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Pseudoephedrine / terfenadine Side Effects

Applies to pseudoephedrine/terfenadine: oral tablet extended release.

Cardiovascular

Terfenadine use has been shown to cause prolongation of the QT interval. Most cardiovascular events related to terfenadine occur in patients taking higher than the recommended dose of 60 mg twice daily, those with higher than normal terfenadine serum concentrations, or in patients at risk for cardiac events. Patients with liver disease are at risk due to accumulation of the drug. Other predisposing factors for cardiovascular toxicity include congenital forms of QT interval prolongation, coronary artery disease, and electrolyte disorders including hypokalemia and hypomagnesemia. Although rare, arrhythmias have been reported in patients receiving recommended doses without apparent risk factors.

Pseudoephedrine causes vasoconstriction which generally does not produce hypertension, but may be problematic for patients with preexisting hypertension. Arrhythmias may be produced in predisposed patients. Rarely, pseudoephedrine has been reported to cause coronary artery spasm and chest pain.[Ref]

Cardiovascular system adverse effects have been associated with the use of terfenadine. Reported effects include dizziness, syncopal episodes, palpitations, ventricular arrhythmias, including torsades de pointes, cardiac arrest, and cardiac death. Pseudoephedrine generally causes a significant rise in heart rate. Hypertension and arrhythmias due to pseudoephedrine may be problematic in susceptible patients.[Ref]

Nervous system

The nervous system is rarely affected by terfenadine, however headaches are reported in approximately 6% of treated patients. Terfenadine has not been shown to cause significant drowsiness, sedation, or impair psychomotor skills.

Pseudoephedrine produces nervous system stimulation, resulting in tremor, anxiety, and nervousness. Insomnia is reported in up to 30% of pseudoephedrine-treated patients. Headache may also occur in patients receiving pseudoephedrine.[Ref]

Gastrointestinal

Gastrointestinal effects of terfenadine are rare and include nausea and dry mouth. Pseudoephedrine may cause anorexia and gastric irritation in approximately 5% of patients. Dry mouth, nose, or throat may also be caused by pseudoephedrine.[Ref]

Genitourinary

A study of the effects of terfenadine on the urination of 8 healthy male volunteers and 11 males with benign prostatic hypertrophy was not able to confirm a consistent effect on voiding characteristics.[Ref]

The genitourinary system may rarely be affected by terfenadine, resulting in urinary retention. In one reported case, the affected patient was an eight-year-old female.[Ref]

Hypersensitivity

Hypersensitivity reactions to pseudoephedrine may occur. Fixed drug eruptions secondary to pseudoephedrine have been reported.[Ref]

References

1. Kessler DA, Scheman C, Nightingale SL, et al. New boxed warnings added for seldane, hismanal. FDA Med Bull. 1992;22:2-3.

2. Kemp JP. Antihistamines--is there anything safe to prescribe? Ann Allergy. 1992;69:276-80.

3. Woosley RL, Chen Y, Freiman JP, Gillis RA. Mechanism of the cardiotoxic actions of terfenadine. JAMA. 1993;269:1532-6.

4. Safety of terfenadine and astemizole. Med Lett Drugs Ther. 1992;34:9-10.

5. Mariani PJ. Pseudoephedrine-induced hypertensive emergency: treatment with labetalol. Am J Emerg Med. 1986;4:141-2.

6. Rosen RA. Angina associated with pseudoephedrine . Ann Emerg Med. 1981;10:230-1.

7. Wiener I, Tilkian AG, Palazzolo M. Coronary artery spasm and myocardial infarction in a patient with normal coronary arteries: temporal relationship to pseudoephedrine ingestion. Cathet Cardiovasc Diagn. 1990;20:51-3.

8. Gordon RD, Ballantine DM, Bachmann AW. Effects of repeated doses of pseudoephedrine on blood pressure and plasma catecholamines in normal subjects and in patients with phaeochromocytoma. Clin Exp Pharmacol Physiol. 1992;19:287-90.

9. Stroh JE, Jr Ayars GH, Bernstein IL, Kemp JP, Podleski WK, Prenner BM, Schoenwetter WF, Salzmann JK. A comparative tolerance study of terfenadine-pseudoephedrine combination tablets and pseudoephedrine tablets in patients with allergic or vasomotor rhinitis. J Int Med Res. 1988;16:420-7.

10. Dickerson J, Perrier D, Mayersohn M, Bressler R. Dose tolerance and pharmacokinetic studies of L (+) pseudoephedrine capsules in man. Eur J Clin Pharmacol. 1978;14:253-9.

11. Covington TR, eds., Lawson LC, Young LL. Handbook of Nonprescription Drugs. Washington, DC: American Pharmaceutical Association. 1993.

12. Product Information. Seldane D (pseudoephedrine-terfenadine). Hoechst Marion-Roussel Inc, Kansas City, MO.

13. Carter CA, Wojciechowski NJ, Hayes JM, Skoutakis VA, Rickman LA. Terfenadine, a nonsedating antihistamine. Drug Intell Clin Pharm. 1985;19:812-7.

14. Connell JT. Pharmacology and clinical efficacy of terfenadine, a new H1-receptor antagonist. Pharmacotherapy. 1985;5:201-8.

15. Moser L, Huther KJ, Koch-Weser J, Lundt PV. Effects of terfenadine and diphenhydramine alone or in combination with diazepam or alcohol on psychomotor performance and subjective feelings. Eur J Clin Pharmacol. 1978;14:417-23.

16. Berkowitz RB, Tinkelman DG. Evaluation of oral terfenadine for treatment of the common cold. Ann Allergy. 1991;67:593-7.

17. Lockey RF, Findley S, Mitchell DQ, Woehler T, Lieberman P, Nicodemus CF. Effects of cetirizine versus terfenadine in seasonal allergic rhinitis. Ann Allergy. 1993;70:311-5.

18. Soto J, Sacristan JA, Alsar MJ, Sainz C. Terfenadine-induced tremor . Ann Neurol. 1993;33:226.

19. Loizou LA, Hamilton JG, Tsementzis SA. Intracranial haemorrhage in association with pseudoephedrine overdose. J Neurol Neurosurg Psychiatry. 1982;45:471-2.

20. Juniper EF, White J, Dolovich J. Efficacy of continuous treatment with astemizole (Hismanal) and terfenadine (Seldane) in ragweed pollen-induced rhinoconjunctivitis. J Allergy Clin Immunol. 1988;82:670-5.

21. Spaulding HS, Sutherland RS, Sklarew PR, Punja MK, Thrasher JB, Vaughan TR, Donatucci CF. Effect of terfenadine on urination. Ann Allergy. 1994;72:441-5.

22. Seggev JS, Fink JN. Urinary retention as a result of administration of terfenadine. J Allergy Clin Immunol. 1994;93:1071-2.

23. Shelley WB, Shelley ED. Nonpigmenting fixed drug eruption as a distinctive reaction pattern: examples caused by sensitivity to pseudoephedrine hydrochloride and tetrahydrozoline. J Am Acad Dermatol. 1987;17:403-7.

24. Tomb RR, Lepoittevin JP, Espinassouze F, Heid E, Foussereau J. Systemic contact dermatitis from pseudoephedrine. Contact Dermatitis. 1991;24:86-8.

25. Camisa C. Fixed drug eruption due to pseudoephedrine. Cutis. 1988;41:339-40.

26. Quan MB, Chow WC. Nonpigmenting fixed drug eruption after pseudoephedrine. Int J Dermatol. 1996;35:367-70.

Further information

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Some side effects may not be reported. You may report them to the FDA.

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