Objectives: To evaluate the efficacy of oral calcium supplements in HIV-infected patients with nelfinavir (NFV)-associated diarrhoea, and to investigate the influence on the pharmacokinetics of nelfinavir and the active metabolite M8.
Methods: An open-label prospective trial with enrolment of 15 patients with NFV-associated diarrhoea. Study subjects received either calcium carbonate or calcium gluconate/calcium carbonate in addition to highly active antiretroviral therapy (HAART), and were randomized to (i) calcium supplements for 14 days followed by 14 without calcium supplements, or (ii) 14 days without calcium supplements followed by calcium supplements for 14 days. Clinical endpoint was the severity of diarrhoea, graded and summarized for the specific 14 day-period. In the pharmacokinetic evaluation concentrations of NFV and M8 were measured before morning dosing, and 3 h after dosing.
Results: Nine patients were treated with calcium carbonate, and six with calcium gluconate/calcium carbonate. In the paired analysis, neither of the groups had a significant improvement in diarrhoea score when treated with calcium supplements (P = 0.34 and 0.46, respectively). We found no significant differences in the concentrations of NFV and M8 between the calcium and control periods.
Conclusions: Oral calcium supplements did not significantly improve nelfinavir-associated diarrhoea. In the pharmacokinetic analysis calcium supplements did not induce major alterations in plasma concentrations of NFV and M8.