Stopping this drug should be done slowly to decrease the risk of further health problems. Pregnancy and breastfeeding
Risk for the fetus has not been ruled out, per being rated pregnancy category C in the United States. Metoprolol is category C in Australia, meaning that it may be suspected of causing harmful effects on the human fetus (but no malformations). It appears to be safe in breastfeeding. Overdose
Excessive doses of metoprolol can cause severe hypotension, bradycardia, metabolic acidosis, seizures, and cardiorespiratory arrest. Blood or plasma concentrations may be measured to confirm a diagnosis of overdose or poisoning in hospitalized patients or to assist in a medicolegal death investigation. Plasma levels are usually less than 200 μg/L during therapeutic administration, but can range from 1–20 mg/L in overdose victims. Pharmacology
General pharmacological principles of metoprolol:
beta-1 selective
moderately lipophilic
without intrinsic sympathomimetic activity
with weak membrane stabilizing activity
decreases heart rate, contractility, and cardiac output, therefore decreasing blood pressure

Mechanism of action
Metoprolol blocks β1 adrenergic receptors in heart muscle cells, thereby decreasing the slope of phase 4 in the nodal action potential (reducing Na+ uptake) and prolonging repolarization of phase 3 (slowing down K+ release). It also suppresses the norepinephrine-induced increase in the sarcoplasmic reticulum (SR) Ca2+ leak and the spontaneous SR Ca2+ release, which are the major triggers for atrial fibrillation. Pharmacokinetics
It undergoes α-hydroxylation and O-demethylation as a substrate of the cytochrome liver enzymes CYP2D6. Chemistry
The active substance metoprolol is employed either as metoprolol succinate or as metoprolol tartrate (where 100 mg metoprolol tartrate corresponds to 95 mg metoprolol succinate).
Glomeruloid hemangioma is a distinctive vascular tumor first described in 1990 when found to be associated with POEMS syndrome and Castleman disease. : 595

See also
List of cutaneous conditions


== References ==