This belongs to the group of medicines known as beta-blockers. Atenolol can
be used to treat high blood pressure, angina (chest pain) and irregular
heartbeat. It has varied effects in different parts of the body. High Blood
Pressure: Atenolol works by blocking the transmission of messages to the beta
receptors in the heart which slows down the activity of the heart, decreasing
blood pressure. Angina: Atenolol works by blocking the transmission of messages
to the beta receptors in the heart which slows down the activity of the heart
and reduces the hearts need for oxygen. This makes angina attacks less likely
to occur. Irregular Heartbeat: Normally the heartbeat is regulated by special
tissues which conduct electricity. Some cases of irregular heartbeat are caused
by these tissues conducting electricity too quickly. Atenolol works by reducing
over-activity in the conducting tissue.
Catecholamine-depleting drugs (eg, reserpine) may have an additive effect when given with beta-blocking agents. Patients treated with TENORMIN plus a catecholamine depletor should therefore be closely observed for evidence of hypotension and/or marked bradycardia which may produce vertigo, syncope, or postural hypotension.
Calcium channel blockers may also have an additive effect when given with TENORMIN .
Beta blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine. If the two drugs are coadministered, the beta blocker should be withdrawn several days before the gradual withdrawal of clonidine. If replacing clonidine by beta-blocker therapy, the introduction of beta blockers should be delayed for several days after clonidine administration has stopped.
Concomitant use of prostaglandin synthase inhibiting drugs, eg, indomethacin, may decrease the hypotensive effects of beta blockers.
Information on concurrent usage of atenolol and aspirin is limited. Data from several studies, ie, TIMI-II, ISIS-2, currently do not suggest any clinical interaction between aspirin and beta blockers in the acute myocardial infarction setting.
While taking beta blockers, patients with a history of anaphylactic reaction to a variety of allergens may have a more severe reaction on repeated challenge, either accidental, diagnostic or therapeutic. Such patients may be unresponsive to the usual doses of epinephrine used to treat the allergic reaction.
TENORMIN is contraindicated in sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure.
TENORMIN is contraindicated in those patients with a history of hypersensitivity to the atenolol or any of the drug productís components.