About The Study

This study compared clindamycin-primaquine with trimethoprim-sulfamethoxazole (TMP-SMX or Septra) for treating mild and moderately severe PCP (pneumonia).

Study Approach

This was a double-blind study (neither doctors nor volunteers knew which therapy volunteers received). Participants were randomly assigned to receive one of the two treatments. Study therapy was given for up to 21 days. There were additional follow-up visits at two weeks, and one, two, three, and six months after the end of therapy.

Study population

One hundred and sixteen participants enrolled in 15 Canadian centres: 60 in the TMP-SMX arm and 56 in the clindamycin-primaquine arm. Eighty-seven participants were eligible; 42 in the TMP-SMX treatment group and 45 in the clindamycin-primaquine group. There were no notable differences between the groups at the beginning of the trial. Ninety-eight percent were male; 90% were Caucasian; the average age at enrollment was 37 years; the average weight 63 kg; and the average CD4 count was 69.


While 95% of the participants had no prior episodes of PCP, 21% had received prior PCP prophylaxis (medicine to prevent PCP). Forty-nine different grade 3 or 4 toxicities (severe side effects) were observed among 34 patients. When the toxicities were examined individually, there were no significant differences in the number of toxicities between treatment groups. There were, however, significantly fewer participants suffering any kind of severe side effects in the clindamycin-primaquine group.


Clindamycin-primaquine is at least as well-tolerated and effective as TMP-SMX for the treatment of PCP, and may be useful as initial therapy in patients with a history of hypersensitivity or adverse reactions to conventional therapy. It could also be used as salvage therapy when conventional therapy fails.