Metoprolol
Mechanism :
Metoprolol is a beta-adrenergic receptor blocking agent.
Indication :
- Hypertension
- Cyanotic spells
Contraindications :
Metoprolol is contraindicated in sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure. It should be avoided in asthmatics.
Dosing :
Oral:
1-2 mg/kg/day orally in 2 divided doses. Max: 6 mg/kg/day.
Adverse Effect :
Bradycardia, postural hypotension, heart failure, heart block, intermittent claudication and Raynaud’s phenomenon, dizziness, confusion, mood changes, nightmares, hallucinations, paresthesia, headache, bronchospasm, wheezing, dyspnea, hypoglycemia, purpura, thrombocytopenia, nausea, dyspepsia, flatulence, heartburn, diarrhea, constipation, tiredness, rash, pruritus, xerostomia.
Interaction :
Calcium Channel Blockers: Additive effect.
Prostaglandin Synthetase Inhibiting drugs: Decrease the hypotensive effects of beta blockers.
Catecholamine-Depleting drugs such as Reserpine: Hypotension, marked bradycardia, vertigo, syncopal attacks, or orthostatic hypotension.
Haloperidol: Hypotension and cardiac arrest.
Theophylline: Clearance is reduced.
Cimetidine: Increasing blood levels.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Start with small doses and titrate in accordance with response |
| <10 | Start with small doses and titrate in accordance with response |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in GFR<10 mL/min |
| HD | Not dialysed. Dose as in GFR<10 mL/min |
| HDF/High flux | Dialysed. Dose as in GFR<10 mL/ min |
| CAV/VVHD | Probably dialysed. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
Since metoprolol is extensively metabolized by the liver, blood levels are likely to increase
substantially in patients with hepatic impairment. Metoprolol should be started at a low dose and adjusted slowly according to clinical response.