Abstract
BACKGROUND: Highly effective and well-tolerated direct-acting antiviral (DAA) therapies have revolutionised the management of hepatitis C virus (HCV); however, niche populations face treatment barriers. DAAs co-prescribed with several first-generation anti-epileptic drugs (AEDs) are contraindicated due to drug-drug interactions. A common example is carbamazepine whereby steady-state carbamazepine reduces the maximum concentration and area under the curve of velpatasvir, glecaprevir and pibrentasvir due to potent cytochrome P450 (CYP) 3A4 induction. Carbamazepine also induces P-glycoprotein which reduces glecaprevir and pibrentasvir's area under curve to infinite time. Sofosbuvir-velpatasvir and glecaprevir-pibrentasvir are contraindicated in patients who are co-prescribed carbamazepine due to the risk of reduced DAA therapeutic effect and consequently, virological treatment failure. This presents a challenge for patients in whom carbamazepine substitution is medically unfeasible, impractical or unacceptable. However, the properties of current generation DAA therapies, including high-potency non-structural protein 5A inhibitory effect, may be sufficient to overcome reduced bioavailability arising from carbamazepine related CYP 3A4 and P-glycoprotein induction. CASE SUMMARY: We present a case series of three patients with non-cirrhotic, treatment-naïve, genotype 1a, 1b, and 3a HCV who were treated with a 12 wk course of glecaprevir-pibrentasvir, while co-prescribed carbamazepine for seizure disorders. Glecaprevir-pibrentasvir combination therapy was chosen due to its potent in vitro activity and low barrier to pan-genotypic resistance associated variants. DAA therapy was dose-separated from carbamazepine to maximise time to peak concentration, and taken with meals to improve absorption. Sustained virological response at 12 wk was achieved in each patient with no adverse outcomes. CONCLUSION: DAA therapies, including glecaprevir-pibrentasvir, warrant consideration as a therapeutic agent in people with HCV who are co-prescribed carbamazepine, particularly if AED substitution is not feasible.