Drug distributor U.S. Bioservices Corp., which is trying to get a foothold in the narrow but lucrative specialty pharmaceutical market, acquired a San Bruno, Calif., firm that consults drugmakers on reimbursements for expensive chronic-disease treatments.

Privately held U.S. Bioservices, based in the District, purchased Documedics for an undisclosed sum, both companies said. Documedics, a private firm, operates a telephone consulting center for pharmaceutical companies, answering questions from patients about third-party reimbursements for their treatment.

The acquisition of Documedics will position U.S. Bioservices to both distribute and consult for large drugmakers in the specialty-drug market. The company already sells drug regimens to patients with illnesses such as AIDS, hemophilia and multiple sclerosis

Last month, U.S. Bioservices bought Pharm Plus Resources Inc., a smaller competitor in Southern California. U.S. Bioservices has raised about $60 million to make the acquisitions, and chief executive Ethan Leder said more may come this year.

The combined revenue of the three units is expected to be $130 million in 2002, Leder said. The company now has about 350 employees, and no layoffs are expected. Roberta L. Buell, president of Documedics, said she will retain her title.

"Reimbursements are strategic," Leder said. "If these drugmakers don't get them, they are in trouble."

U.S. Bioservices is trying to increase its presence in patient-rich California. Its acquisition of Pharm Plus, for example, gave it access to the managed-care plans in the state to which Pharm Plus belonged, allowing U.S. Bioservices to work with a new client base, Leder said.