|Year : 2009 | Volume
| Issue : 2 | Page : 67-68
Prolonged priapism following single dose administration of sildenafil: A rare case report
Sachit Sharma1, Sabyasachi Panda1, Shilpa Sharma2, Santosh K Singh3, Amlesh Seth1, Narmada Gupta1
1 Department of Urology, All India Institute of Medical Sciences, New Delhi, India
2 Department of Paediatric Surgery, All India Institute of Medical Sciences, New Delhi, India
3 Department of Urology, PGIMS, Rohtak, Haryana, India
|Date of Submission||06-Apr-2009|
|Date of Acceptance||23-Apr-2009|
|Date of Web Publication||26-Sep-2009|
Department of Urology, All India Institute of Medical Sciences, New Delhi - 110 029
| Abstract|| |
A case of priapism following the consumption of a single dose of sildenafil is reported. A 25-year-old unmarried healthy man consumed non-prescribed 50 mg sildenafil purchased over the counter. He developed painful priapism 30 min after the drug intake that had lasted for 4 days (96 h) when he sought medical advice as an emergency. The corpus spongiosum and glans was soft and the corpus cavernosa was rigid. Winter's shunt was done. Fifteen milliliters of dark blood was aspirated with 16 G needle. Detumescence was achieved within 30 min. He was discharged after 12 h. On one month follow-up, he had normal morning erections.
A genetic basis with cross-reactivity of PDE-3 in addition to PDE-5 resulting in a cumulative erection effect may be possible elucidation for this unwanted side effect in rare cases. However, the number of cases reported with this side effect is still too less to draw further conclusions.
Keywords: Phosphodiesterase inhibitor, prolonged priapism, sildenafil
|How to cite this article:|
Sharma S, Panda S, Sharma S, Singh SK, Seth A, Gupta N. Prolonged priapism following single dose administration of sildenafil: A rare case report. Urol Ann 2009;1:67-8
|How to cite this URL:|
Sharma S, Panda S, Sharma S, Singh SK, Seth A, Gupta N. Prolonged priapism following single dose administration of sildenafil: A rare case report. Urol Ann [serial online] 2009 [cited 2017 Mar 25];1:67-8. Available from: http://www.urologyannals.com/text.asp?2009/1/2/67/56041
| Introduction|| |
Sildenafil was approved by the FDA in 1996. A phosphodiesterase type-5 inhibitor, it acts by potentiating nitric oxide's effect to enhance erection. It is known to be ineffective without sexual stimulation and resultant nitric oxide release. Here we report a case of prolonged priapism (of more than 96 h) with a single usual dose of the drug.
| Case Report|| |
A 25-year-old unmarried healthy man consumed a nonprescribed single dose of sildenafil (50 mg) purchased over the counter. He developed painful priapism 30 min after drug intake. He had used pornographic material for sexual stimulation. The priapism had lasted for 4 days when he sought medical advice from our Department of Urology as an emergency. He had not consulted any doctor earlier due to fear of embarrassment. There was no history of any priapism-inducing drug intake like antihypertensives or antipsychotic drugs or any other drugs that affect the metabolism of Sildenafil. There was no history suggestive of sickle cell trait, leukemia or multiple myeloma. On examination, the corpus spongiosum and glans was soft and the corpus cavernosa was rigid. Winter's shunt was done. Fifteen milliliters of dark blood was aspirated with 16 G needle. Detumescence was achieved within 30 min. He was discharged after 12 h. On one month follow-up, he had normal morning erections.
| Discussion|| |
The phosphodiesterase type 5 (PDE5) inhibitors currently in use include Sildenafil, vardenafil and tadalafil. 
Sildenafil citrate is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific PDE5. It is a white to off-white crystalline powder. In addition to the active ingredient, sildenafil citrate, each tablet contains microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose, triacetin and FD&C Blue #2 Aluminum lake. There may be a hypersensitivity to any component of the tablet. When sexual stimulation causes local release of NO, inhibition of PDE5 by sildenafil causes increased levels of cGMP in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum.
The side effects of this drug are determined by the biochemical sensitivity of the inhibitor. Sildenafil is rapidly absorbed after oral administration with absolute bioavailability of about 40%. The onset of activity of sildenafil is 14 min. The peak plasma levels are attained within 30 to 120 min (median 60 min) of oral dosing in the fasted state. It is eliminated predominantly by hepatic metabolism. The concomitant use of potent cytochrome P450 3A4 inhibitors (like erythromycin, ketoconazole and itraconazole), HIV protease inhibitors and nonspecific CYP inhibitor (cimetidine) is associated with increased plasma levels of Sildenafil. Both sildenafil and the metabolite have terminal half lives of about 4 h. sildenafil clearance is reduced in severe renal impairment or hepatic cirrhosis.
Priapism following the use of sildenafil in safe oral doses for a healthy individual has been reported earlier but very rarely; rather only two such reports have been found in a literature search. , The earlier reports of priapism following the use of sildenafil have been with self-administration of very large doses or in conditions predisposing to priapism. ,, Priapism may also follow simultaneous oral dose and intracavernous injection.  The first case report of priapism induced by oral sildenafil was due to a high dose (200 mg).  The initial treatment recommended is distal shunting. More proximal shunts have been done for failed distal shunts. 
The case reported here had priapism following a single dose of the usually prescribed dosage of 50 mg. An escalating dose starting at 12.5 mg and then increasing to 25 mg and followed by the usual prescribed dose of 50 mg may help to avoid the side effects of priapism. Unauthorized over-the-counter of the drug is to be condemned.  It should only be used under professional guidance as abuse of such drug may lead to severe morbidity.  Recently, an accidental consumption of six 50 mg tablets (up to 30 mg/kg) in a 19-month-old child resulting in facial flushing and priapism has been reported. 
Priapism in healthy individuals as a side effect is mentioned on the pharmaceutical literature so that a timely medical advice may be sought. Physicians should warn patients that in case of prolonged erections lasting more than 4 h, the patient should seek urgent or emergency medical assistance. If priapism is not treated immediately, permanent loss of potency may result.
Ironically, sildenafil has also been found beneficial in the treatment of priapism. Recent studies of PDE5 regulation in the penis have suggested alternative roles for the enzyme and new therapeutic opportunities involving its molecular interactions. In particular, PDE5 function is altered under derangements of androgen deficiency, decreased NO bioactivity and oxidative stress-associated inflammatory changes, thus contributing to an assortment of erectile disorders including hypogonadism-associated ED, recurrent ischemic priapism, penile vasculopathy and penile fibrosis.  Phosphodiesterase type 5 dysregulation exerts a pathogenic role for priapism associated with hematologic dyscrasias, as well as idiopathic priapism. Sildenafil has been reported to restore sexual activity in low-flow priapism, recurrent priapism, corporal fibrosis associated with recalcitrant priapism and as a preventative strategy for priapism. ,,, Sildenafil has also been used to relieve priapism in patients with sickle cell disease. 
| Conclusion|| |
It is difficult to predict which individuals are more prone to develop priapism though a genetic basis with cross-reactivity of PDE-3 in addition to PDE-5 resulting in a cumulative erection effect may be possible elucidation. However, the number of cases reported with this side effect is still too less to draw further conclusions and more molecular research needs to be done to find out the pathogenetic basis of priapism as a side effect of Sildenafil.
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