Pharmacodynamics<unk>  is both a non-selective β-adrenergic receptor antagonist (β1, β2) and an α-adrenergic receptor antagonist (α1). The S(–) enantiomer accounts for the beta-blocking activity whereas the S(–) and R(+) enantiomers have alpha-blocking activity. The affinity (Ki) of<unk>  for the β-adrenergic receptors is 0.32 nM for the human β1-adrenergic receptor and 0.13 to 0.40 nM for the β2-adrenergic receptor. Using rat proteins,<unk>  has shown affinity for a variety of targets including the β1-adrenergic receptor (Ki = 0.24–0.43 nM), β2-adrenergic receptor (Ki = 0.19–0.25 nM), α1-adrenergic receptor (Ki = 3.4 nM), α2-adrenergic receptor (Ki = 2,168 nM), 5-HT1A receptor (Ki = 3.4 nM), 5-HT2 receptor (Ki = 207 nM), H1 receptor (Ki = 3,034 nM), D2 receptor (Ki = 213 nM), μ-opioid receptor (Ki = 2,700 nM), veratridine site of voltage-gated sodium channels (IC50 = 1,260 nM), serotonin transporter (Ki = 528 nM), norepinephrine transporter (Ki = 2,406 nM), and dopamine transporter (Ki = 627 nM). It is an antagonist of the human 5-HT2A receptors with moderate affinity (Ki = 547 nM), although it is unclear if this is significant for its pharmacological actions given its much stronger activity at adrenergic receptors.<unk>  reversibly binds to β-adrenergic receptors on<unk> diac myocytes. Inhibition of these receptors prevents a response to the sympathetic nervous system, leading to decreased heart rate and contractility. This action is beneficial in heart failure patients where the sympathetic nervous system is activated as a compensatory mechanism.<unk>  blockade of α1-adrenergic receptors causes vasodilation of blood vessels. This inhibition leads to decreased peripheral vascular resistance and an antihypertensive effect. There is no reflex tachycardia response due to<unk>  blockade of β1-adrenergic receptors on the heart. Pharmacokinetics<unk>  is about 25% to 35% bioavailable following oral administration due to extensive first-pass metabolism. Absorption is slowed when administered with food, however, it does not show a significant difference in bioavailability. Taking<unk>  with food decreases the risk of orthostatic hypotension. The majority of<unk>  is bound to plasma proteins (98%), mainly to albumin.<unk>  is a basic, hydrophobic compound with a steady-state volume of distribution of 115 L. Plasma clearance ranges from 500 to 700 mL/min.<unk>  is lipophilic and easily crosses the blood–brain barrier in animals, and hence is not thought to be peripherally selective. The compound is metabolized by liver enzymes, CYP2D6 and CYP2C9 via aromatic ring oxidation and glucuronidation, then further conjugated by glucuronidation and sulfation. The three active metabolites exhibit only one-tenth of the vasodilating effect of the parent compound. However, the 4'-hydroxyphenyl metabolite is about 13-fold more potent in β-blockade than the parent. The mean elimination half-life of<unk>  following oral administration ranges from 7 to 10 hours. The pharmaceutical product is a mix of two enantiomorphs, R(+)-carvedilol and S(–)-carvedilol, with differing metabolic properties. R(+)-Carvedilol undergoes preferential selection for metabolism, which results in a fractional half-life of about 5 to 9 hours, compared with 7 to 11 hours for the S(-)-carvedilol fraction.
Carvedilol
Metoprolol
Digoxin
Digitoxin
Bisoprolol
Sotalol
Diltiazem
Captopril