Hypotensive Potential of Sildenafil and Tamsulosin During Orthostasis

Tuomo Nieminen; Tiit Kööbi; Teuvo L.J. Tammela; Mika Kähönen


Clin Drug Invest. 2006;26(11):667-671. 

In This Article

Abstract and Introduction


We describe pronounced hypotension in a patient during orthostatic testing while receiving treatment with sildenafil and tamsulosin, but not with placebo. The patient was 71 years of age and had no history of orthostatic reactions. He had been diagnosed with benign prostatic hyperplasia (BPH) and glaucoma simplex (open-angle glaucoma). The only regular medication used was a combination of latanoprost and timolol one drop daily into each eye. The patient was among 16 men with BPH enrolled in a study of the haemodynamic effects of tamsulosin and sildenafil. The present patient was excluded from data analysis because of atypical reactions: he experienced a decrease in peripheral vascular resistance upon orthostasis during treatment with sildenafil and tamsulosin. This led to marked hypotension and cancellation of the tilt tests with both sildenafil alone (Riva-Rocci [RR] 75/50mm Hg) and a combination of sildenafil and tamsulosin (RR 60/45mm Hg); however, tamsulosin alone also lowered blood pressure to some extent (RR 100/80mm Hg). In conclusion, even though sildenafil and tamsulosin are considered haemodynamically safe, they may induce considerable vasodilation and, subsequently, harmful hypotension in susceptible patients.


The phosphodiesterase type 5 (PDE5) inhibitors sildenafil, vardenafil and tadalafil are widely used for the treatment of erectile disorders. PDE5 inhibitors reduce the breakdown of cyclic guanosine monophosphate, a potent vasodilator, leading to engorgement of the corpus cavernosum and improved erection. An adverse reaction of sildenafil is the lowering of systolic arterial pressure (SAP) by 5–10mm Hg and diastolic arterial pressure (DAP) by approximately 7mm Hg.[1] The incidence of orthostatic hypotension during sildenafil treatment is reported to be the same as with placebo.[2]

PDE5 inhibitors are mostly used by elderly men. Some of them also have benign prostatic hyperplasia (BPH), which is often treated with α1-adrenergic receptor antagonists. These drugs, e.g. tamsulosin, relax smooth muscles in the urinary tract and the stroma of the prostate by blocking α1-adrenergic receptors. Blocking vasoconstrictive α1-adrenergic receptors in the blood vessels may cause a decrease in blood pressure, dizziness and orthostatic intolerance. However, the effect of tamsulosin 0.4mg once daily, the most typical dosage of the drug, on SAP and DAP in the supine and standing positions has been either nonsignificant or clinically irrelevant.[3] Tamsulosin has not caused orthostatic hypotension or dizziness more frequently than placebo.[3]

We describe pronounced hypotension in a patient during orthostatic testing while receiving treatment with sildenafil and tamsulosin, but not with placebo.


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