Finasteride

Usage

• Medical Conditions: Finasteride is primarily prescribed for two conditions in men:

  • Benign Prostatic Hyperplasia (BPH): Also known as an enlarged prostate, BPH causes urinary problems such as difficulty urinating, weak stream, and frequent nighttime urination. Finasteride helps shrink the prostate and alleviate these symptoms.
  • Androgenetic Alopecia: This is the most common type of hair loss in men, characterized by a receding hairline and thinning hair on the crown. Finasteride helps slow down hair loss and may even promote some hair regrowth. It is not FDA approved to treat receding hairlines in women.

• Pharmacological Classification: 5-alpha reductase inhibitor.

• Mechanism of Action: Finasteride inhibits the enzyme type II 5-alpha reductase, which converts testosterone to dihydrotestosterone (DHT). DHT is a hormone responsible for prostate growth and plays a role in male pattern baldness. By reducing DHT levels, finasteride helps shrink the prostate and slow down hair loss.

Alternate Names

• International/Regional Variations: No significant variations in the generic name.

• Brand Names: Proscar (5mg, for BPH), Propecia (1mg, for hair loss).

How It Works

• Pharmacodynamics: Finasteride selectively inhibits type II 5-alpha reductase, leading to a decrease in DHT levels in the scalp and prostate. It has minimal effect on type I 5-alpha reductase.

• Pharmacokinetics:

  • Absorption: Well-absorbed orally.
  • Metabolism: Hepatically metabolized via CYP3A4 enzymes.
  • Elimination: Excreted primarily in the urine and to a lesser extent in feces.
  • Half-life: Approximately 5-6 hours in adults (longer in elderly patients).

• Mode of Action: Finasteride competitively binds to and inhibits type II 5-alpha reductase, preventing the conversion of testosterone to DHT. This reduces the stimulation of androgen receptors in the prostate and hair follicles.

• Receptor Binding/Enzyme Inhibition: Type II 5-alpha reductase inhibition.

• Elimination Pathways: Hepatic metabolism, renal and fecal excretion.

Dosage

Standard Dosage

Adults:

• BPH: 5mg orally once daily.
• Androgenetic Alopecia: 1mg orally once daily.

Children: Not indicated for use in children.

Special Cases:

• Elderly Patients: No dosage adjustment is generally required, but monitoring is recommended.
• Patients with Renal Impairment: No dosage adjustment is necessary for non-dialyzed patients.
• Patients with Hepatic Dysfunction: Use with caution. Dosage adjustment may be necessary.
• Patients with Comorbid Conditions: Use with caution in patients with liver disease.

Clinical Use Cases

Finasteride is not indicated for use in the clinical settings listed (Intubation, Surgical Procedures, Mechanical Ventilation, Intensive Care Unit (ICU) Use, and Emergency Situations).

Dosage Adjustments

Dose adjustments may be necessary in patients with hepatic impairment.

Side Effects

Common Side Effects:

• BPH: Decreased libido, erectile dysfunction, ejaculatory dysfunction, gynecomastia (breast enlargement or tenderness).
• Hair Loss: Decreased libido, erectile dysfunction, ejaculatory dysfunction.

Rare but Serious Side Effects:

• Allergic reactions (rash, itching, swelling, severe dizziness, difficulty breathing).
• Breast changes (lumps, pain, nipple discharge).
• Depression, suicidal ideation.

Long-Term Effects:

Some sexual side effects may persist even after discontinuation of the drug.

Adverse Drug Reactions (ADR):

See “Rare but Serious Side Effects”.

Contraindications

• Hypersensitivity to finasteride.
• Pregnancy (women should not handle crushed or broken tablets).
• Use in women (especially those who are or may become pregnant).

Drug Interactions

• No clinically significant drug interactions have been identified. Finasteride is not known to interact with the CYP450 system to any significant extent.

Pregnancy and Breastfeeding

• Pregnancy Safety Category: X (Contraindicated).
• Fetal Risks: Finasteride can cause abnormalities of the external genitalia in male fetuses.
• Breastfeeding: Not indicated for use in breastfeeding women. It is unknown if finasteride is excreted in human milk.

Drug Profile Summary

• Mechanism of Action: Inhibits type II 5-alpha reductase, decreasing DHT levels.
• Side Effects: Decreased libido, erectile dysfunction, ejaculatory dysfunction, gynecomastia.
• Contraindications: Hypersensitivity, pregnancy, use in women.
• Drug Interactions: No clinically significant interactions.
• Pregnancy & Breastfeeding: Contraindicated in pregnancy and breastfeeding.
• Dosage: BPH: 5mg/day, Hair loss: 1mg/day.
• Monitoring Parameters: Prostate-specific antigen (PSA) levels (for BPH), monitor for sexual side effects.

Popular Combinations

• BPH: Finasteride is sometimes combined with alpha-blockers (e.g., doxazosin) for improved symptom relief.

Precautions

• General Precautions: Monitor patients for sexual side effects, psychiatric symptoms, and breast changes.
• Specific Populations: See above sections on pregnancy, breastfeeding, and children.
• Lifestyle Considerations: Alcohol consumption may exacerbate some side effects. No specific restrictions on driving or operating machinery are generally necessary.

FAQs (Frequently Asked Questions)

Q1: What is the recommended dosage for Finasteride?

A: 5 mg once daily for BPH; 1 mg once daily for androgenetic alopecia.

Q2: How long does it take for Finasteride to work?

A: It may take 3-6 months or longer to see noticeable improvement in hair loss or BPH symptoms.

Q3: Are the side effects of Finasteride permanent?

A: Most side effects are reversible upon discontinuation of the drug. However, some sexual side effects may persist in a small percentage of patients.

Q4: Can women take Finasteride?

A: Finasteride is contraindicated in women, particularly pregnant women, due to the risk of fetal harm.

Q5: Does Finasteride prevent prostate cancer?

A: Finasteride may reduce the risk of developing some types of prostate cancer, but it may also increase the risk of developing high-grade prostate cancer. Regular PSA testing is still important.

Q6: What should I do if I miss a dose of Finasteride?

A: Skip the missed dose and take the next dose as scheduled. Do not double the dose.

Q7: Can Finasteride be used with other medications?

A: Generally, yes. No significant drug interactions have been identified.

Q8: Does Finasteride interact with food?

A: No, finasteride can be taken with or without food.

Q9: What is post-finasteride syndrome?

A: A constellation of persistent sexual, neurological, and physical symptoms reported by some men after discontinuing finasteride. This is a controversial topic and more research is needed.

Q10: Should women handle crushed or broken finasteride tablets?

A: No, women who are or may become pregnant should not handle crushed or broken finasteride tablets due to the risk of absorption and potential harm to a male fetus.