Inderide Disease Interactions

The use of beta-adrenergic receptor blocking agents (aka beta-blockers) is contraindicated in patients with sinus bradyarrhythmia or heart block greater than the first degree (unless a functioning pacemaker is present). Due to their negative inotropic and chronotropic effects on the heart, the use of beta-blockers is likely to exacerbate these conditions.

The use of beta-adrenergic receptor blocking agents (aka beta-blockers) is contraindicated in patients with hypotension or cardiogenic shock. Due to their negative inotropic and chronotropic effects on the heart, the use of beta-blockers is likely to further depress cardiac output and blood pressure, which can be detrimental in these patients.

Beta-adrenergic receptor blocking agents (aka beta-blockers) in general should not be used in patients with overt congestive heart failure (CHF). Sympathetic stimulation may be important in maintaining the hemodynamic function in these patients, thus beta-blockade can worsen the heart failure. However, therapy with beta-blockers may be beneficial and can be administered cautiously in some CHF patients provided they are well compensated and receiving digitalis, diuretics, an ACE inhibitor, and/or nitrates. Carvedilol, specifically, is indicated for use with these agents in the treatment of mild to severe heart failure of ischemic or cardiomyopathic origin. There is also increasing evidence that the addition of a beta-blocker to standard therapy can improve morbidity and mortality in patients with advanced heart failure, although it is uncertain whether effectiveness varies significantly with the different agents. Data from one meta-analysis study suggest a greater reduction of mortality risk for nonselective beta-blockers than for beta-1 selective agents.

Beta-adrenergic receptor blocking agents (aka beta-blockers) may mask symptoms of hypoglycemia such as tremors, tachycardia and blood pressure changes. In addition, the nonselective beta-blockers (e.g., propranolol, pindolol, timolol) may inhibit catecholamine-mediated glycogenolysis, thereby potentiating insulin-induced hypoglycemia and delaying the recovery of normal blood glucose levels. Since cardioselectivity is not absolute, larger doses of beta-1 selective agents may demonstrate these effects as well. Therapy with beta-blockers should be administered cautiously in patients with diabetes or predisposed to spontaneous hypoglycemia.

The use of beta-adrenergic receptor blocking agents (aka beta-blockers) in patients with a history of allergic reactions or anaphylaxis may be associated with heightened reactivity to culprit allergens. The frequency and/or severity of attacks may be increased during beta-blocker therapy. In addition, these patients may be refractory to the usual doses of epinephrine used to treat acute hypersensitivity reactions and may require a beta-agonist such as isoproterenol.

Heightened sensitivity to catecholamines may occur after prolonged use of beta-adrenergic receptor blocking agents (aka beta-blockers). Exacerbation of angina, myocardial infarction and ventricular arrhythmias have been reported in patients with coronary artery disease following abrupt withdrawal of therapy. Cessation of beta-blocker therapy, whenever necessary, should occur gradually with incrementally reduced dosages over a period of 1 to 2 weeks in patients with coronary insufficiency. Patients should be advised not to discontinue treatment without first consulting with the physician. In patients who experience an exacerbation of angina following discontinuation of beta-blocker therapy, the medication should generally be reinstituted, at least temporarily, along with other clinically appropriate measures.

Due to their negative inotropic and chronotropic effects on the heart, beta-adrenergic receptor blocking agents (aka beta-blockers) reduce cardiac output and may precipitate or aggravate symptoms of arterial insufficiency in patients with peripheral vascular disease. In addition, the nonselective beta-blockers (e.g., propranolol, pindolol, timolol) may attenuate catecholamine-mediated vasodilation during exercise by blocking beta-2 receptors in peripheral vessels. Therapy with beta-blockers should be administered cautiously in patients with peripheral vascular disease. Close monitoring for progression of arterial obstruction is advised.

Some beta-adrenergic receptor blocking agents (i.e., non-cardioselective beta-blockers) are contraindicated in patients with bronchial asthma or with a history of bronchial asthma, or severe chronic obstructive pulmonary disease. In general, beta-adrenergic receptor blocking agents should not be used in patients with bronchospastic diseases. Beta blockade may adversely affect pulmonary function by counteracting the bronchodilation produced by catecholamine stimulation of beta-2 receptors. If beta-blocker therapy is necessary in these patients, an agent with beta-1 selectivity (e.g., atenolol, metoprolol, betaxolol) is considered safer, but should be used with caution nonetheless. Cardioselectivity is not absolute and can be lost with larger doses.

