Hospitalization due to adverse drug reactions and drug interactions before and after HAART

found between phase 1 and 2, respectively. The mean number of medications taken (5.52 versus 5.94) and the rates of hospitalization with ADRs (20.4% versus 21.4%) or interactions (2.5% versus 2.16%) were similar between the two phases. Antiretrovirals were more common in ADR admissions post-HAART (21.3% versus 36.2%), while antiparasitics, psychotherapeutics and antineoplastics were more common pre-HAART. Other classes of drugs involved in both phases were sulphonamides, narcotics, ganciclovir, foscarnet, antimycobacterials and antifungals. ADR causality was possible or probable in more than 80% of cases. Over 60% of ADRs were grades 3 to 4, and about 85% were either the main or contributing reason for admission. About 65% of patients had at least partial recovery at the time of discharge. In phases 1 and 2, 8.9% and 2.9% of admissions,respectively, with ADRs were fatal. CONCLUSIONS: Although hospitalizations with ADRs and interactions were similar in both phases, HAART therapy has had a significant impact on the incidence and nature of ADRs at St Michael’s Hospital, Wellesley Central Site, Toronto, Ontario.