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Drug Details

TENIF

• Drug Class Description
  Cardioselective b-blockers (beta- blockers) / calcium-channel blockers (class II calcium antagonists).
• Generic Name
  Atenolol, nifedipine - angina
• Presentation
  Capsules Reddish brown capsules containing atenolol and a slow release formulation of nifedipine.
• Description
  Atenolol 50 mg Nifedipine 20 mg
• Indications
  

  Management of hypertension where therapy with either a calcium channel blocker or a beta-blocking drug proves inadequate. Management of chronic stable angina pectoris where therapy with a calcium channel blocker or a beta-adrenoceptor blocking drug proves inadequate.

• Adult Dosage
  

  For administration by the oral route.

  Hypertension: One capsule daily swallowed with water. If necessary, the dosage may be increased to 1 capsule dosed every 12 hours. Patients can be transferred to the combination from other antihypertensive treatments with the exception of clonidine.

  Angina: One capsule every 12 hours swallowed with water. Where additional efficacy is necessary, prophylactic nitrate therapy or additional nifedipine may be of benefit.

• Child Dosage
  

  There is no paediatric experience with Tenif and therefore Tenif should not be used in children.

• Elderly Dosage
  

  Dosage should not exceed 1 capsule daily in hypertension or 1 capsule twice daily in angina.

  The pharmacokinetics of nifedipine are altered in the elderly so that lower maintenance doses of nifedipine may be required compared to younger patients.

• Contra Indications
  

  Tenif should not be used in patients with any of the following conditions:

  - known hypersensitivity to either active component, or any other excipient or other dihydropyridines because of the theoretical risk of cross-reactivity;

  - bradycardia;

  - cardiogenic shock;

  - hypotension;

  - metabolic acidosis;

  - severe peripheral arterial circulatory disturbances;

  - second or third degree heart block;

  - sick sinus syndrome;

  - untreated phaeochromocytoma;

  - uncontrolled heart failure;

  - women capable of childbearing or during pregnancy or during lactation;

  - patients with clinically significant aortic stenosis;

  - patients with marked renal impairment (i.e. creatinine clearance below 15 ml/min/1.73 m²; serum creatinine greater than 600 micromol/litre);

  - patients receiving calcium channel blockers with negative inotropic effects eg.

  verapamil and diltiazem; unstable angina;

  - during or within one month of a myocardial infarction.

  Tenif should not be used for the treatment of acute attacks of angina.

  The safety of Tenif in malignant hypertension has not been established.

  Tenif should not be used for secondary prevention of myocardial infarction.

  Due to the nifedipine component, Tenif should not be administered in combination with rifampicin because plasma levels of nifedipine, predictive of efficacy, may not be attained due to enzyme induction

• Special Precautions
  

  Due to its beta-blocker component, Tenif:

  • Although contraindicated in uncontrolled heart failure, may be substituted with care in patients already treated with a beta-blocking drug, and/or whose signs of heart failure have been controlled. Caution must be exercised in patients with conduction defects or whose cardiac reserve is poor, especially as nifedipine also has negative inotropic effects. However, in patients already treated with a beta-blocker and/or where signs of cardiac failure have been controlled, Tenif may be substituted with care if necessary.

  • May increase the number and duration of angina attacks in patients with Prinzmetal's angina due to unopposed alpha-receptor mediated coronary artery vasoconstriction. Atenolol is a beta₁-selective beta-blocking drug; consequently, the use of Tenif may be considered although utmost caution must be exercised.

  • Although contra-indicated in severe peripheral arterial circulatory disturbances, may also aggravate less severe peripheral arterial circulatory disturbances.

  • Due to its negative effect on conduction time, caution must be exercised if it is given to patients with first-degree heart block.

  • May modify the tachycardia of hypoglycaemia.

  • May mask the signs of thyrotoxicosis.

  • Will reduce heart rate, as a result of its pharmacological action. In the rare instances when a treated patient develops symptoms, which may be attributable to a slow heart rate, the dose may be reduced.