Propranolol is primarily metabolized by the liver. Patients with liver disease may be at greater risk for adverse effects from propranolol due to decreased drug clearance. Therapy with propranolol should be administered cautiously in patients with liver disease. Dosage adjustments may be necessary.

The use of thiazide diuretics is contraindicated in patients with anuria.

The use of thiazide diuretics is commonly associated with loss of electrolytes, most significantly potassium but also sodium, chloride, bicarbonate, and magnesium. The loss of other electrolytes such as phosphate, bromide and iodide is usually slight. Potassium and magnesium depletion may lead to cardiac arrhythmias and cardiac arrest. Other electrolyte-related complications include metabolic alkalosis and hyponatremia, which are rarely life-threatening. Therapy with thiazide diuretics should be administered cautiously in patients with or predisposed to fluid and electrolyte depletion, including patients with primary or secondary aldosteronism (may have low potassium levels); those with severe or prolonged diarrhea or vomiting; and those with poor nutritional status. Fluid and electrolyte abnormalities should be corrected prior to initiating therapy, and blood pressure as well as serum electrolyte concentrations monitored periodically and maintained at normal ranges during therapy. Patients should be advised to immediately report signs and symptoms of fluid or electrolyte imbalance, including dry mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, arrhythmia, or gastrointestinal disturbances such as nausea and vomiting. Digitalized patients and patients with a history of ventricular arrhythmias should be monitored carefully, since development of hypokalemia may be particularly dangerous in these patients. The risk of hypokalemia may be minimized by slow diuresis, a lower thiazide dosage, potassium supplementation, or combined use with a potassium-sparing diuretic.

Patients with severe liver disease or cirrhosis are very susceptible to thiazide-induced hypokalemic hypochloremic alkalosis. Blood ammonia concentrations may be further increased in patients with previously elevated concentrations. Hepatic encephalopathy and death have occurred secondary to the electrolyte alterations accompanying diuretic use. Therapy with thiazide diuretics should be administered cautiously in patients with impaired hepatic function or progressive liver disease, and discontinued promptly if signs of impending hepatic coma appear (e.g., tremors, confusion, and increased jaundice).

The use of thiazide diuretics has been reported to possibly exacerbate or activate systemic lupus erythematosus. Reported cases have generally been associated with chlorothiazide and hydrochlorothiazide. Therapy with thiazide diuretics should be administered cautiously in patients with a history or risk of SLE.

Thiazide diuretics may be ineffective when the glomerular filtration rate is low (GFR < 25 mL/min) because they are not expected to be filtered into the renal tubule, their site of action. In addition, thiazide diuretics decrease the GFR and may precipitate azotemia in renal disease. Cumulative effects may also develop because most of these drugs are excreted unchanged in the urine by glomerular filtration and active tubular secretion. Therapy with thiazide diuretics should be administered cautiously at reduced dosages in patients with renal impairment. If renal function becomes progressively worse, as indicated by rising BUN or serum creatinine levels, an interruption or discontinuation of thiazide therapy should be considered.

Beta-adrenergic blocking agents (beta-blockers), should be used with caution in patients with cerebrovascular insufficiency because of their potential effects relative to blood pressure and pulse. If signs or symptoms suggesting reduced cerebral blood flow are observed, consideration should be given to discontinuing these agents.

Systemic beta-adrenergic receptor blocking agents (aka beta-blockers) may lower intraocular pressure. Therefore, patients with glaucoma or intraocular hypertension may require adjustments in their ophthalmic regimen following a dosing change or discontinuation of beta-blocker therapy.

Beta-adrenergic receptor blocking agents (aka beta-blockers) may alter serum lipid profiles. Increases in serum VLDL and LDL cholesterol and triglycerides, as well as decreases in HDL cholesterol, have been reported with some beta-blockers. Patients with preexisting hyperlipidemia may require closer monitoring during beta-blocker therapy, and adjustments made accordingly in their lipid-lowering regimen.

When beta-adrenergic receptor blocking agents (aka beta-blockers) are used to alleviate symptoms of hyperthyroidism such as tachycardia, anxiety, tremor and heat intolerance, abrupt withdrawal can exacerbate thyrotoxicosis or precipitate a thyroid storm. To minimize this risk, cessation of beta-blocker therapy, when necessary, should occur gradually with incrementally reduced dosages over a period of 1 to 2 weeks. Patients should be advised not to discontinue treatment without first consulting with the physician. Close monitoring is recommended during and after therapy withdrawal.

