This is a new guideline from BTS, which outlines how to safely prescribe long term macrolide therapy in respiratory conditions. It was published in April 2020.
Most of the time, long term macrolide therapy will be initiated in secondary care. However we may well be the ones actually writing the prescription, so it is worth being aware of some of the safety concerns.
New points for me were:
- The need for ECG and LFT before and during therapy.
- The potential ototoxic effects.
What should be checked before a patient starts on long term macrolide therapy?
ECG to check for QTc. If it is > 450 ms for men and > 470 ms for women, then long term macrolide therapy shouldn't be started.
LFT should be checked before it is initiated.
What medical conditions may lead you to avoid macrolide use?
Gastrointestinal conditions. As macrolides can cause adverse GI side-effects, you should weigh up the risk-benefit ratio in patients with pre-existing gastrointestinal conditions.
Macrolide use can cause an increase in risk in certain cardiac conditions. Patients with a history of any of the following should not receive macrolides without 'careful consideration and counselling of the increased risk of adverse cardiac events':
- a history of heart disease.
- previous low serum potassium measurements.
- a slow pulse rate.
- a family history of sudden death.
- a known long QTc.
Drugs causing a lengthened QTc
If a patient is taking any other drug that lengthens the QTc, then long term macrolide therapy should not be started.
What should you check during treatment with long term macrolide therapy?
- ECG - should be checked after 1 month. An ECG should also be repeated if any other drugs that affect the QTc are started or are increased in dose. If the patient develops a prolonged QTc, the macrolide should be stopped.
- LFT - should be checked after 1 month and then every 6 months for the duration of therapy.
What ototoxic effects can be seen?
Long term macrolide therapy can cause a deterioration in hearing and or balance. This is normally reversible if the macrolide is stopped. Patients with any pre-existing hearing or balance problems should be warned of this and that they should report any changes to their hearing or balance promptly.