Page 178 - Basic _ Clinical Pharmacology ( PDFDrive )

164 SECTION II Autonomic Drugs

TABLE 10–2 Properties of several beta-receptor–blocking drugs.

Partial Agonist Local Anesthetic Elimination Approximate
Drugs Selectivity Activity Action Lipid Solubility Half-life Bioavailability
Acebutolol β 1 Yes Yes Low 3–4 hours 50
Atenolol β 1 No No Low 6–9 hours 40
Betaxolol β 1 No Slight Low 14–22 hours 90
Bisoprolol β 1 No No Low 9–12 hours 80
Carteolol None Yes No Low 6 hours 85
Carvedilol 1 None No No Moderate 7–10 hours 25–35
Celiprolol β 1 Yes No Low 4–5 hours 70
Esmolol β 1 No No Low 10 minutes 0
Labetalol 1 None Yes Yes Low 5 hours 30
Metoprolol β 1 No Yes Moderate 3–4 hours 50
Nadolol None No No Low 14–24 hours 33
Nebivolol β 1 ? 2 No Low 11–30 hours 12–96
Penbutolol None Yes No High 5 hours >90
Pindolol None Yes Yes Moderate 3–4 hours 90
Propranolol None No Yes High 3.5–6 hours 30 3
Sotalol None No No Low 12 hours 90
Timolol None No No Moderate 4–5 hours 50
1
Carvedilol and labetalol also cause α 1 -adrenoceptor blockade.
2 β 3 agonist.
3
Bioavailability is dose-dependent.
patients with chronic obstructive pulmonary disease (COPD) humor production. (See Clinical Pharmacology and Box: The
may tolerate β -selective blockers, and the benefits, for example in Treatment of Glaucoma.)
1
patients with concomitant ischemic heart disease, may outweigh
the risks. D. Metabolic and Endocrine Effects
Beta-receptor antagonists such as propranolol inhibit sympathetic
C. Effects on the Eye nervous system stimulation of lipolysis. The effects on carbohy-
Beta-blocking agents reduce intraocular pressure, especially in drate metabolism are less clear, although glycogenolysis in the
glaucoma. The mechanism usually reported is decreased aqueous human liver is at least partially inhibited after β -receptor blockade.
2

Propranolol
0.5 mg/kg
1 µg/kg Epinephrine 1 µg/kg Epinephrine
Cardiac
contractile
force
200
Arterial
pressure 100
(mm Hg) 2
0 1 Aortic flow
(L/min)
200 0
Heart rate 1 min
(beats/min)
100

FIGURE 10–6 The effect in an anesthetized dog of the injection of epinephrine before and after propranolol. In the presence of a
β-receptor–blocking agent, epinephrine no longer augments the force of contraction (measured by a strain gauge attached to the ventricular
wall) nor increases cardiac rate. Blood pressure is still elevated by epinephrine because vasoconstriction is not blocked. (Reproduced, with permis-
sion, from Shanks RG: The pharmacology of β sympathetic blockade. Am J Cardiol 1966;18:312. Copyright Elsevier.)