Concomitant Treatment of Tuberculosis and Hepatitis C Virus in Coinfected Patients Using Serum Drug Concentration Monitoring.

Background: Concern for drug-drug interactions leading to treatment failure and drug-resistant strains have discouraged clinicians from attempting concomitant treatment of hepatitis C virus (HCV) and tuberculosis (TB). Increased metabolism of direct-acting antivirals (DAAs) by rifamycins has hindered concurrent use. Development of an assay for ledipasvir and sofosbuvir (LDV/SOF) serum concentrations for therapeutic drug monitoring (TDM) can ensure adequate therapy. We present the first cases of concomitant therapy of active TB and HCV with rifamycin-containing regimens and DAAs using TDM. Methods: Using TDM, we aim to determine whether concomitant therapy with rifamycin-containing regimens and DAAs is safe and effective for patients coinfected with TB and HCV. Five individuals with TB and HCV who experienced transaminitis before or during TB therapy were concomitantly treated with rifamycin-containing regimens and LDV/SOF. Therapeutic drug monitoring was performed for LDV, SOF, and rifabutin during therapy. Baseline laboratory tests and serial liver enzymes were performed. Hepatitis C virus viral load and mycobacterial sputum cultures were obtained upon completion of therapy to determine efficacy of therapy. Results: All patients were found to have nondetectable HCV viral loads and negative mycobacterial sputum cultures upon completion of therapy. No clinically significant adverse effects were reported. Conclusions: These cases illustrate concomitant use of LDV/SOF and rifabutin in patients with HCV/TB coinfection. Utilizing serum drug concentration monitoring to guide dosing, correction of transaminitis were achieved, which allowed the use rifamycin-containing TB therapy. These findings suggest that concomitant therapy of TB/HCV is possible, safe, and effective.