California pharmacists would be allowed to dispense substitute medications that are biologically similar to brand-name treatments under a bill that cleared the state Assembly on Monday.

Biological medicines, which are created from living cells rather than by mixing chemicals, have been used to treat cancer and immune-system disorders.

Those treatments are becoming a fast-growing segment of the pharmaceutical market, with manufacturers also creating medications that are similar to some biological medicines. Unlike traditional generic medications, the so-called biosimilars resemble but are not identical to the biological medication they are replicating.

Federal officials are still in the early stages of developing regulations spelling out when biosimilars can be used. Meanwhile, state legislatures around the country have been debating the issue, with at least five states enacting laws specifying when pharmacists can substitute a biosimilar medication for a brand-name treatment, according to a staff analysis of the California bill.

Under the legislation by Sen. Jerry Hill, D-San Mateo, pharmacists could substitute a potentially cheaper biosimilar medication if it has been approved by the U.S. Food and Drug Administration. The pharmacy must notify the doctor who issued the prescription and say which medication was dispensed.

Hill's SB598 passed the Assembly Monday on a 58-4 vote and returns to the Senate for a final vote.

Several large biotech companies are among the bill's supporters. Assemblyman Richard Pan, D-Sacramento, said during Monday's floor debate that the legislation "would reduce state cost and increase patient safety."

Opponents, including health plans, pharmacists and the state Board of Pharmacy, say state rules for substituting biological medications should wait until federal officials have established regulations.

"The FDA has not approved a single biosimilar for use," said Assemblywoman Bonnie Lowenthal, D-Long Beach. "Beyond that, the FDA has not developed its protocol for substituting a biosimilar for a biological. That's years away."

Those opposing the bill also have raised concerns about the requirement to notify physicians about which medication is dispensed, saying it would be a burden on pharmacists and could reduce access to those medications.