Chemical and Pharmaceutical Details
Levetiracetam is chemically described as (-)-(S)-α-ethyl-2-oxo-1-pyrrolidine acetamide, with the molecular formula C8H14N2O2 and molecular weight of 170.21. 1 It is a white to off-white crystalline powder that is very soluble in water and is chemically unrelated to existing antiepileptic drugs. 1
Clinical Context
- Brand name: Keppra (also E Keppra for extended-release formulations) 2
- Drug class: Second-generation antiepileptic drug (AED) 2, 3
- Mechanism: Levetiracetam has a novel mechanism of action involving neuronal binding to synaptic vesicle protein 2A, inhibiting calcium release from intraneuronal stores, and inhibiting N-type calcium channels—distinct from traditional AEDs. 2, 3
Important Prescribing Considerations
Generic substitution may not be therapeutically equivalent in all patients. Case reports document increased breakthrough seizures when patients were switched from brand-name Keppra to generic levetiracetam formulations, with seizure control returning to baseline when Keppra was reinstituted. 4 Additionally, preclinical studies in mice showed significant differences in pharmacokinetic parameters and safety profiles between Keppra and certain generic formulations available in some markets. 5
Pharmacokinetic advantages: Levetiracetam exhibits rapid and complete absorption, high oral bioavailability, minimal metabolism via acetamide hydrolysis, and primarily renal elimination. 2 Critically, it lacks cytochrome P450 enzyme-inducing potential and has no clinically significant pharmacokinetic interactions with other drugs, making it particularly valuable in brain tumor patients on chemotherapy or other medications. 2, 3