Adverse effects of (15S)-15-methyl-prostaglandin E1 in normal and paraquat-exposed rats.

Single, daily injections of approximately 1 mg/kg of (15S)-15-methyl-PGE1 (mPGE1), a PGE1 analog, have been reported to inhibit inflammation and to prolong survival in several animal models of local and systemic inflammation. We examined the effect of this dose of mPGE1 on paraquat toxicity in rats. A significant increase in early mortality was identified in mPGE1-treated rats as early as 3 hr following injection of paraquat and appeared associated with increased respiratory effort. Rats given mPGE1 without paraquat also appeared to increase respiratory effort but did not die. Rats killed at 3 hr following injections demonstrated increased lung weights in both paraquat-injected and control animals receiving mPGE1. Although a neutrophilia was identified in these animals, no significant increase in lung lavage neutrophils or albumin was identified. These data suggest that large intermittent doses of a PGE1 analog may adversely affect the respiratory system of normal and injured animals, and will accelerate mortality following exposure to potentially lethal doses of paraquat.