How do phosphodiesterase-5 enzyme inhibitors work?
Phosphodiesterase-5enzymeinhibitors are medications used to treaterectile dysfunction, enlargedprostate(benignprostatehyperplasia), andpulmonary arterial hypertension(PAH), aconditionofhigh blood pressureinthe arteries that carry deoxygenatedbloodfrom theheartto thelungs.
Phosphodiesterase-5 enzyme inhibitors work in the following ways:
- Relax the smooth muscles in thepenisand increase blood flow into thecorpuscavernosum, the erectiletissuein the penis.
- Improve blood flow in the prostate and relieveurinarysymptoms associated with an enlarged prostate.
- Relax the smooth muscles around thepulmonary动脉,导致动脉dilationand reduced pulmonaryblood pressure.
Normally, sexual stimulation causesnitrous oxideto be released into the corpus cavernosum, which increases the concentration of a signalingmoleculeknown as cyclic guanosine monophosphate (cGMP). An increase in cGMP levels leads to relaxation ofvascularsmooth muscles, dilation of blood vessels, and improved blood flow.
The phosphodiesterase-5 enzyme regulates cGMP levels by degrading them. Phosphodiesterase-5 enzyme inhibitors prevent PDE-5 from degrading cGMP, increase its concentration in the tissue, and enhance themusclerelaxation effects of nitrous oxide.
How are phosphodiesterase-5 enzyme inhibitors used?
Phosphodiesterase-5 enzyme inhibitors are administered orally as tablets or suspensions, or asintravenousinjections for the treatment of the following conditions:
FDA-approved:
- Erectiledysfunction
- Benign prostatic hyperplasiawith or without erectile dysfunction
- Pulmonary arterialhypertension, to improve exercise ability and slow down the progression ofdiseasein patients with:
- IdiopathicPAH
- Inherited PAH
- PAH caused byconnective tissuediseases
Orphan designation:
- Duchenne muscular dystrophy(an inherited muscle degeneration disorder)
What are side effects of phosphodiesterase-5 enzyme inhibitors?
Side effects of phosphodiesterase-5 enzyme inhibitors may include the following:
- Headache
- Flushing
- Rhinitis(inflammationof the鼻腔内。)
- Epistaxis(nasalbleeding)
- Nasalcongestion
- Sinuscongestion
- Sinusitis(inflammation of the sinuses)
- Nasopharyngitis (noseandthroatinflammation)
- Bronchitis(inflammation of the bronchial passage)
- Upperrespiratorytractinfection
- Oropharyngealpain(oraland throat pain)
- Cough
- Exertionaldyspnea(shortness of breath)
- Wheezing
- Dyspepsia(indigestion)
- Diarrhea
- Nausea
- Vomiting
- Gastroesophageal refluxdisease (GERD)
- Constipation
- Gastritis
- Stomachdiscomfort
- Myalgia(muscle pain)
- Arthralgia(jointpain)
- Flulikesyndrome
- Influenza
- Back pain
- Dizziness
- Insomnia
- Depression
- Amnesia(memoryloss)
- Erythema(redness of theskin)
- Skinrash
- Pruritus(itching)
- Anaphylaxis(severeallergic reaction)
- Peripheral水肿
- Hypotension(low blood pressure)
- Postural hypotension(sudden drop in blood pressure when standing up from sitting or lying down)
- Increasedcreatinephosphokinase (CPK) levels in the blood
- Hypertension (high blood pressure)
- Angina pectoris(chest pain)
- Palpitations
- Myocardial infarction(heart attack)
- Deep vein thrombosis(blood clotin thevein)
- Priapism(prolonged erection)
- Genitourinarytract infection
- Pollakiuria (frequent urination)
- Hematuria(blood inurine)
- Nephrolithiasis(kidney stone)
- Balanitis(inflammation in the head of the penis)
- Hyperglycemia/hypoglycemia(Increase/decrease inblood glucoselevels)
- Bloodvesselblock in people withsickle cell anemia
- Change in color vision
- Conjunctivalhyperemia (dilation and redness of blood vessels in theconjunctiva,membraneon the whites of the eyes, and the inner surface of eyelids)
- Visual fielddefect
- Retinalvein/arteryocclusion(block)
- Non-arteriticanteriorischemicopticneuropathy(NAION), a condition that causes loss of blood flow and damage to theoptic nerve
- Hearing loss
Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with yourdoctoror药剂师to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking yourmedicationand never change your dose or frequency without consulting your doctor.
