Section 14A. The department shall purchase and distribute to the boards of health in cities and towns penicillin and such other prophylactic drugs as the commissioner may approve for the treatment of persons recovering from rheumatic fever, and said local board of health may furnish such drugs free of cost to any such person when they are prescribed for him by his physician, provided that such person, or the person bound by law to support him, is unable to pay for such drugs.