[Prolonged hypotension after the first dose of atenolol (author's transl)].

A 30 year-old male patient with accelerated arterial hypertension relatively resistent to diazoxide received a single oral dose of 100 mg of atenolol, following which hypotension of more than 24 hours duration and acute renal failure ensued. These alterations were reversible and did not recur with subsequent doses of atenolol. Prior therapy with diazoxide might have potentiated the hypotensive action of atenolol. The abnormality could be due to a phenomenon of hyperreactivity to the first dose of atenolol, similar to what has been described following first doses of prazosin or labetalol. This observation suggests that atenolol therapy must be started with caution, especially in patients previously treated with diazoxide.