Sildenafil


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Erectile dysfunction 50 mg approx 1 hr before sexual intercourse. Max: 100 mg/day. Pulmonary arterial HTN 5 mg or 20 mg tid. IV Pulmonary arterial HTN 2.5 mg or 10 mg tid.
Dosage Details
Intravenous
Pulmonary arterial hypertension
Adult: 2.5 mg or 10 mg tid.

Oral
Erectile dysfunction
Adult: 50 mg approx 1 hr before sexual intercourse, may adjust depending on response. Max: 100 mg daily.

Oral
Pulmonary arterial hypertension
Adult: 5 mg or 20 mg tid.
Child: 1-17 yr ≤20 kg: 10 mg tid; >20 kg: 20 mg tid.
Special Patient Group
Patients on CYP3A4 inhibitors: Initially, not more than 25 mg daily.
Patients on ritonavir-boosted HIV inhibitors: Should not exceed 25 mg 48 hrly.
Patients stable on alpha-blockers: Initially, 25 mg.
Renal Impairment
PO
Erectile dysfunction
CrCl mL/min Dosage
<30 Initially, 25 mg.

PO
Pulmonary arterial hypertension
CrCl mL/min  Dosage
 <30  20 mg bid.

IV
Pulmonary arterial hypertension
CrCl mL/min  Dosage
 <30  10 mg bid.
Hepatic Impairment
PO
Erectile dysfunction: Mild or moderate: Initially, 25 mg. Severe: Contraindicated.
Pulmonary arterial hypertension: Mild or moderate: 20 mg bid. Severe: Contraindicated.

IV
Pulmonary arterial hypertension: Mild or moderate: 10 mg bid. Severe: Contraindicated.
Administration
May be taken with or without food.
Reconstitution
Oral susp: Add a total of 90 mL of water in 2 portions, 60 mL for the 1st addition and 30 mL for the 2nd addition, to provide a susp containing 10 mg/mL. After each addition, cap and shake the bottle vigorously for at least 30 sec.
Contraindications
Patient w/ severe CV disorders (e.g. unstable angina, cardiac failure), loss of vision in 1 eye because of non-arteritic anterior ischaemic optic neuropathy (NAION), hypotension (BP <90/50 mmHg), recent history of stroke or MI, known hereditary degenerative retinal disorders. Severe hepatic impairment. Concomitant use w/ nitrates of any form and nicorandil.
Special Precautions
Patient w/ anatomical deformation of the penis or haematological disorders that may predispose to priapism. Not indicated for pulmonary HTN secondary to sickle-cell disease. Mild to moderate hepatic and severe renal impairment. Childn (chronic use). Pregnancy and lactation.
Adverse Reactions
Headache, flushing, dyspepsia, visual disturbances (e.g. blurred vision, photophobia, chromatopsia, cyanopsia, eye irritation, eye pain and redness); dizziness, insomnia, anxiety, vertigo, epistaxis, nasal congestion, pyrexia, GI disturbances (e.g. diarrhoea, vomiting), priapism; skin rashes, erythema, alopecia, limb/back pain, myalgia, facial oedema, fluid retention, paraesthesia, UTI, dyspnoea, cough, rhinitis, sinusitis, bronchitis, cellulitis, sudden decrease or loss of hearing, anaemia, leucopenia, gynaecomastia, urinary frequency or incontinence, haematuria, seizures, cerebrovascular haemorrhage, transient ischaemic attack, palpitations, syncope, HTN, hypotension. Rarely, hypersensitivity reactions, NAION causing permanent loss of vision, retinal haemorrhage.
Potentially Fatal: Serious CV events (e.g. MI, arrhythmias, tachycardia, unstable angina). 
Patient Counseling Information
This drug may cause dizziness and altered vision, if affected, do not drive or operate machinery. Seek medical assistance in cases of prolonged erection (>4 hr) or sudden visual or hearing loss.
MonitoringParameters
Monitor BP and pulse when used concurrently w/ hypotensive drugs in the treatment of pulmonary arterial HTN.
Overdosage
Symptoms: Hypotension, syncope, prolonged erection. Management: Supportive treatment. For severe hypotension, may consider placing the patient in the Trendelenburg position, initiating fluid resuscitation, providing judicious use of an IV α-adrenergic agonist (e.g. phenylephrine), providing a combined α- and β-adrenergic agonist (norepinephrine) for BP support, and/or providing intra-aortic balloon.
Drug Interactions
Symptomatic HTN may occur when used w/ alpha-blockers. Reduced clearance w/ CYP3A4 inhibitors (e.g. cimetidine, delavirdine, erythromycin, itraconazole, ketoconazole). Increased plasma concentrations w/ HIV-protease inhibitors particularly by ritonavir-boosted regimens. Decreased plasma concentrations w/ CYP3A4 inducers (e.g. rifampicin, bosentan).
Potentially Fatal: Potentiation of hypotensive effects of nitrates of any form and nicorandil.
Food Interaction
May increase plasma levels w/ grapefruit juice.
Action
Description: Sildenafil inhibits phosphodiesterase type-5 (PDE-5) which is responsible for cyclic guanosine monophosphate (cGMP) degradation in the corpus cavernosum. Inhibition of PDE-5 increases cGMP which results in pulmonary vascular smooth muscle cells relaxation.
Onset: Approx 60 min.
Duration: 2-4 hr.
Pharmacokinetics:
Absorption: Rapidly absorbed from the GI tract. Bioavailability: Approx 40%. Time to peak plasma concentration: W/in 30-120 min.
Distribution: Widely distributed into body tissues. Plasma protein binding: Approx 96%.
Metabolism: Hepatically by CYP3A4 (major route) and CYP2C9 isoenzymes.
Excretion: Mainly via faeces (as metabolites); urine (lesser extent). Terminal half-life: Approx 4 hr.
Chemical Structure

Click on icon to see table/diagram/image
Storage
Store between 15-30°C.
ATC Classification
G04BE03 - sildenafil ; Belongs to the class of drugs used in erectile dysfunction.
Disclaimer: This information is independently developed by MIMS based on Sildenafil from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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