Family planning groups and a lawmaker accused a US drug company yesterday of profiteering on Norplant, the implantable, 5-year contraceptive. The company said its $365 product is cheaper than birth-control pills. But Rep. Ron Wyden said Norplant was developed with extensive government support and sells for $23 in some Third World countries. He said its cost to Wyeth-Ayerst laboratories may be as little as $16. About 875,000 US women have had 6 match-sized hormone-dispensing rubber capsules implanted in their upper arms since 1990. Dr. Amy Pollack of the Association of Reproductive Health Professionals said 56% of the 6 million pregnancies in the US each year are unwanted. She said 1.7 million pregnancies occur among women using contraceptives. The failure rate is less than 4 per 10,000 with Norplant compared with 3 per 100 women on the pill, she said. Dr. Marc W. Deitch, Wyeth's medical director, said the company made a risky decision to bring Norplant to market in collaboration with the nonprofit Population Council. The implant costs women 20 cents a day over its 5-year life, said Dr. Deitch. The $365 cost is significantly less than the $1481 they would pay over 5 years for birth-control pills, $762 for a diaphragm and $590 for shots of Depo Provera, he said. Male condoms cost $312 and an IUD $176. Family planning advocates challenged Dr. Deitch's math. Judith DeSarno, president of the National Family Planning and Reproductive Health Association, said federally funded clinics pay only $60 for a 5-year supply of oral contraceptives. Women also must pay doctor fees--usually from $150 to $200--for inserting Norplant and eventually removing it from their upper arms.