Ivabradine: heart-rate-lowering tablet for angina and heart failure

The SmPC describes ivabradine as selectively lowering heart rate in people in sinus rhythm. It treats chronic stable angina and chronic heart failure of NYHA class II to IV.

It is not suitable for people whose heartbeat is not a regular sinus rhythm, such as established atrial fibrillation.

The leaflet and SmPC describe a starting dose of 5mg twice daily, or 2.5mg twice daily in people aged 75 or over, with a maintenance maximum of 7.5mg twice daily. Tablets are taken with meals, morning and evening.

Your resting heart rate must be at least 70 beats per minute before you start. If it falls persistently below 50 beats per minute, or you develop symptoms of a slow heart rate, the dose is reduced or the medicine stopped.

Contraindications include a resting heart rate below 70, cardiogenic shock or unstable heart failure, sick sinus syndrome, sino-atrial block, third-degree heart block, severe liver impairment, pregnancy and breastfeeding, strong CYP3A4 inhibitors such as ketoconazole, clarithromycin and ritonavir, and verapamil or diltiazem taken together with it.

Tell the prescriber about heart rhythm problems, a pacemaker and any liver disease before starting.

The characteristic effect is transient enhanced brightness in a limited area of the visual field, called phosphenes. It is reported by a minority of patients, usually settles during or after treatment, and should be mentioned to your doctor.

A slow heart rate can cause dizziness or fatigue, and atrial fibrillation was reported more often with ivabradine than control in studies, so your pulse and ECG are checked if symptoms suggest an irregular rhythm. Other reported effects are headache, blurred vision and dizziness.

Avoid grapefruit juice, which roughly doubles exposure. Use caution with moderate CYP3A4 inhibitors such as fluconazole, and note that St John's wort reduces the effect considerably. Medicines that prolong the QT interval need close cardiac monitoring.

Because several medicines are excluded outright, always show your pharmacist a full medicine list before buying anything.

Ivabradine is contraindicated in pregnancy and lactation, so speak to your doctor if you could become pregnant. Women who may conceive need to discuss reliable contraception.

Regular reviews check heart rate, rhythm and symptoms. Report suspected side effects to the MHRA Yellow Card scheme, and never change the dose yourself.

Take the tablets with your morning and evening meals so that the routine is easy to remember. Keep a note of your pulse readings if your clinic asks for them, because the dose decisions in the SmPC are tied to your resting heart rate, and tell your team if you feel unusually slow, faint or tired.

If you notice flashes or patches of brightness in your vision, make a note of when they happen and how long they last, and share this at your next review rather than waiting. If you are ever prescribed an antibiotic, an antifungal or a heart medicine, remind the prescriber that you take ivabradine, since several of these are on the interaction list.