Timing of sildenafil therapy in dialysis patients
Abstract
Sir, Dr Mohamed has described a case of hypotension in a 49‐year‐old haemodialysis (HD) patient during an inter‐dialysis day on which he took a 50 mg dose of sildenafil citrate (Viagra®) and concludes that sildenafil was the most likely cause of this event [1]. As with many spontaneously reported adverse events, it is difficult to determine causality from the description given. In this case, the patient began to ‘feel unwell, with headache, nausea, epigastric pain and flushing’ 1 h after ingestion of sildenafil. When his blood pressure was measured the next day (12 h later), it was found to be 80/50. There is no way to be sure that the change in blood pressure occurred coincidentally with the onset of his symptoms. Examination of the pharmacokinetic and haemodynamic profile of sildenafil in healthy volunteers and in haemodialysis patients does not support the association between sildenafil and hypotension in this case. In healthy volunteers, the maximum observed plasma concentrations (Cmax) of sildenafil are reached within 30–120 min (Tmax: median 60 min) of oral dosing in the fasted state and the terminal half‐life (t1/2) is 4–5 h. Single oral doses of sildenafil (100 mg) administered to healthy volunteers produced mean maximum decreases in supine blood pressure of 8.4/5.5 mmHg. The reductions in blood pressure were most notable approximately 1–2 h after dosing and were not different from placebo at 8 h. This conclusion is supported by a recent Pfizer‐sponsored study…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 16 participants or records.
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