The hypertensive effects of adrenaline (
epinephrine) can be markedly increased in patients taking non-selective
beta blockers such as propranolol. A severe and potentially life-threatening hypertensive reaction and/or marked bradycardia can develop. Cardioselective
beta blockers such as
atenolol and metoprolol interact minimally. Some evidence suggests
anaphylactic shock in patients taking
beta blockers may be resistant to treatment with adrenaline (
epinephrine).
Patients taking non-selective
beta blockers such as propranolol should only be given adrenaline (
epinephrine) in very reduced dosages because of the marked bradycardia and hypertension that can occur. A less marked effect is likely with the cardioselective
beta blockers such as
atenolol and metoprolol. Local anaesthetics such as those used in dental surgery usually contain very low concentrations of adrenaline (e.g. 5 to 20 micrograms/mL, i.e. 1:200 000 to 1:50 000) and only small volumes are usually given, so that an undesirable interaction is unlikely. Acute hypertensive episodes have been controlled with
chlorpromazine or phentola- mine. Reflex bradycardia may be managed with atropine and the pre-emptive use of
glycopyrrolate has also been suggested.