9-deoxy-9-methylene-16,16-dimethyl Prostaglandin E2 (metenprost) is a potent analog of PGE2 with an extended half-life in vivo. In combination with various other PG derivatives, metenprost results in the termination of first trimester pregnancy in monkeys. A single intramuscular injection containing 0.5 mg of metenprost and 7.5 mg of 17-phenyl trinor PGF1α is very effective in terminating early pregnancy. This PG mixture is ineffective on monkeys in their third trimester of pregnancy. Metenprost, when compared to PGE2 and PGF1α, in monkey and rat, does not result in unwanted side effects such as fever or gastrointestinal problems.
