PDE-5 Inhibitors (Sildenafil, Vardenafil, Tadalafil)
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Reproductive Pharm
- Leuprolide
- Anastrozole
- Estrogens
- Clomiphene
- Progestins
- Mifepristone
- Copper IUDs
- Danazol
- Terbutaline, Ritodrine
- Minoxidil
- Androgens (Testosterone, Methyltestosterone)
- Flutamide
- PDE-5 Inhibitors (Sildenafil, Vardenafil, Tadalafil)
- Finasteride
Summary
PDE-5 inhibitors are a group of drugs ending in the common suffix “-afil”, including Sildenafil, Vardenafil, and Tadalafil. These drugs work by inhibiting the phosphodiesterase-5 enzyme, increasing levels of cyclic GMP and causing vasodilation through nitric oxide. This vasodilation induced by PDE-5 inhibitors is useful for the treatment of erectile dysfunction and pulmonary hypertension. However, systemic vasodilation may also lead to the side effect of life-threatening hypotension, especially when taken with nitrates.
Key Points
- PDE-5 inhibitors
- Drug Names
- - “fil” suffix (Sildenafil, Vardenafil, Tadalafil)
- Mechanism
- Inhibit phosphodiesterase inhibitors-5 (PDE-5) → increased cyclic GMP
- PDE5 inhibitors reduce degradation of cGMP, which enhances vasodilation of nitric oxide (NO)
- Inhibit phosphodiesterase inhibitors-5 (PDE-5) → increased cyclic GMP
- Indications
- Erectile dysfunction
- Increase vasodilatory effects increase blood flow to penis causing erections
- Pulmonary hypertension
- Increase vasodilatory effects reduce vascular resistance in lung, improving symptoms
- Benign Prostatic Hyperplasia
- Tadalafil used in this context to improve urine output
- Erectile dysfunction
- Adverse Effects
- Causes Hypotension
- Systemic vasodilation by NO reduces systemic vascular resistance, which can cause a precipitous drop in blood pressure
- Absolute contraindication with nitrates
- Nitrates are converted into NO to function, which acts synergistically with PDE5 inhibitors to cause life-threatening hypotension
- Causes Cyanopia (blue-tinted vision)
- Causes Headache, flushing, dyspepsia also seen
- Causes Hypotension
- Drug Names