  • Should not be discontinued abruptly in patients suffering from ischaemic heart disease.

  • May cause a 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 (epinephrine) used to treat the allergic reactions.

  • May cause a hypersensitivity reaction including angioedema and urticaria.

  Obstructive airways disease

  Tenif contains the cardioselective beta-blocking drug atenolol. Although cardioselective (beta₁) beta-blocking drugs may have less effect on lung function than non-selective beta-blocking drugs, as with all beta-blocking drugs, these should be avoided in patients with reversible obstructive airways disease, unless there are compelling clinical reasons for their use. Where such reasons exist, Tenif may be used with caution. Occasionally, some increase in airways resistance may occur in asthmatic patients, however, and this may usually be reversed by commonly used dosage of bronchodilators such as salbutamol or isoprenaline.

  The label and patient information leaflet for this product state the following warning: “If you have ever had asthma or wheezing, you should not take this medicine unless you have discussed these symptoms with the prescribing doctor”.

  Due to its nifedipine component it should be noted that:

  • In rare cases, a transient increase in blood glucose has been observed with nifedipine in acute studies. This should be considered in patients suffering from diabetes mellitus. Nifedipine has no diabetogenic effect.

  • Ischaemic pain occurs in a small proportion of patients following introduction of nifedipine monotherapy. Although a “steal” effect has not been demonstrated, patients experiencing this effect should discontinue nifedipine therapy.

  • In single cases of in vitro fertilisation, calcium antagonists like nifedipine have been associated with reversible biochemical changes in the spermatozoa's head section that may result in impaired sperm function. In those men who are repeatedly unsuccessful in fathering a child by in vitro fertilisation and where no other explanation can be found, calcium antagonists like nifedipine should be considered as possible causes.

  Hypertensive or anginal patients with clinically significant liver disease have not been studied and no dosage adjustment is suggested from the systemic availability of the monocomponents in patients with cirrhosis. However nifedipine is metabolised primarily by the liver and therefore patients with liver dysfunction should be carefully monitored. As a precaution, it is recommended that the dose should not exceed one capsule daily.

• Interactions
  

  Tenif must not be used in conjunction with calcium channel blockers with negative inotropic effects e.g. verapamil, diltiazem since this can lead to an exaggeration of these effects particularly in patients with impaired ventricular function and/or sino-atrial or atrioventricular conduction abnormalities. This may result in severe hypotension, bradycardia and cardiac failure.

  Concomitant therapy with additional dihydropyridines e.g. nifedipine, may increase the risk of hypotension, and cardiac failure may occur in patients with latent cardiac insufficiency.

  Atenolol monotherapy:

  Digitalis glycosides, in association with beta-blocking drugs, may increase atrioventricular conduction time.

  Beta-blocking drugs may exacerbate the rebound hypertension, which can follow the withdrawal of clonidine. If the two drugs are co-administered, the beta-blocking drug should be withdrawn several days before discontinuing clonidine. If replacing clonidine by beta-blocking drug therapy, the introduction of beta-blocking drugs should be delayed for several days after clonidine administration has stopped.

  Class I anti-arrhythmic drugs (eg, disopyramide) and amiodarone may have a potentiating effect on atrial-conduction time and induce negative inotropic effect.

  Concomitant use of sympathomimetic agents, e.g. adrenaline (epinephrine), may counteract the effect of beta-blocking drugs.

  Concomitant use with insulin and oral antidiabetic drugs may lead to the intensification of the blood sugar-lowering effects of these drugs.

  Concomitant use of prostaglandin synthetase-inhibiting drugs, e.g. ibuprofen or indometacin, may decrease the hypotensive effects of beta-blocking drugs.

  Caution must be exercised when using anaesthetic agents with Tenif. The anaesthetist should be informed and the choice of anaesthetic should be the agent with as little negative inotropic activity as possible. Use of beta-blocking drugs with anaesthetic drugs may result in attenuation of the reflex tachycardia and increase the risk of hypotension. Anaesthetic agents causing myocardial depression are best avoided.

