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Indications and Dosage
Intracavernosal
Erectile dysfunction Adult: Initially, 5 mg (if due to spinal cord injury) or 15 mg (if due to common causes), adjusted up to 60 mg according to response. Usual dosage range: 2.5-60 mg. Reduce dose if erection persists >4 hours. Parenteral Peripheral and cerebral vascular disorders, Visceral spasms Adult: 30-120 mg 3 hourly as IV inj over 1-2 minutes or as IM inj. If cardiac extrasystole occurs, may administer 2 doses 10 minutes apart.
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Incompatibility
Incompatible w/ lactated Ringer’s inj.
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Contraindications
Complete AV block, penile fibrosis, penile deformation (e.g. angulation, cavernosal fibrosis, Peyronie’s disease), penile implants, conditions predisposing to priapism (e.g. sickle cell anaemia, multiple myeloma, leukaemia).
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Special Precautions
Patient w/ glaucoma, cardiac conduction disorders or unstable CV disease, reduced GI motility. Hepatic impairment. Pregnancy and lactation. Not indicated as treatment for impotence by intracorporeal inj.
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Adverse Reactions
Significant: Priapism, penile fibrosis, arrhythmia.
Nervous: Dizziness, syncope, malaise. CV: Flushing, mild HTN, tachycardia, orthostatic hypotension. GI: Nausea, abdominal discomfort, anorexia, constipation, diarrhoea. Hepatic: Cirrhosis. Genitourinary: Loss of penile sensation, erection difficulty, penile pain and distortion. Dermatologic: Rash, diaphoresis. Others: General discomfort, inj site reaction (e.g. pain, thrombosis). Potentially Fatal: Apnoea (rapid IV inj). |
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IM/Intra-arterial/IV/Parenteral/PO: C
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Monitoring Parameters
Monitor BP and heart rate.
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Overdosage
Symptoms: Vasomotor instability, nausea, vomiting, weakness, CNS depression, dizziness, nystagmus, diplopia, diaphoresis, flushing, sinus tachycardia; priapism (intracavernosal). Management: Ensure adequate airway and support ventilation and perfusion. Monitor vital signs, blood gases, and blood chemistry. If convulsions occur, may administer diazepam, phenobarbital, or phenytoin. For refractory seizures, may administer thiopental or halothane to produce general anaesthesia and a neuromuscular blocker to cause paralysis. Treat hypotension w/ IV fluids, inotropic vasopressor (e.g. dopamine), and leg elevation. For toxic CV effects, Ca gluconate may be useful w/ monitoring of plasma Ca concentration and ECG.
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Drug Interactions
Potentiated CNS depressant effects w/ morphine. May diminish therapeutic effect of levodopa. Increased risk of dizziness and syncope w/ alprostadil and phentolamine. Increased risk of bleeding w/ anticoagulants (e.g. warfarin or heparin) after intracavernosal inj.
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Action
Description: Papaverine is a benzylisoquinoline alkaloid that inhibits phosphodiesterase, causing spasmolytic effects on smooth muscles of the coronary, cerebral, pulmonary, and peripheral arteries. It also affects GI, biliary, and ureteral smooth muscles. Additionally, it induces penile erection by arteriolar relaxation, increasing the blood flow and volume due to relaxation of the sinusoidal wall of the corpora cavernosa and subsequent compression of the venous channels between the sinusoids and the tunica albuginea.
Onset: Erection: W/in 10 min. Duration: Erection: ≥1 hr. Pharmacokinetics: Distribution: Distributed throughout the body, mainly in liver and fat deposits. Plasma protein binding: Approx 90%. Metabolism: Rapidly metabolised in the liver. Excretion: Mainly via urine, as glucuronide conjugates of phenolic metabolites. Elimination half-life: 30-120 min. |
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Chemical Structure
 Source: National Center for Biotechnology Information. PubChem Database. Papaverine, CID=4680, https://pubchem.ncbi.nlm.nih.gov/compound/Papaverine (accessed on Jan. 22, 2020) |
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Storage
Store between 20-25°C. Protect from light.
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ATC Classification
G04BE02 - papaverine ; Belongs to the class of drugs used in erectile dysfunction.
A03AD01 - papaverine ; Belongs to the class of papaverine and derivatives. Used in the treatment of functional bowel disorders. |
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References
Anon. Papaverine. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 02/05/2017. Buckingham R (ed). Papaverine. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 02/05/2017. McEvoy GK, Snow EK, Miller J et al (eds). Papaverine Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 02/05/2017. Papaverine Hydrochloride Injection, Solution (American Regent, Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 02/05/2017.
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