DRUG REACTIONS Sildenafil safety concerns raised Concerns over the safety of Pfizer's sildenafil ['Viagra'] have been raised by the Public Citizen Health Research Group (HRG) and by Dr Raymond Woosley from Georgetown University, Washington DC, US, according to a report in Scrip. The HRG has filed a citizen petition with the US FDA requesting that the sildenafil data sheet should be amended to include contraindications against use in men with certain medical conditions who were excluded from clinical trials of the agent. According to the HRG, some men were excluded from clinical trials of sildenafil because they were thought to be at a higher risk for adverse effects associated with the agent. However, current labelling of sildenafil does not exclude these men from using the agent now it is on the market. In response, Pfizer says that some of the exclusions cited are standard for any clinical trial. liial exclusions Specifically, men were excluded from the clinical triais if they had any of the foiiowing conditions: BP < 90150mm Hg or> 170/100mm Hg; an active peptic ulcer; a bleeding disorder; need for anticoagulants. androgens or trazodone; need for aspirin or NSAIDs and a history of peptic ulcer disease; a history of retinitis pigmentosa; poorly controlled diabetes mellitus or diabetic retinopathy; a history of stroke. myocardial infarction or life-threatening arrhythmia in the previous 6 months; heart failure. unstable angina or ECG ischaemia. The HRG has also called for more information on the labelling of sildenafil regarding its association with vision abnormalities and a warning that the recommended daily dose of l00mg should not be exceeded. Concern over vasodilators Dr Woosley has raised concerns about the concomitant administration of antihypertensives with sildenafil as this agent can also lower BP. He is particularly concerned about the effect of vasodilators. However. Pfizer says that about 24% of men included in clinical trials of sildenafil had hypertension and most were receiving antihypertensives. They add that the data sheet of sildenafil states that: 'Analyses of safety databases showed no difference in the side-effect profile in patients taking Viagra with and without antihypertensive medication' . Dr Woosley says that Pfizer only studied the coadministration of certain antihypertensives with sildenafil. He says that the effect of other drugs including prazosin and verapamil needs to be assessed In addition, other drugs which can lower BP such as terazosin and dipyridamole also need to be looked at. Dr Woosley has also raised concerns about concomitant use of sildenafil and oral hypoglycaemic agents which are metabolised by the same enzyme and so could potentially interact. Pfizer responds to Viagra safety concerns. Scrip 2350: 24. 8 Jull998 1173-832419811147.ooo:z11$01.00" Adlalnl8l'Mtlonlll Llm1Wcl11H. All rlghta_MId 21 Inpharma- 25 Jul 1188 No. 1147

Sildenafil safety concerns raised

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DRUG REACTIONS

Sildenafil safety concerns raised

Concerns over the safety of Pfizer's sildenafil ['Viagra'] have been raised by the Public Citizen Health Research Group (HRG) and by Dr Raymond Woosley from Georgetown University, Washington DC, US, according to a report in Scrip.

The HRG has filed a citizen petition with the US FDA requesting that the sildenafil data sheet should be amended to include contraindications against use in men with certain medical conditions who were excluded from clinical trials of the agent. According to the HRG, some men were excluded from clinical trials of sildenafil because they were thought to be at a higher risk for adverse effects associated with the agent. However, current labelling of sildenafil does not exclude these men from using the agent now it is on the market. In response, Pfizer says that some of the exclusions cited are standard for any clinical trial.

liial exclusions Specifically, men were excluded from the clinical

triais if they had any of the foiiowing conditions: BP < 90150mm Hg or> 170/100mm Hg; an active peptic ulcer; a bleeding disorder; need for anticoagulants. androgens or trazodone; need for aspirin or NSAIDs and a history of peptic ulcer disease; a history of retinitis pigmentosa; poorly controlled diabetes mellitus or diabetic retinopathy; a history of stroke. myocardial infarction or life-threatening arrhythmia in the previous 6 months; heart failure. unstable angina or ECG ischaemia.

The HRG has also called for more information on the labelling of sildenafil regarding its association with vision abnormalities and a warning that the recommended daily dose of l00mg should not be exceeded.

Concern over vasodilators Dr Woosley has raised concerns about the

concomitant administration of antihypertensives with sildenafil as this agent can also lower BP. He is particularly concerned about the effect of vasodilators. However. Pfizer says that about 24% of men included in clinical trials of sildenafil had hypertension and most were receiving antihypertensives. They add that the data sheet of sildenafil states that: 'Analyses of safety databases showed no difference in the side-effect profile in patients taking Viagra with and without antihypertensive medication' .

Dr Woosley says that Pfizer only studied the coadministration of certain antihypertensives with sildenafil. He says that the effect of other drugs including prazosin and verapamil needs to be assessed In addition, other drugs which can lower BP such as terazosin and dipyridamole also need to be looked at.

Dr Woosley has also raised concerns about concomitant use of sildenafil and oral hypoglycaemic agents which are metabolised by the same enzyme and so could potentially interact. Pfizer responds to Viagra safety concerns. Scrip 2350: 24. 8 Jull998

1173-832419811147.ooo:z11$01.00" Adlalnl8l'Mtlonlll Llm1Wcl11H. All rlghta_MId

Inpharma- 25 Jul 1188 No. 1147