiretroviral therapy failure. Ann Pharmacother 2000;34:465-70.

Report of antiretroviral failure with concomitant CBZ-indinavir therapy. ¯ IDV levels to 4-25% of mean population values. Patient later experienced viral breakthrough.

Kato Y, Fujii T, Mizoguchi N, Takata N, Ueda K, Feldman MD, et al. Potential interaction between ritonavir and carbamazepine. Pharmacother 2000;20:851-4

Addition of ritonavir (200-600 mg per day) to a pediatric patient stabilized on CBZ resulted in 70-85% ? serum CBZ levels. Ritonavir concentrations were not measured.

Berbel GA, Latorre IA, Porta EJ, et al. Protease inhibitor-induced carbamazepine toxicity. Clin Neuropharmacol 2000;23:216-8.

Combination resulted in CBZ-related ataxia. Avoid combination if possible.