A Maryland Senate panel has advanced a measure designed to overhaul the state’s medical marijuana law and make the program more workable.

The Senate Judicial Proceedings Committee voted Tuesday to endorse a measure sponsored by Sen. Jamie B. Raskin (D-Montgomery) that would revise the law passed last year by making changes in how certifying doctors would be able to prescribe medical marijuana for patients.

The bill is similar to a measure that passed the House of Delegates, but it also differs now in several respects after the Senate panel amended it. Among the changes is a provision that would lift the cap on the number of approved growers in the state.

The House bill set the limit of licensed growers at 10, but Sen. Brian E. Frosh (D-Montgomery), who is chair of the Judicial Proceedings Committee, said the panel was concerned that such a small number could create an “oligopoly.”

Maryland legalized medical use of marijuana last year, but limited distribution to a small number of approved “academic medical centers.” None of those centers — including the University of Maryland Medical System and Johns Hopkins University — was willing to participate, however.