Alarmed by a rapid increase in spending on compounded drugs, like a $1,600 baby balm, insurers and others are acting to control their use.

Drug compounding involves a pharmacist making medicines for a patient who cannot be helped by mass-manufactured drugs. Compounded drugs do not require FDA approval, though Congress recently has moved to enact regulatory legislation. They might be used when a patients is allergic to an ingredient in a commercial product, or a patient needs a liquid formulation of a medication rather than it being in pill form.

Pharmacy benefit managers say there is scant evidence that these combinations of ingredients are safe or any more effective than conventional drugs. Express Scripts, the largest PMB, has said it will stop paying for more than 1,000 ingredients used in compounding, cutting spending by its health plan clients on such medicines by 95 percent. It said such spending had grown to $171 million in the first quarter of this year from $28 million in the first quarter of 2012.