Metohexal (Metoprolol Tartrate)

Metoprolol is a selective β1‑adrenergic blocker used in several cardiovascular disease categories.

• Hypertension: lowers systemic blood pressure to reduce the risk of stroke and heart attack.
• Angina pectoris: decreases myocardial oxygen demand, relieving chest pain.
• Myocardial infarction: improves survival by reducing cardiac workload and preventing arrhythmias.
• Heart failure: enhances ventricular filling and reduces mortality in chronic heart failure.
• Cardiac arrhythmias: controls heart rate in supraventricular tachyarrhythmias.

• Metoprolol selectively antagonizes β1‑adrenergic receptors located primarily in cardiac tissue. By blocking catecholamine binding, it reduces cyclic AMP formation, leading to decreased heart rate, contractility, and conduction velocity. The resulting decline in myocardial oxygen consumption and peripheral resistance lowers blood pressure and alleviates ischemic stress, while also stabilising cardiac rhythm. These effects are dose‑dependent and reversible upon discontinuation, and Metoprolol’s cardio‑selectivity minimizes bronchial impact compared with non‑selective beta blockers.

Metoprolol may be associated with a range of adverse reactions, varying from mild to severe.

Common Side Effects

• Fatigue: persistent tiredness or reduced stamina that may affect daily activities.
• Dizziness: light‑headedness or vertigo, often occurring upon standing quickly.
• Bradycardia: heart rate slower than 60 beats per minute, which can cause weakness.
• Gastrointestinal upset: nausea, abdominal discomfort or loss of appetite.

Serious or Rare Side Effects

• Severe bradycardia or heart block: markedly slow heart rhythm that can lead to syncope and requires immediate medical evaluation.
• Hypotension: significant drop in blood pressure causing faintness, dizziness, or shock.
• Bronchospasm or respiratory distress: constriction of airways, particularly in patients with underlying asthma or COPD.

When prescribing Metoprolol, clinicians should observe several safety considerations to minimise risk.

• Monitor blood pressure: ensure target levels are achieved without excessive hypotension.
• Assess heart rate: watch for bradycardia, especially in patients with conduction disorders.
• Use caution in asthma: β1‑selectivity reduces but does not eliminate risk of bronchospasm.
• Avoid abrupt discontinuation: taper the dose to prevent rebound tachycardia or hypertension.
• Adjust dose in renal impairment: reduced clearance may require lower dosing.
• Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Metoprolol can interact with other medicines, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Non‑selective beta blockers: concurrent use may cause excessive β‑blockade.
• Calcium channel blockers (verapamil, diltiazem): can markedly depress cardiac conduction and contractility.
• Clonidine (abrupt withdrawal): stopping clonidine while on Metoprolol may precipitate severe hypertension.

Moderate Interactions (Monitor Closely)

• ACE inhibitors: combined effect may enhance hypotensive response.
• Diuretics: additive blood pressure lowering and electrolyte disturbances.
• NSAIDs: may reduce antihypertensive effect of Metoprolol.