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Tenoretic Tablet

Description:
Each tablet contains atenolol Ph Eur 100 mg and chlorthalidon Ph Eur 25 mg.


Action:
Tenoretic combines the antihypertensive activities of 2 agents, a beta blocker (atenolol) and diuretic (chlorthalidon).
Atenolol is beta 1 selective (acts preferentially on beta 1 adrenergic receptor in the heart). Selectivity decrease with increasing dose.
Atenolol is without intrinsic sympathomimetic and membrane stabilizing activities, and as with other beta blockers, has negative inotropic effect (and is therefore contraindicated in uncontrolled heart failure).
As with others beta blockers , the mode of action of atenolol in the treatment of hypertension is unclear.
Chlorthalidon is a monosulfonamyl diuretic, increases excretion of sodium and chloride. Natriuresis is accompanied by some lose of potassium. The mechanism by which chorthalidone reduces blood pressure is not fully known but may be related to the excretion and re-distribution of body sodium.




Interaction :
Combine use of beta blockers and calcium channel blockers with negative inotropic effect (such as verapamil, diltiazem) can lead to an exaggeration of these effects particulary in patients with impaired ventricular function and or sinoatrial (SA) or atrioventricular (AV) conduction abnormalities. This may results in severe hypotension , bradycardia and cardiac failure. Neither the beta blockers nor the calcium channel blocker should be administered IV within 48 hours of discontinuing the others.
Concomitant therapy with dihydropyridines such as nifedipine, may increase the risk of hypotension and cardiac failure may occur in patient with latent cardiac insufficiency.
Digitalis glycosides, in association with beta blockers may increase atrioventicular conduction time.
Beta blockers may be exacerbate the rebound hypertension which can follow the withdrawal of clonidine. If the 2 drugs are co-administerd , the beta blockers should be delayed for several days before discontinuing clonidine. If replacing clonidine by beta blockers therapy, the introducing of beta blockers should be delayed for several days after clonidine administration has stopped.
Caution must be exercised when prescribing a beta blockers with class I antiarrhytmic agent such as disopyramide.
Concomitant use of sympathomimetic agents such as adrenaline , may counteract the effect of beta blockers.
Concomitant use of prostaglandin synthetase-inhibiting drugs such as ibuprofen, indomethacin may decrease the hypotensive effect of the beta blockers.
Preparation containing lithium should not be given with diuretics because they nay reduce its renal clearance .
Caution must be exercised whwn using anaesthetic agents with tenoretic, because may results in attenuation of the reflex tachycardia and increase the risk of hypotension.



Indication :
Hypertension




Contraindication:
Known hypersentivity to either component tenoretic
Bradycardia
Cardiogenic shock
Hypotension
Metabolic acidosis
Severe peripheral arterial circulatory disturbance
2nd or 3 rd heart block
Sick sinus syndrome
Untreated phaeochromocytoma
Uncontrolled heart failure.



Precaution :
Due to its beta blocker component, tenoretic although contraindicated in uncontrolled heart failure but may be use in patients whose signs of heart failure have been controlled. Caution must be exercised in patients whose cardiac reverse is poor. It may increase the numberand duration of angina attacks in patients with Prinzmetal`s angina due to unopposed alpha receptor-mediated coronary artery vasoconstriction.
Due to its negative effect on conduction time, caution must be exercised if it is given to patients with 1st degree heart block.
Treatment should not be dicontinuied abruptly in patients suffering from ischaemic heart diseases.
Tenoretic may cause more severe reaction to a variety of allergens, when given to patients with a history of anaphylactic reaction to such allergens. Such patients may be unresponsive to the usual doses of adrenaline used to treat allergic reaction . it may also cause an increase in airway resistance in asthmatic patients. If increase airway resistance does occur, tenoretic should be discontinued and bronchodilator therapy should be administered if necessary.
Caution must be exercised in patients with severe renal failure.




Dosage and Administration :

Adult :
One tab daily. Most patient with hypertension will give a satisfactory response to single tablet daily. There is little or no further fall in blood pressure with increase dosage, but when necessary another antihypertensive drug such as vasodilator can be added.
Eldery:
Dosage requirements are often lower in this age group
Renal failure :
The dose should be reduced by decreasing the frequency of administration.



Adverse reaction:
Bradycardia, heart failure, postural hypotension, heart block.
Confusion, dizziness, headache, mood changes, sleep disturbance.
Dry mouth, gastrointestinal disturbance.
Leucopenia, purpura, thrombocytopenia.
Alopecia, dry eyes, skin rashes, psioriasis
Paresthesia
Brochospasm
Visual disturbances.