Dextromethorphan

INTRODUCTION

Indications

Symptomatic relief of coughs caused by minor viral upper respiratory tract infections or inhaled irritants. Most effective for chronic nonproductive cough. A common ingredient in nonprescription cough and cold preparations.

Action

Suppresses the cough reflex by a direct effect on the cough center in the medulla. Related to opioids structurally but has no analgesic properties. Therapeutic Effects: Relief of irritating nonproductive cough.

Adverse Reactions/Side Effects

CNS: high dose—dizziness, sedation. GI: nausea.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Assess frequency and nature of cough, lung sounds (See Appendix K), and amount and type of sputum produced. Document whether this drug is effective in reducing cough.

• Assess dizziness that might affect gait, balance, and other functional activities (See Appendix C). Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and trauma.

Patient/Client-Related Instruction

• Caution patient to avoid taking more than the recommended dose or taking alcohol or other CNS depressants concurrently with this medication; fatalities have occurred.

• Instruct patient to cough effectively: sit upright and take several deep breaths before attempting to cough.

• Advise patient to minimize cough by avoiding irritants, such as cigarette smoke, fumes, and dust. Humidification of environmental air, frequent sips of water, and sugarless hard candy may also decrease the frequency of dry, irritating cough.

• Advise patient that any cough lasting more than 1 wk or accompanied by fever, chest pain, persistent headache, or skin rash warrants medical attention.

• Instruct patient or family/caregivers to report other problematic side effects such as severe or prolonged nausea or sedation.

Pharmacokinetics

Absorption: Rapidly absorbed from the GI tract. Extended-release product is slowly absorbed.

Distribution: Unknown. Probably crosses the placenta and enters breast milk.

Metabolism and Excretion: Metabolized to dextrorphan, an active metabolite. Dextromethorphan and dextrorphan are renally excreted.

Half-life: Unknown.