CARVEDILOL

CARVEDILOL (car-ve-di'lol) Coreg, Kredex  Classifications: alpha- and beta-adrenergic antagonist; antihypertensive; Therapeutic: antihypertensive; adrenergic blocking agent Prototype: Propanolol HCl Pregnancy Category: C

Availability

3.125 mg, 6.25 mg, 12.5 mg, 25 mg tablets

Action

Adrenergic receptor blocking agent that combines selective alpha activity and nonselective beta-adrenergic blocking actions. Both activities contribute to blood pressure reduction. Peripheral vasodilatation and, therefore, decreased peripheral resistance results from alpha₁-blocking activity of Coreg. It is 3–5 times more potent than labetalol in lowering blood pressure.

Therapeutic Effect

An effective antihypertensive agent reducing BP to normotensive range and useful in managing some angina, dysrhythmias, and CHF by decreasing myocardial oxygen demand and lowering cardiac work load.

Uses

Management of essential hypertension, CHF, in conjunction with other heart failure medications, left ventricular dysfunction post MI.

Contraindications

Patients with class IV decompensated cardiac failure, bronchial asthma, or related bronchospastic conditions (e.g., chronic bronchitis and emphysema), pulmonary edema; second- and third-degree AV block, sick sinus syndome, cardiogenic shock or severe bradycardia; pregnancy (category C), lactation.

Cautious Use

Patients on MAOI agents, diabetes, hypoglycemia; patients at high risk for anaphylactic reaction, peripheral vascular disease, cerebrovascular insufficiencies, major depression, hepatic or renal impairment. Safety and efficacy in patients <18 y of age have not been established.

Route & Dosage

CHF Adult: PO Start with 3.125 mg b.i.d. x 2 wk, may double dose q2wk as tolerated up to 25 mg b.i.d. if <85 kg or 50 mg b.i.d. if >85 kg Hypertension Adult: PO Start with 6.25 mg b.i.d., may increase by 6.25 mg b.i.d. to max of 50 mg/d

Administration

Oral

• Give with food to slow absorption and minimize risk of orthostatic hypotension.
• Dose increments should be made at 7- to 14-d intervals.

Adverse Effects (≥1%)

Body as a Whole: Increased sweating, fatigue, chest pain, pain, arthralgia. CV: Bradycardia, hypotension, syncope, hypertension, AV block, angina. GI: Diarrhea, nausea, abdominal pain, vomiting. Respiratory: Sinusitis, bronchitis. Hematologic: Thrombocytopenia. Metabolic: Hyperglycemia, weight increase, gout. CNS: Dizziness, headache, paresthesias.

Interactions

Drug: Rifampin significantly decreases carvedilol levels; cimetidine may increase carvedilol levels; clonidine, reserpine, mao inhibitors may cause hypotension or bradycardia; carvedilol may increase digoxin levels and may enhance hypoglycemic effects of insulin and oral hypoglycemic agents, may enhance the effects of antihypertensives.

Pharmacokinetics

Absorption: Rapidly from GI tract, 25–35% reaches the systemic circulation. Peak: Antihypertensive effect 7–14 d. Distribution: >98% protein bound. Metabolism: In the liver by CYP2D6 and CYP2C9. Elimination: Primarily through feces. Half-Life: 7–10 h.

Nursing Implications

Assessment & Drug Effects

• Monitor for therapeutic effectiveness which is indicated by lessening of S&S of CHF and improved BP control.
• Lab tests: Monitor liver function tests periodically; at first sign of hepatic toxicity (see Appendix F) stop drug and notify physician.
• Monitor for worsening of symptoms in patients with PVD.
• Monitor digoxin levels with concurrent use; plasma digoxin concentration may increase.

Patient & Family Education

• Do not abruptly discontinue taking this drug.
• You may experience dizziness or faintness, as a risk of orthostatic hypotension.
• Do not engage in hazardous activities while experiencing dizziness.
• If you have diabetes, the drug may increase effects of hypoglycemic drugs and mask S&S of hypoglycemia.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug