Drugs for BPH, RCC and Wilm's Tumor Flashcards
What is BPH?
Benign prostatic hyperplasia, a common urologic disorder in males.
Non-malignant enlargement of the prostate, which occurs naturally with age
What are the classes of drugs used to treat BPH?
α -1 adrenergic antagonists
5-α reductase inhibitors
PDE-5 inhibitors
What are examples of α -1 adrenergic antagonists (BPH)? (5)
Terazosin
Doxazosin
Tamsulosin
Alfuzosin
Silodosin
What are α -1 adrenergic antagonists?
They are all selective blockers of α -1 adrenergic
What is Prazosin?
Also, an α -blocker that is used off-label to treat BPH, current guidelines do not support this use
What kind of agonist is Prazosin?
Inverse agonist at α -1ARs
What does α(1A) target?
The prostate
What does α(1B) target?
Prostate and vascalture
What does α(1D) target?
Vascalture
What is the effect of blocking α(1A) and α(1B)?
Blocking A & B of the prostate will cause SMCs of the prostate to relax –> improving urine flow
What is the MOA of Doxazosin, Terazosin, and Alfuzosin?
Block α(1A) and α(1B), thus reducing systemic vascular resistance and BP by relaxing vascular smooth muscle cells
What is the MOA of Tamsulosin & Silodosin?
Block mainly α(1A), which means little effect on systemic vascular resistance and BP
What is the PK of α1-adrenergic antagonists? (5)
- Well-absorbed following oral administration
- Absorption of alfuzosin, tamsulosin, and silodosin is increased if taken with food
- Doxazosin, alfuzosin, tamsulosin, and silodosin are metabolized by the P450 system
- Terazosin metabolized in the liver but NOT through the CYP system
- Silodosin requires dose adjustment in Renal impairment
What other way is Silodosin metabolized?
By P-glycoprotein
When are Alfuzosin, Tamsulosin, and Silodosin given?
With or after a meal
What is the contraindication with Silodosin?
Patients with severe renal dysfunction
What are the adverse effects of α1-adrenergic antagonists? (9)
- Orthostatic hypotension
- Tachycardia
- Vertigo
- Headache
- Fatigue
- Nasal congestion
- Dizziness & Drowsiness
- Floppy iris syndrome
- Blocking αARs on the ejaculatory duct may inhibit ejaculation or cause retrograde ejaculation.
Which α1-adrenergic antagonists mainly causes floppy iris syndrome?
Tamsulosin
What is retrograde ejaculation like?
Semen enters the bladder
What are the drug interaction of α1-adrenergic antagonists?
Inducers of CYP450 reduce levels of these antagonists
Inhibitors of 3A4 and 2D6 increase the levels of alpha1 blockers
Alfuzosin –> QT prolongation (class III antiarrhythmics)
Silodosin is broken by P-glycoprotein, so P-glycoprotein inhibitors increase Silodosin’s levels
What are examples of CYP450 inducers?
Phenytoin
Phenobarbital
St. John’s wort
What is an example of a P-glycoprotein inhibitor?
Cyclosporine
What are examples of 5-α reductase inhibitors?
Finastreride and Duttasteride