Urology Drugs Flashcards
Name three alpha-blockers?
- Tamsulosin
- Doxazosin
- Alfuzosin
What are the common indications for use of alpha-blockers
- Benign Prostatic Hyperplasia (BPH) - as a first-line treatment
- Resistant hypertension - as an add on treatment
If the BPH isn’t controlled well enough by alpha-blockers,w which other drugs can be added?
5 alpha-reductase inhibitors
At what point might surgery be considered in men with BPH?
If there is evidence of urinary tract damage, e.g. hydronephrosis
What is the mechanism of action of alpha-blockers?
Although often described as a-blockers, most drugs in this class including doxazosin, tamulosin and alfuzosin, are highly selective for the alpha1-adrenoceptor. Alpha1-adrenoceptors are found mainly in smooth muscles, including blood vessels and the urinary tract (the bladder neck and prostate in particular). Stimulation induces contraction; blockage induces relaxation. Alpha1-blockers therefore cause vasodilation and a fall in blood pressure, and reduced resistance to bladder outflow.
What are the side effects associated with alpha-blocker use? (3)
- Postural hypotension
- Dizziness
- Syncope
- this is particularly prominent after the first dose, and due to their effects on vascular tone
What is the warning associated with alpha-blockers?
Alpha-blockers should not be used in patients with postural hypotension
What are the drug interactions associated with alpha-blocker use?
As alpha-blockers, particularly on the first dose, can cause profound hypotension, it may be prudent to omit doses of other hypotensive medications to begin with, even if the desired effect of the medication is to reduce blood pressure.
Why is it important when alpha-blockers are prescribed, particularly on the first dose, that beta-blockers are omitted?
As beta-blockers inhibit the reflex tachycardia that forms part of the compensatory response to vasodilation.
Which alpha-blocker is licensed for both BPH and hypertension? (and is therefore useful if a man has both conditions)
Doxazosin
Name a 5-alpha reductase inhibitor?
Finasteride
What are the indications for use of finasteride?
- Benign prostatic hyperplasia (BPH)
2. Androgenetic alopecia in men
What is the mechanism of action of finasteride in treating BPH?
Finasteride is based on its preferential inhibition of Type II 5a-reductase through the formation of a stable complex with the enzyme. Inhibition of Type II 5a-reductase blocks the peripheral conversion of testosterone to DHT, resulting in significant decreases in serum and tissue DHT concentrations. As DHT appears to be the principal androgen responsible for stimulation of prostatic growth, a decrease in DHT concentrations will result in a decrease in prostatic volume.
What is the mechanism of action of finasteride in treating men with androgenic alopecia?
In men with androgenic alopecia, the mechanism of action has not been fully determined, but finasteride has shown to decrease scalp DHT concentrations, reduce serum DHT, increase hair regrowth, and slow hair loss.
How is finasteride excreted, and what advice surrounding this is in the BNF?
Finasteride is excreted in semen and use of a condom is recommended if sexual partner is pregnant or likely to become pregnant.
