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Desyrel (Trazodone Hydrochloride) - Drug Interactions, Contraindications, Overdosage, etc

 
 



DRUG INTERACTIONS

Drug-Drug Interactions

See also PRECAUTIONS: Drug Interactions. In vitro drug metabolism studies reveal that trazodone is a substrate of the cytochrome P450 3A4 (CYP3A4) enzyme and trazodone metabolism can be inhibited by the CYP3A4 inhibitors ketoconazole, ritonavir, and indinavir. The effect of short-term administration of ritonavir (200 mg twice daily, 4 doses) on the pharmacokinetics of a single dose of trazodone (50 mg) has been studied in 10 healthy subjects. The Cmax of trazodone increased by 34%, the AUC increased 2.4-fold, the half-life increased by 2.2-fold, and the clearance decreased by 52%. Adverse effects including nausea, hypotension, and syncope were observed when ritonavir and trazodone were co-administered.

Carbamazepine induces CYP3A4. Following co-administration of carbamazepine 400 mg/day with trazodone 100 mg to 300 mg daily, carbamazepine reduced plasma concentrations of trazodone (as well as mCPP) by 76% and 60%, respectively, compared to pre-carbamazepine values.

For those patients who responded to DESYREL, one-third of the inpatients and one-half of the outpatients had a significant therapeutic response by the end of the first week of treatment. Three-fourths of all responders demonstrated a significant therapeutic effect by the end of the second week. One-fourth of responders required 2 to 4 weeks for a significant therapeutic response.

OVERDOSAGE

Animal Oral LD50

The oral LD50 of the drug is 610 mg/kg in mice, 486 mg/kg in rats, and 560 mg/kg in rabbits.

Signs and Symptoms

Death from overdose has occurred in patients ingesting DESYREL (trazodone hydrochloride) and other drugs concurrently (namely, alcohol; alcohol + chloral hydrate + diazepam; amobarbital; chlordiazepoxide; or meprobamate).

The most severe reactions reported to have occurred with overdose of DESYREL alone have been priapism, respiratory arrest, seizures, and EKG changes. The reactions reported most frequently have been drowsiness and vomiting. Overdosage may cause an increase in incidence or severity of any of the reported adverse reactions (see ADVERSE REACTIONS).

Treatment

There is no specific antidote for DESYREL. Treatment should be symptomatic and supportive in the case of hypotension or excessive sedation. Any patient suspected of having taken an overdose should have the stomach emptied by gastric lavage. Forced diuresis may be useful in facilitating elimination of the drug.

CONTRAINDICATIONS

DESYREL is contraindicated in patients hypersensitive to DESYREL.

REFERENCES

  1. Williams JBW, Ed: Diagnostic and Statistical Manual of Mental Disorders-III, American Psychiatric Association May, 1980.
  2. Lue TF, Physiology of erection and pathophysiology of impotence. In: Wash PC, Retik AB, Stamey TA, Vaughan ED, eds. Campbell’s Urology. Sixth edition. Philadelphia: W.B. Saunders; 1992: 722-725.
  3. Goldstein I, Krane RJ, Diagnosis and therapy of erectile dysfunction. In: Wash PC, Retik AB, Stamey TA, Vaughan ED, eds. Campbell’s Urology. Sixth edition. Philadelphia: W.B. Saunders; 1992: 3071-3072.
  4. Yealy DM, Hogya PT: Priapism. Emerg Med Clin North Am. 1988; 6:509-520.
  5. Banos JE, Bosch F, Farre M, Drug-induced priapism. Its aetiology, incidence and treatment. Med Toxicol Adverse Drug Exp. 1989; 4:46-58.
  6. O’Brien WM, O’Connor KP, Lynch JH. Priapism: current concepts. Ann Emerg Med. 1989: 980-983.
  7. Bardin ED, Krieger JN. Pharmacological priapism: comparison of trazodone- and papaverine-associated cases. Int Urol Nephrol. 1990; 22:147-152.

Bristol-Myers Squibb Company
Princeton, NJ 08543-4500, USA

Rev February 2009

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