Compazine

A 23-YEAR-OLD WOMAN, ADMITTED TO the hospital for a minor gynecologic procedure, was under general anesthesia for approximately 45 minutes. After the procedure was completed, she was brought to her room, where she became severely nauseated. Her physician ordered 10 mg of I.M. prochlorperazine (Compazine) to combat her nausea.

Shortly after the injection, she was having trouble talking--her speech was garbled and she couldn't control her tongue. Concerned, her sister ran to the nurses' station screaming, "Hurry] Please come, my sister is having a stroke]"

One of the nurses hurried to the patient's bedside. Upon quick examination, the nurse recognized that the patient was experiencing an extrapyramidal reaction to prochlorperazine, especially because the patient had begun exhibiting symptoms soon after the injection. The nurse quickly called the physician to obtain an order for an I.M. dose of 50 mg of diphenhydramine HCl (Benadryl) to counteract the reaction.

Within minutes after the nurse administered the drug, the patient regained control of her tongue. Shortly after this episode, the patient fell asleep from the sedating effects of the diphenhydramine.

What went wrong?

The patient experienced an extrapyramidal reaction--a muscle spasm of the tongue--caused by an adverse reaction to prochlorperazine. Other typical adverse extrapyramidal reactions-which often mimic Parkinson's disease or a stroke--include tremors, drooling, and muscle spasms that usually involve muscles in the shoulders, neck, or eyes.

Extrapyramidal reactions commonly affect patients who take dopamine receptor blockers, such as prochlorperazine. Diphenhydramine HCl, an anticholinergic antihistamine, was successful at blocking the extrapyramidal reaction.

These adverse reactions aren't caused by allergy or related to the dose of the dopamine blocker. Within minutes or hours, adverse reactions can surface--or, they may not develop for several days. Young patients are more often affected, but no age group is exempt.

What precautions can you take?

* Be on the lookout for this type of adverse drug reaction if your patient is taking a dopamine receptor-blocking drug. Metoclopramide (Reglan), for example, is another dopamine receptor-blocking drug that's commonly prescribed for use as an anti-emetic. Other drugs in this category include almost all antipsychotic agents, such as chlorpromazine HCl (Thorazine), haloperidol (Haldol), and fluphenazine (Prolixin).

* Teach your patient about adverse reactions she may experience from an anticholinergic drug such as diphenhydramine HCl. These reactions commonly include dry mouth, blurred vision, constipation, and urinary hesitancy or urine retention. Teach her how to manage these adverse reactions. Also, provide her with guidelines so she'll know at what point she should notify her physician about them.

This column discusses adverse drug reactions and methods of prevention. Dr. Shuster is a clinical associate professor at Temple University and a clinical pharmacist at Medical College of Pennsylvania Hospital, both in Philadelphia. Send examples of adverse drug reactions to Joel Shuster, PharmD. The Institute for Safe Medication Practices, 320 w. Street Rd., Warminster, PA 18974-3236, or fax the informatin to (215) 956-9266. If we use your item, we'll publish it anonymously and send you an honorarium of $25.

Copyright Springhouse Corporation Jan 1996
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