Ivabradine

What it is

Ivabradine slows the heart by inhibiting the If current in the sinus node, the pacemaker of the heart. Lowering the rate gives the heart muscle more time to fill and lowers its oxygen demand, without affecting blood pressure or the force of contraction. Where it is sold, which uses it is licensed for depends on the national label: in Japan it is approved only for chronic heart failure with a fast resting rate, and not for stable angina.

A usual adult range, not a national label — the dose and the timing differ by country and by product.

Used for

• Angina pectoris
• Heart failure

Approved uses differ by country — some of these may be off-label or unapproved where you live.

What to know while taking it

It is taken with food, which makes absorption more predictable. Grapefruit and grapefruit juice are avoided because they raise blood levels of the drug, as do certain antifungals, macrolide antibiotics and other enzyme inhibitors. Brief flashes of increased brightness in the field of vision are a known effect of the same channels in the retina and usually settle; they matter mainly for night driving. The heart rate is expected to fall and is followed over time.

When to see a doctor

See a doctor for a resting pulse that becomes very slow, for fainting, marked dizziness or breathlessness, or for a heartbeat that turns irregular. Visual disturbance that is persistent rather than fleeting also warrants review.

Worth knowing

• Avoid grapefruit
• Can slow the heart rate
• Brief visual flickering is possible