Sildenafil

(sill-DEN-ah-fil)

  Action:
Enchances the effect of nitric oxide by inhibiting phosphodiesterase type 5 in the corpus cavernosum of the penis. This results in vasodilation, increased inflow of blood into the corpora cavernosa, and ensuing penile erection upon sexual stimulation.

  Indications:
Treatment of impotence related to erectile dysfunction of the penis.

  Contraindications:
Patients using any type of organic nitrates (eg, nitroglycerin, isosorbide mono, dinitrate): Enhanced effects leading to prolonged hypotension.

  Route/Dosage:

Adults:
PO 50 mg once 0.5 to 4 hr prior to sexual activity. Titration to a 25 mg or a 100 mg dose may be used based on tolerability or efficacy. The maximum recommended use is once daily.

  Interactions:

Cimetidine, erythromycin, ketoconazole, itraconazole: Increased sildenafil levels potentially leading to increased adverse effects.

Nitratres: Hypotension (see contraindications).

  Lab Test Interferences:
None well documented.

  Adverse Reactions:

CNS:

Dizziness; headache; ataxia; hypertonia; neuralgia; neuropathy; paresthesia; tremor; vertigo; depression; insomnia; somnolence; abnormal dreams; decreased reflexes; hypesthesia; seizure; anxiety; migraine.

CV:

Angina pectoris AV block; syncope; tachycardia; palpitation; hypotension; postural hypotension; myocardial ischemia; cerebral thrombosis; cardiac arrest; heart failure; abnormal electrocardiogram; cardiomyopathy.

DERM:

Flushing; rash; urticaria; herpes simplex; pruritus; sweating; skin ulcer; contact dermatitis; exfoliative dermatitis.

EENT:

Blurred vision; sensitivity to light; nasal congestion; mydriasis; conjunctivitis; photophobia; tinnitus; eye pain; deafness; ear pain; eye hemorrhage; cataract; dry eyes; diplopia; temporary vision loss/decreased vision; ocular redness or bloodshot appearance; ocular burning; ocular swelling/pressure; increased intraocular pressure; retinal vascular disease or bleeding; vitreous detachment; traction and paramacular edema.

GI:

Dyspepsia; diarrhea; vomiting; glossitis; colitis; dysphagia; gastritis; gastroenteritis; esophagitis; stomatitis; dry mouth; abnormal LFTs; rectal hemorrhage; gingivitis.

GU:

Urinary tract infection; cystitis; nocturia; urinary frequency; breast enlargement; urinary incontinence; abnormal ejaculation; genital edema and anorgasmia; prolonged erection; priaprism; hematuria.

HEMA:

Anemia; leukopenia.

RESP:

Asthma; dyspnea; laryngitis; pharyngitis; sinusitis; bronchitis; increased sputum; increased cough.

OTHER:

Arthralgia; back pain; flu syndrome; mild and normally transient color tinge; respiratory tract infection; arthritis; arthrosis; myalgia; tendon rupture; tenosynovitis; bone pain; myasthenia; synovitis; face edema; photosensitivity reaction; shock; asthenia; pain; chills; accidental fall; abdominal pain; allergic reaction; chest pain; accidental injury; thirst; edema; gout; unstable diabetes; hyperglycemia; peripheral edema; hyperuricemia; hypoglycemic reaction; hypernatremia.

  Precautions:

Pregnancy: Category B.

Lactation: Undetermined.

Elderly: Consider an initial dose of 25 mg.

Children: Not indicated for use in children.

Cardiac risk: Exertion from renewed sexual activity may pose a risk of cardiac events such as myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, and hypertension.

Renal function impairment: Consider an initial dose of 25 mg.

Hepatic function impairment: Consider an initial dose of 25 mg.

Anatomical deformation: Use with caution in patients with anatomical deformation of the penis (eg, Peyronie's disease) or patients prone to priapism (eg, patients with sickle cell disease).

  Administration/Storage:

• Use 0.5 to 4 hr before sexual activity. Not to exceed 1 dose daily.
• Store at room temperature.

  Assessment/Interventions:

• Obtain patient history, including drug history, especially use of organic nitrates, and any known allergies.
• Assess cardiac status of the patient before initiating treatment.

  Patient/Family Education:

• Provide patient information pamphlet.
• Discuss with patients the potential cardiac risk of sexual activity in patients with preexisting cardiovascular risk factors. Advise patients who experience symptoms (eg, angina pectoris, dizziness, nausea) upon initiation of sexual activity to refrain from further activity and discuss the episode with their health care provider.
• Discuss contraindications for use with patient, especially concurrent use of organic nitrates.
• Explain that drug offers no protection against STDs.
• Counsel patient about protective measures necessary to guard against STDs, especially HIV.
• Advise patient that drug has no effect in the absence of sexual stimulation.
• Advise patient to seek immediate medical assistance in the event of an erection that persists > 4 hr.

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