Long-term nitrofurantoin: an analysis of complication awareness, monitoring, and pulmonary injury cases

Dear Sir
We note with interest the research undertaken by Speirs et al identifying a lack of awareness amongst prescribers of serious adverse effects that can occur with long-term nitrofurantoin and the need for more robust monitoring guidelines. As a result of discussions on the potential safety risk of long-term nitrofurantoin and known medico-legal implications,(1,2) we examined the monitoring schedule for nitrofurantoin across a convenience sample of ten practices in two of our primary care networks.

The computer records of patients that had a record of being prescribed nitrofurantoin (15 or more tablets) were searched over one month in early 2021. From a total registered population of approximately 86,000 patients, we identified 41 patients (35 female) who had received a prescription for prophylactic nitrofurantoin. Thirty-two (78%) of this cohort were aged over 65 years.

In only 8 (20%) instances was there any evidence in the GP records of a discussion with the patient about possible adverse effects. Liver function had been monitored in 22 (54%) patients within 6 months, whilst a respiratory review had occurred for only 5 (12%) patients, though such a review had been triggered by suspicion of a newly presenting pulmonary complication.

Nitrofurantoin is commonly used for the treatment and prophylaxis of recurrent urinary tract infections (UTIs), and typically any such prescription is commenced by a GP, though such a decision may also be made following advice from a urology specialist. Standard prescribing advice is that at commencement of prophylaxis there should be discussion with the patient of the risks of long-term antibiotics including resistance and possible adverse effects, and monitoring (liver function and for signs of pulmonary adverse effects, especially in the elderly) is advised for long-term therapy.(3) Our small study, albeit with no follow up of patient outcomes, points to some deficiencies in following this advice.

We echo the call by Speirs et al for augmentation of current guidelines with a model monitoring plan.

Yours sincerely

Will Howe, GP, Lostwithiel Surgery, Cornwall
Ronan Sheehan, Clinical Pharmacist, Three Harbours and Bosvena Health PCN, Cornwall
Marco Motta, Pharmacist, NHS Kernow CCG Medicines Optimisation Team, Cornwall
Mike Wilcock, Pharmacist, Royal Cornwall Hospitals NHS Trust, Cornwall

References
1. https://www.medicalprotection.org/uk/articles/complications-of-nitrofura...
2. https://www.medicalprotection.org/uk/articles/nitrofurantoin-complicatio...
3. https://cks.nice.org.uk/topics/urinary-tract-infection-lower-women/manag...