Dosing and uses of Tenoretic (atenolol/chlorthalidone)
Adult dosage forms and strengths
atenolol/chlorthalidone
tablet
- 50mg/25mg
- 100mg/25mg
Hypertension
Not indicated for initial therapy
If the fixed dose combination represents the dose appropriate to the individual patient's needs, it may be more convenient than the separate components
Initial dose: atenolol 50 mg/chlorthalidone 25 mg PO qd
Increase to atenolol 100 mg/chlorthalidone 25 mg PO qd if needed
When necessary, another antihypertensive agent may be added gradually beginning with 50 percent of the usual recommended starting dose to avoid an excessive fall in blood pressure
Renal Impairment
Use caution in dosing/titrating patients with renal dysfunction
Cumulative effects of thiazides may develop with impaired renal function
CrCl 15-35 mL/min: Maximum 50 mg PO qd
CrCl <15 mL/min: Maximum 25 mg PO qD or 50 mg PO QOd
Other Information
Combination may be substituted for the titrated individual components
Withdraw gradually over a period of about 2 weeks
May need dosage reduction for geriatric patients
Pediatric dosage forms and strengths
<18 years: Safety/efficacy not established
Tenoretic (atenolol/chlorthalidone) adverse (side) effects
No adverse effects specific to the combination have been observed; adverse effects limited to those previously reported with atenolol and chlorthalidone
Common
atenoloL
- 2/3° AV block, bradycardia, cold extremities, diarrhea, drowsiness, hypotension, leg pain, lethargy, lightheadedness, nausea, postural hypotension, unusual dreams, vertigo
chlorthalidone
- blurred vision, constipation, diarrhea, dizziness, electrolyte abnormalities, headache, hyperglycemia, hyperuricemia, hypotension, impotence, loss of appetite, muscular spasticity, nausea, paresthesia, photosensitivity, phototoxicity, restlessness, vasculitis, vomiting, xanthopsia
Frequency not defined
atenoloL
- antinuclear antibodies (ANA), catatonia, disorientation, elevated serum hepatic enzymes & bilirubin, emotional lability, fatigue, hallucinations, headache, hypotension, impaired performance on neuropsychometric tests, impotence, lupus syndrome, mental depression, nausea, Peyronie's disease, psychoses, purpura, rashes, severe CHF, short-term memory impairment, sick sinus syndrome, thrombocytopenia, visual disturbances, wheezing & dyspnea more likely if dose >100 mg qD, xerophthalmia, xerostomia
chlorthalidone
- cardiac dysrhythmia (rare), disorder of hematopoietic structure (rare), hepatotoxicity (rare), pancreatitis (rare), pulmonary edema (rare), scaling eczema (rare), stevens-Johnson syndrome (rare), systemic lupus erythematosus (rare), toxic epidermal necrolysis (rare)
Warnings
Black box warnings
Hypersensitivity to catecholamines has been observed during withdrawaL
Exacerbation of angina and, in some cases, myocardial infarction occurrence, after abrupt discontinuation
When discontinuing chronically administered beta-blockers (particularly with ischemic heart disease) gradually reduce dose over 1-2 weeks and carefully monitor
If angina markedly worsens or acute coronary insufficiency develops, reinstate beta-blocker administration promptly, at least temporarily (in addition to other measures appropriate for unstable angina)
Warn patients against interruption or discontinuation of beta-blocker without physician advice
Because coronary artery disease is common and may be unrecognized, slowly discontinue beta-blocker therapy, even in patients treated only for hypertension
Contraindications
Anuria
Cardiogenic shock
Heart block 2°/3°
Hypersensitivity to either component or sulfonamides
Overt cardiac failure
Sinus bradycardia
Untreated pheochromocytoma
Cautions
Surgery/Anesthesia: Chronically administered beta-blockers should not be routinely withdrawn prior to major surgery; however, impaired ability of the heart to respond to reflex adrenergic stimuli may augment the risks of general anesthesia and surgical procedures
Bronchospastic disease
Cerebrovascular insufficiency
CHF, beta blockade carries the potential hazard of further depressing myocardial contractility and precipitating more severe failure
DM, fluid or electrolyte imbalance, hyperuricemia or gout, hypotension, SLe
Hyperthyroidism/thyrotoxicosis, liver disease
May aggravate digitalis toxicity
Peripheral vascular disease
Renal impairment
Risk of male sexual dysfunction
Sensitivity reactions may occur with or without history of allergy or asthma
Compromised left ventricular function
Avoid abrupt withdrawaL
Patients receiving clonidine - discontinue atenolol several days prior to withdrawal of clonidine
Administration increases risk of developing Dm
Pregnancy and lactation
Pregnancy category: d
Lactation: excreted in breast milk, use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Tenoretic (atenolol/chlorthalidone)
Mechanism of action
Atenolol/chlorthalidone is a fixed-combination tablet that combines a beta adrenergic receptor blocker atenolol, and a diuretic, chlorthalidone
Atenolol: Cardioselective inhibitor of beta(1)-adrenoceptor, has no significant intrinsic sympathomimetic activity or membrane stabilizing activity in its therapeutic dosage; exhibits beta(2)-adrenoceptors inhibition and negative chronotropic effect
Chlorthalidone: Monosulfonamyl diuretic inhibits Na and Cl reabsorption in cortical-diluting segment of ascending loop of Henle
Absorption
Bioavailability: 46-60% (atenolol); 65% (chlorthalidone)
Peak Plasma Time: Atenolol 2-4 hr; chlorthalidone 1.5-6 hr
Onset: Atenolol initial response 3 hr, peak 3-14 d; chlorthalidone: 2-6 hr
Duration: Atenolol 24 hr; chlorthalidone 72 hr
Distribution
Protein Bound: Atenolol <5%; chlorthalidone 75%
Vd: Atenolol 50-75 L/kg; chlorthalidone 3-13 L/kg
Metabolism
Atenolol: Not metabolized in liver
Metabolites: No clinically active metabolites
Elimination
Half-Life: Atenolol 6-7 hr; chlorthalidone 40-89 hr
Total body clearance 53-145 mL/min (chlorthalidone)
Dialyzable: Atenolol is removed by hemodialysis; chlorthalidone is not dialyzable
Excretion
- Atenolol: Feces 50%; urine 40-50%
- Chlorthalidone: Urine 96%
