Inaccuracy in the doses of injectable medications dispensed from rubber-stoppered vials.

The literature of pharmacology often assumes that a full dosage is utilized when the contents of a vial have been administered by syringe. Five hundred discarded medication vials were assayed. The residues amounted to 1.98% to 8.81% of the listed dosages. An additional 0.7% to 8.66% remained in the syringes and needles used to aspirate the vials. Routine preparation techniques do not recover medication trapped on glass and rubber surfaces; losses are greatest when small diluent volumes are added to prepare intramuscular injections. The mean dose of gentamicin recovered from 80-mg ampules was 78.65 mg, and comparable vials of tobramycin yielded 76.01 mg. The discrepancy may contribute to the "increased toxicity" of gentamicin. Each year, more than $40,000,000 worth of antibiotics are lost to a biopharmaceutical dead space. Used antibiotic and controlled substance vials pose a potential threat to the environment. Although the amount of drug lost during preparation and administration may be of little therapeutic consequence, the discrepancy between intended and administered dosage is reflected in economic loss and pharmacological confusion. Pharmacological data should be adjusted for such losses. Medication wastage could be reduced by redesign of vials and alterations in practice of the administration.