  Nifedipine monotherapy:

  The antihypertensive effect of nifedipine can be potentiated by simultaneous administration of cimetidine.

  The simultaneous administration of nifedipine and quinidine may lead to serum quinidine levels being suppressed regardless of dosage of quinidine.

  The simultaneous administration of nifedipine and digoxin may lead to reduced digoxin clearance and hence an increase in the plasma digoxin level. Patients' plasma digoxin levels should be monitored and, if necessary, the digoxin dose reduced.

  As with other dihydropyridines, nifedipine should not be taken with grapefruit juice because bioavailability is increased.

  Due to enzyme induction, rifampicin has been shown to decrease the nifedipine AUC and C_max by 95% 288 ng l/ml to 8 ng l/ml and 154 ng/ml to 7.5 ng/ml respectively. This may result in reduced efficacy, therefore co-administration of nifedipine is contraindicated.

  Nifedipine may cause falsely increased spectrophotometric values of urinary vanillylmandellic acid. However, measurement with HPLC is unaffected.

• Adverse Drug Reactions
  

  Tenif is well tolerated. In clinical studies, the undesired events reported are usually attributed to the pharmacological actions of its components.

  The following undesired events, listed by body system, have been reported:

  Tenif

  Cardiovascular: flushing, oedema

  CNS: dizziness, headache

  Gastrointestinal: gastrointestinal disturbance

  Haematological: purpura

  Reproductive: impotence

  Others: fatigue

  Atenolol monotherapy

  Cardiovascular: bradycardia, heart failure deterioration, postural hypotension which may be associated with syncope, cold extremities. In susceptible patients: precipitation of heart block, intermittent claudication, Raynaud's phenomenon.

  CNS: confusion, dizziness, headache, mood changes, nightmares, psychoses and hallucinations, sleep disturbances of the type noted with other beta-blockers.

  Gastrointestinal: dry mouth, gastrointestinal disturbances, elevations of transaminase levels have been seen infrequently, rare cases of hepatic toxicity including intrahepatic cholestasis have been reported.

  Haematological: purpura, thrombocytopenia.

  Integumentary: alopecia, dry eyes, psoriasiform skin reactions, exacerbation of psoriasis, skin rashes.

  Neurological: paraesthesia.

  Respiratory: bronchospasm may occur in patients with bronchial asthma or a history of asthmatic complaints.

  Reproductive: impotence

  Special senses: visual disturbances.

  Others: hypersensitivity reaction, including angioedema and urticaria, an increase in ANA (antinuclear antibodies) has been observed, however the clinical relevance of this is not clear. Fatigue.

  Nifedipine monotherapy

  Cardiovascular: palpitations, tachycardia, gravitational oedema, marked reduction in blood pressure in dialysis patients with malignant hypertension and hypovolaemia.

  Neurological: paraesthesia.

  Respiratory: dyspnoea.

  Gastrointestinal: gingival hyperplasia, hypersensitivity type jaundice and disturbances of liver function such as increased transaminase or intrahepatic cholestasis which regress after discontinuing therapy.

  Haematological: agranulocytosis.

  Integumentary: skin reactions such as pruritus, urticaria, photosensitive dermatitis, exanthema and exfoliative dermatitis, erythromelalgia and systemic allergic reactions.

  Musculoskeletal: myalgia, tremor (both after high doses).

  Urogenital: increased frequency of micturition, gynaecomastia (in older men on long term therapy, which usually regresses on withdrawal of therapy).

  As with other sustained release dihydropyridines, exacerbation of angina pectoris may occur rarely at the start of treatment with sustained release formulations of nifedipine. The occurrence of myocardial infarction has been described although it is not possible to distinguish such an event from the natural course of ischaemic heart disease.

  Discontinuance of Tenif should be considered if, according to clinical judgement, the well-being of the patient is adversely affected by any of the above reactions.