Adverse drug reactions related to drugs used in orthostatic hypotension: a prospective and systematic pharmacovigilance study in France.

The aim of the present study was to investigate and characterise adverse drug reactions (ADRs) to drugs used in France for orthostatic hypotension (OH). In this prospective and systematic study, 121 consecutive out-patients suffering from primary (Parkinson's disease, pure autonomic failure, multiple system atrophy, Lewy bodies disease) or secondary (diabetic and non-diabetic peripheral neuropathies) autonomic failure with symptomatic OH requiring pharmacological treatment with at least one drug marketed in France for OH were included together with six patients with refractory neurocardiogenic syncope. Of the patients, 85 received a monotherapy-mainly with midodrine (49.4%)-and 42 received various combinations, the association of midodrine and fludrocortisone being the most frequent (66.6%). Of all the 127 patients, 88 suffered from a total of 141 ADRs (1.60 per patient) with no statistical difference in ADR frequency between monotherapy and drug combinations (P>0.05). Among ADRs, 24 (17.0%) were considered as "serious" and 16 (11.3%) were considered as "unexpected", most of them observed with heptaminol. This study shows a high frequency of ADRs (especially serious and unexpected ADRs) with antihypotensive drugs. It strongly suggests the need for a better evaluation of the safety profile of antihypotensive drugs and improvement in summary of product characteristics.