bradycardia
3 interactions related to bradycardia
metoprolol + hawthorn
Hawthorn (Crataegus) has mild vasodilatory and positive inotropic effects that can additively lower blood pressure and slow heart rate when combined with metoprolol, increasing the risk of hypotension, bradycardia, dizziness, or syncope. The interaction is pharmacodynamic, not metabolic, so spacing the doses does not prevent it.
diltiazem + grapefruit
Grapefruit juice inhibits intestinal CYP3A4 and increases diltiazem exposure (AUC) by roughly 20% in healthy volunteers, with high inter-individual variability. The increase can amplify the drug's negative chronotropic and hypotensive effects.
cbd + beta-blockers
CBD inhibits several CYP450 enzymes (notably CYP3A4, CYP2C19, CYP2C9, CYP1A2) and may modestly inhibit CYP2D6. Beta-blockers such as metoprolol, propranolol, and carvedilol are metabolized via CYP2D6 (and CYP1A2 for propranolol), so co-use can raise beta-blocker plasma levels, with additive blood-pressure lowering and bradycardia.