What are the contraindications for Proscar (finasteride)?

Contraindications for Proscar (Finasteride)

Proscar (finasteride) is absolutely contraindicated in pregnant females or females who may potentially become pregnant due to the risk of abnormal development of external genitalia in a male fetus. 1

Absolute Contraindications

1. Pregnancy or potential pregnancy

   • Finasteride can cause abnormalities of external genitalia in male fetuses
   • Pregnant women should not even handle crushed or broken finasteride tablets 1
   • In animal studies, there was a dose-dependent increase in hypospadias in male offspring 1

2. Hypersensitivity

   • Any known hypersensitivity to finasteride or any component of the medication 1

3. Females

   • Not indicated for use in females 1
   • Contraindicated due to risk to male fetus if pregnancy occurs 1

Special Populations and Precautions

1. Pediatric patients

   • Not indicated for use in pediatric patients 1

2. Prostate cancer screening considerations

   • Finasteride reduces serum PSA concentration by approximately 50% within six months 1
   • For PSA interpretation in men taking finasteride, values should be doubled for comparison with normal ranges 1
   • Any confirmed increase from lowest PSA value while on finasteride may signal prostate cancer and should be evaluated 1

3. Risk of high-grade prostate cancer

   • Men taking finasteride 5mg/day may have an increased risk of high-grade prostate cancer (Gleason score 8-10) 1
   • Studies showed finasteride 1.8% vs placebo 1.1% risk of high-grade prostate cancer 2, 1

Effects on Sexual Function

1. Semen characteristics

   • Treatment may cause a 0.6 mL (22.1%) median decrease in ejaculate volume 1
   • May reduce sperm count per ejaculate, though parameters typically remain within normal range 1
   • Changes are reversible upon discontinuation with average return to baseline of 84 weeks 1

2. Sexual adverse effects

   • Loss of libido and sexual potency are the most commonly reported adverse reactions 3
   • Sexual function disorders (decreased libido, ejaculation disorder, erectile dysfunction) occur in approximately 3.8% of patients 4
   • Sexual adverse events typically reverse on discontinuation of therapy 4, 5

Clinical Considerations Before Prescribing

1. Rule out other urological conditions

   • Other urological conditions may cause similar symptoms to BPH 1
   • Prostate cancer and BPH may coexist 1

2. Assess urinary function

   • Patients with large residual urinary volume and/or severely diminished urinary flow should be carefully monitored for obstructive uropathy 1
   • These patients may not be candidates for finasteride therapy 1

Handling Precautions

1. For women who may be pregnant
   • Should not handle crushed or broken finasteride tablets 1
   • If contact occurs with crushed or broken tablets, wash the contact area immediately with soap and water 1
   • Finasteride tablets are coated to prevent contact with active ingredient during normal handling 1

Finasteride is generally well tolerated with minimal drug interactions reported in clinical practice 3, 6. However, the contraindications, particularly regarding pregnancy and potential fetal harm, must be strictly observed to ensure patient safety.