During chronic administration, the clearance of beta-blockers that are primarily metabolized by the liver (e.g., labetalol, metoprolol, penbutolol, propranolol) may be increased in patients with hyperthyroidism due to increased liver blood flow and enhanced activity of drug-metabolizing enzymes. Pharmacokinetic studies have demonstrated an approximately 50% increase in systemic clearance of propranolol during long-term therapy. In general, the dosage required to achieve therapeutic blood concentrations in such patients may be higher than that required in euthyroid patients and should be individualized.

Beta-adrenergic receptor blocking agents (aka beta-blockers) may potentiate muscle weakness consistent with certain myasthenic symptoms such as diplopia, ptosis, and generalized weakness. Several beta-blockers have been associated rarely with aggravation of muscle weakness in patients with preexisting myasthenia gravis or myasthenic symptoms. Use cautiously in patients with myasthenia gravis.

Administration of beta-blockers alone in the setting of pheochromocytoma has been associated with a paradoxical increase in blood pressure due to the attenuation of beta receptor-mediated vasodilatation in skeletal muscle. In patients with pheochromocytoma, an alpha-blocking agent should be initiated prior to the use of any beta-blocking agent. Caution should be taken in the administration of these agents to patients suspected of having pheochromocytoma.

The use of beta-blockers in psoriatic patients should be carefully weighed since the use of these agents may cause an aggravation in psoriasis.

Beta-adrenergic blockade in patients with Wolff-Parkinson-White syndrome and tachycardia has been associated with severe bradycardia requiring treatment with a pacemaker. In one case, this result was reported after an initial dose of 5 mg propranolol. The use of beta-adrenergic receptor blocking agents (aka beta-blockers) should be administered cautiously in these patients.

Agents with non-selective beta-blocking activity may provoke chest pain in patients with Prinzmetal's variant angina. the use of non-selective beta blockers is not recommended in these patients. Caution should be taken in the administration of these agents to patients suspected of having Prinzmetal's variant angina.

Propranolol plasma clearance was reduced in patients with chronic renal failure. Chronic renal failure has been associated with a decrease in drug metabolism via downregulation of hepatic cytochrome P450 activity resulting in a lower "first-pass" clearance; therefore, therapy with propranolol should be administered cautiously in patients with impaired renal function. Propranolol is not significantly dialyzable.

Thiazide diuretics should be used with caution in patients with history of bronchial asthma as sensitivity reactions may occur.

Thiazide diuretics may cause hyperglycemia and glycosuria in patients with diabetes. They may also precipitate diabetes in prediabetic patients. These effects are usually reversible following discontinuation of the drugs. Therapy with thiazide diuretics should be administered cautiously in patients with diabetes mellitus, glucose intolerance, or a predisposition to hyperglycemia. Patients with diabetes mellitus should be monitored more closely during thiazide therapy, and their antidiabetic regimen adjusted accordingly.

Thiazide diuretics may increase serum triglyceride and cholesterol levels, primarily LDL and VLDL. Whether these effects are dose-related and sustained during chronic therapy are unknown. Patients with preexisting hyperlipidemia may require closer monitoring during thiazide therapy, and adjustments made accordingly in their lipid-lowering regimen

Urinary calcium excretion is decreased by thiazide diuretics during chronic administration. Pathologic changes in the parathyroid gland with hypercalcemia and hypophosphatemia have been reported during prolonged therapy. However, the common complications of hyperparathyroidism such as renal lithiasis, bone resorption, and peptic ulceration have not been seen. Clinicians should be cognizant of these effects when prescribing or administering thiazide therapy to patients with hyperparathyroidism. These drugs should be discontinued before carrying out tests for parathyroid function.

Thiazide diuretics decrease the rate of uric acid excretion. Hyperuricemia occurs frequently but is usually asymptomatic and rarely leads to clinical gout except in patients with a history of gout or chronic renal failure. Therapy with thiazide diuretics should be administered cautiously in such patients.

Thiazide diuretics may decrease serum PBI (protein-bound iodine) levels without associated thyroid disturbance. Clinicians should be cognizant of this effect when prescribing or administering thiazide therapy to patients with thyroid disorders.