Practical, clinical issues concerning drugs in human milk arise frequently in dentistry because mothers present for elective treatment which has been postponed during pregnancy. Treatment provided for nursing mothers may be third molar surgery, periodontal treatment, prophylaxis, endodontic care or dental restorative procedures. Nursing mothers are generally concerned about any possible effect dental treatment, including drugs, may have on their milk or on the nursing infant.
Where single doses of drugs are used, e.g. local anaesthetics or parenterally administered sedatives, the effects on human milk are likely to be minimal. However, where there is any doubt concerning a mother's confidence to continue nursing a child immediately following treatment, she can usually express and store some milk the day before treatment.
Local anaesthetics (e.g. lignocaine, prilocaine) appear in human milk in low concentrations and no adverse effects are known. Anecdotal reports of infants rejecting milk following maternal local anaesthetics, although rare, are often attributed by mothers to a taste change; certainly local anaesthetics have a characteristic bitter taste.
Sedatives such as intravenous midazolam or diazepam are usually given as a single titrated dose. The serum concentration achieved may be relatively high, but for only short periods and doses are not generally repeated. For preference, intravenous sedatives with a short half-life are more suitable during lactation as any possible effect on human milk is restricted. The half-life of midazolam is approximately two hours compared with over 40 hours for diazepam.
When treating nursing mothers, dentists should be familiar with all aspects of the drugs they administer or prescribe; `Drug distribution in human milk' provides an authoritative reference resource.
- National Health and Medical Research Council. Guidelines for dental treatment: dentistry and pregnancy. Canberra: Australian Government Publishing Service, 1993.
- Drugs in dentistry during pregnancy and lactation. In: Woods R. A guide to the use of drugs in dentistry. 12th ed. Sydney: Australian Dental Association, 1996:196-206.