LD50

Oral LD50 is about 418 mg/kg in ratsMSDS and there have been cases of lethality in rats receiving a single oral dose of 400 mg/kg in males and 1000 mg/kg in females.^L10565

Nonclinical toxicology

In a 24-month rat study, there were no signs of the tumorigenic potential of finasteride.^L6235 In a 19-month carcinogenicity study in CD-1 mice, high doses of finasteride, at 1824 times the human exposure (250 mg/kg/day), resulted in an increase in the incidence of testicular Leydig cell adenomas and an increase in serum LH levels.^L6235 In vitro mutagenesis assays demonstrated no evidence of mutagenicity. In an in vitro chromosome aberration assay, using Chinese hamster ovary cells, there was a slight increase in chromosome aberrations with much higher doses of finasteride.^L6235

Overdose

There were no reported significant adverse events in clinical trials of male patients receiving single oral doses of finasteride up to 400 mg and multiple doses of finasteride up to 80 mg/day for three months.^L6235 As there have been no cases of overdose or clinically significant toxicity with finasteride, there are no specific recommendations in case of an overdose.^L10565

Significant adverse events

Common reproductive adverse events seen with finasteride therapy include erectile dysfunction, ejaculatory dysfunction, and loss of libido.^A178195 These adverse events tend to disappear after discontinuation or chronic use of the drug. Only causal adverse event occurring at the male reproductive system that is caused by finasteride is decreased ejaculatory volume because of the predominant action of DHT on the prostate.^A178195

Special populations

Finasteride can be safely used in elderly patients or those with renal impairment with no specific dosing adjustment recommendations.^L10565 Finasteride is indicated for male patients only, and it is advised that exposure to finasteride is avoided in pregnant women carrying male fetuses as it may lead to abnormal development of external genitalia in male fetuses.^L6235