Q&A column, 12/15

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Editor: Frederick L. Kiechle, MD, PhD

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Haloperidol administration, therapeutic range

Reference ranges for transgender patients

Verifying manufacturers’ validation studies

Q. How is haloperidol usually administered in a hospital? If blood is drawn within one to two hours after a dose, should the drug’s concentration be in the therapeutic range?

A. Depending on the medical situation, haloperidol can be administered orally, intramuscularly, or intravenously in a hospital setting. Based on the drug’s pharmacokinetics, if the drug is in the water-soluble form (e.g. lactate, hydrogen chloride), intramuscularly injected haloperidol should be circulating in the bloodstream within 20 minutes (time to peak concentration). Haloperidol has a half-life of 14 to 31 hours according to Baselt,¹ so blood concentrations are not going to decline quickly once absorption and distribution are complete. However, if the haloperidol is given intramuscularly in the form of an oily depot injection (e.g. decanoate), absorption will be much slower (six days to peak concentration and a half-life of three weeks).

There is no clearly established therapeutic range for haloperidol, and published therapeutic ranges are quite broad (5–17 ng/mL).².