From the Guidelines
No, terazosin is not finasteride, as it is an alpha-adrenergic blocker, whereas finasteride is a 5-alpha-reductase inhibitor. Terazosin works by relaxing smooth muscles in the prostate and bladder neck, improving urine flow in men with benign prostatic hyperplasia (BPH), as stated in the AUA guideline on management of BPH 1. It acts quickly to relieve urinary symptoms but doesn't affect prostate size. Finasteride, on the other hand, prevents the conversion of testosterone to dihydrotestosterone (DHT), which causes prostate enlargement, and actually shrinks the prostate gland over time (usually 3-6 months) and can prevent disease progression. These medications belong to different drug classes with distinct mechanisms of action, though they are sometimes used together for enhanced BPH treatment, as discussed in the combination therapy section of the AUA guideline 1. Some key points to consider include:
- Terazosin provides rapid symptom relief, while finasteride addresses the underlying prostate enlargement.
- Common side effects also differ: terazosin may cause dizziness and orthostatic hypotension, while finasteride may cause sexual dysfunction and takes longer to show benefits.
- The combination of an alpha-adrenergic blocker and a 5 alpha-reductase inhibitor has been found to be effective in treating symptoms and preventing the progression of BPH, with the best-tested combination being doxazosin and finasteride 1.
- The safety of specific combinations other than finasteride plus doxazosin, terazosin, and alfuzosin has not been assessed, as noted in the AUA guideline 1.
From the Research
Terazosin vs Finasteride
- Terazosin is an alpha-adrenergic blocker, whereas finasteride is a 5-alpha-reductase inhibitor 2, 3, 4.
- The primary mechanism of action of terazosin is to relax the smooth muscle of the bladder neck and prostate, thereby decreasing the resistance to urine flow and improving lower urinary tract symptoms 5, 6.
- Finasteride, on the other hand, works by inhibiting the production of dihydrotestosterone (DHT) locally within the prostate gland, which reduces prostate volume and improves lower urinary tract symptoms 4.
Comparison of Efficacy
- Studies have shown that terazosin is effective in improving IPSS, Qmax, and PVR in patients with symptomatic benign prostatic hyperplasia (BPH) 2, 3.
- Finasteride has also been shown to be effective in reducing prostate volume and improving lower urinary tract symptoms, particularly in patients with large prostates 2, 4.
- However, terazosin has been found to have a faster onset of action and produce greater improvement in voiding symptoms compared to finasteride 3.
Therapeutic Uses
- Terazosin is commonly used to treat mild to moderate cases of symptomatic BPH, while finasteride is often used to treat larger prostates and may be given for at least 6 months 2, 4.
- Combination therapy of terazosin and finasteride has not been proven to be more effective than terazosin monotherapy, but may be beneficial in reducing the clinical progression of BPH 3, 4.