Maryland health officials have scrapped a plan to expand the number of drug treatment slots for heroin addicts because of the rising cost of methadone, the synthetic narcotic used to block the abuser's craving for the drug.

The decision not to expand methadone treatment comes at a time when state health experts are seeing an alarming increase in heroin use, up more than 50 percent since 1986, and a correlating rise in the number of addicts who have been diagnosed with AIDS.

"It's pretty cut and dry. The doubling of the cost means that money that we'd set aside will now go to pay the increased cost of medication. We won't be able to expand the number of slots," said Rick Sampson, director of the Maryland Alcohol and Drug Abuse Administration. The state also has eliminated plans to put family counselors in the public methadone maintenance clinics, he said.

While attention to drug abuse has focused in recent years on crack cocaine and its associated violence, particularly in Maryland's Washington suburbs, health officials have noticed a steady rise in heroin use -- by more than 50 percent in the state from 1986 to 1989. The state drug abuse administration projects a 10 percent increase this year alone.

There are an estimated 40,000 heroin abusers in the state, about 3,500 of whom are in public methadone treatment programs.

The increase in heroin abuse raises concerns that the state will continue to see a rise in the number of AIDS cases. Intravenous drug use, which often involves the sharing of dirty needles, is largely responsible for the spread of AIDS in the heterosexual community. Of the 122 new cases of AIDS reported in the state since January, 35 percent involve intravenous heroin or cocaine users, Sampson said.

Mallinckrodt Specialty Chemicals Co., the main U.S. producer of the synthetic narcotic, reported last summer that it would double the price of its cherry-flavored liquid methadone, trade-named Methadose, from $37 per quart to $74. Methadone is generally taken by patients either in tablet form or as a cherry-flavored liquid dissolved in fruit juice.

Mallinckrodt is estimated to supply, either directly or indirectly, 80 to 90 percent of the methadone used in U.S. drug treatment clinics each year. Nationwide, treatment administrators have accused Mallinckrodt of exploiting its dominant market position to engage in "drug-war price gouging," and federal officials warned that the price increase would result in thousands of drug abusers being denied access to treatment programs.

About 85,000 of the nation's 500,000 heroin addicts are being treated with methadone.

In Maryland, where county health departments have passed the cost of methadone treatment onto the state, the price increase means that fewer addicts will be treated, state and local health officials said.

Maryland will spend $6.4 million on methadone treatment this year. Under the cancelled expansion plan, $250,000 of new federal dollars had been slated to create 75 methadone treatment slots and to provide family counselors at existing methadone treatment programs.

In some jurisdictions there is a waiting list for methadone treatment. In Prince George's County, for example, where there are an estimated 8,000 heroin users, about 40 people are either waiting to be accepted in the program or to begin treatment at one of the county's two facilities.

"The health department is pretty much at capacity," said Anthony Stout, assistant to the county health officer.