Abstract
Background and Aims
Veverimer is an investigational drug being developed as an orally administered hydrochloric acid binder for the treatment of metabolic acidosis associated with chronic kidney disease (CKD). In clinical studies, treatment with veverimer safely and effectively increased serum bicarbonate and improved objective and subjective measures of physical functioning1-3. Veverimer, a free-amine polymer, is not systemically absorbed; therefore, its potential for drug-drug interactions (DDIs) is limited to those that occur in the gastrointestinal (GI) tract (i.e., direct binding or indirect effects resulting from transient increases in gastric pH). We assessed the potential for DDIs with veverimer both in vitro and in vivo in healthy subjects.
Methods
In vitro binding to veverimer was evaluated with 16 drugs of varying molecular weight and charge. In a separate study, the effect of veverimer on gastric pH was measured continuously in vivo in healthy subjects using a microelectrode pH probe placed in the gastric compartment. Human DDI studies were conducted with 4 orally administered drugs, including those that demonstrated the most in vitro binding to veverimer and those with pH-dependent solubility (furosemide, aspirin, warfarin, dabigatran).
Results
Veverimer did not bind to any of the positively charged, neutral or zwitterionic drugs tested in vitro. It bound to 3 small (MW <332 Da), negatively charged drugs (aspirin, ethacrynic acid, furosemide); these interactions were reduced or eliminated in the presence of physiologically relevant concentrations of chloride. Neither furosemide nor aspirin showed clinically meaningful changes in pharmacokinetic parameters when coadministered with veverimer in human DDI studies (Figure 1).
Veverimer increased gastric pH by ∼3.0 and 1.5 pH units in fasted and fed subjects, respectively. The increase in gastric pH was short-lived, with a peak within 1 hour after dosing and a return to baseline after ∼1.5 hours and ∼3 hours under fasting and fed conditions, respectively. The effect of veverimer on gastric pH was similar in the presence and absence of omeprazole. No clinically meaningful changes in systemic exposure, as indicated by Cmax and AUC, were observed when 3 drugs with pH-dependent solubility were coadministered with veverimer in human DDI studies (Figure 1).
Conclusions
In human DDI studies, we observed: a) no effect of veverimer on the bioavailability of drugs with physicochemical characteristics most susceptible to direct binding to the polymer; b) small, short-lived effects of veverimer on gastric pH; and c) no effect of veverimer on the bioavailability of drugs with pH-sensitive solubility. Therefore, it is concluded that there is a negligible risk of veverimer involvement in clinically significant DDIs.
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