Off-label prescribing during pregnancy in the UK: an analysis of 18,000 prescriptions in Liverpool Women's Hospital.

OBJECTIVE

Large numbers of drugs are prescribed antenatally, many of which are off-label or unlicensed. An off-label medication is one which does have a market authorization, but for a different indication, dose, route or patient group than that for which it is prescribed. The purpose of this study was to determine how commonly these prescriptions are written at Liverpool Women's Hospital (LWH), a unit with 8000 deliveries per annum.

METHODS

All inpatient prescriptions received from antenatal areas at LWH during a 3-month period were analysed. The drugs were divided into categories according to their licence, FDA class and degree of clinical risk.

KEY FINDINGS

Some 17 694 prescriptions of 235 different drugs were prescribed during this period. Thirty-seven (16%) drugs and 4445 (25%) medications prescribed were licensed for use in pregnancy; 57 (24%) drugs and 3363 (19%) of the total prescriptions were off-label but considered safe by the manufacturers (e.g. erythromycin, prochlorperazine and clotrimazole); 138 (58%) drugs and 9722 (55%) prescriptions were cautioned or contraindicated by the manufacturer in pregnancy (e.g. cefalexin, magnesium sulphate and nifedipine). After further investigation into the safety of the off-label medications from the FDA safety profile and with the opinion of a multidisciplinary team, we were able to draw up a list of high-risk off-label medicines. This consisted of 38 drugs (16% of total) and 1735 (10%) of the total prescriptions (e.g. lisinopril, diazepam and morphine).

CONCLUSIONS

A significant number of prescriptions being used in an off-label manner at LWH are high risk. Prescribers need to be aware of the risks associated with these drugs and the possible legal consequences of prescribing and administering them.