Abstracts

Rationale: There are many newer preparations of carbamazepine (CBZ) and its derivative. While these offer multiple choices to clinicians, it is not clear how the various preparations compare, and what advantages or disadvantages one may have over another. Our objective was to compare among the various CBZ-related medications available and identify any potential differentiating factors Methods: We reviewed the information from the package inserts for Tegretol (carbamazepine, CBZ), Tegretol-XR (carbamazepine), Carbatrol (carbamazepine), Trileptal (oxcarbazepine, OXC), Oxtellar (oxcarbazepine), and Aptiom (eslicarbazepine acetate, ESL). Cost is the Average Wholesale Price. Results: 1. There are no significant differences in the following parameters: efficacy, mechanism of action, pregnancy category, incidence of hyponatremia, incidence of rash, or FDA indication for epilepsy type and age. 2. The following may distinguish among the various products: Active molecules: CBZ, OXC, ESL. Protein binding: 76% for CBZ, 40% for OXC and ESL. Liver inducer: CBZ strong inducer, OXC mild inducer, ESL mild inducer and inhibitor. ESL has a unique effect on thyroid function tests. Titration: slowest for CBZ, approximately a week for OXC and ESL. Non-epilepsy indication: only CBZ has one (trigeminal neuralgia). Once daily dosing: Carbatrol, Tegretol-XR, Oxtellar and Aptiom. Effect of food: CBZ is to be taken with food, Oxtellar on an empty stomach. OXC and ESL are unaffected. Monotherapy: CBZ and OXC have an indication. Liquid formulation: available for Tegretol, Trileptal and Oxtellar. Cost: - Average wholesale price (daily cost at 1,200 mg daily) from lowest to highest: generic CBZ $2.70, Carbatrol $8.52, generic OXC $10.12, brand Tegretol $10.80, Tegretol-XR $10.98, Oxtellar $19.80, Trileptal $23.96, Aptiom $47.96. - Retail cash price (monthly at 1200 mg daily): from lowest to highest: generic CBZ $10-20, generic OXC $39-112, Carbatrol $227-241, Tegretol-XR $254-306, Trileptal $527-628, Oxtellar $528-544, Aptiom $638-657. Conclusions: Overall, there are few and relatively minor differentiating features among the various CBZ-related preparations. For selected patients, one may offer advantages over another. Cost may be the most significant one. AWP is the price to pharmacy and may not reflect the cost to patient. Cost varies with multiple factors, including dose, formulation, geography, and insurance type.