PsychoTropical Research - Dr Ken Gillman, Serotonin Syndrome, Mirtazapine, Dual Action Drugs. Psychotropics and pregnancy - Breast-feeding.

PsychoTropicalResearch, serotonin and serotonin syndrome research.

Psychotropics and pregnancy - Breast-feeding

Psychotropics and pregnancy - Breast-feeding

Date Created: 17/04/1999   Last Modified: 19/01/2002   Last Checked: 21/10/2002

The available data from which to make confident decisions is limited for most psychotropics-- TCAs are the best studied, but there are less than one hundred published cases of mother/infant blood levels in the world literature to date. No single series has more than a handful of cases and often methodology leaves something to be desired.

For full term infants evidence is that amitriptyline, nortriptyline, desipramine and clomipramine are undetectable in infant serum. Sertraline blood levels have proved widely undetectable also.

Even if moderate levels of these drugs to do get through from breast feeding there is no evidence to suggest the likelihood of any significant long term harm. TCAs levels can be monitored in infant blood.

In summary, if antidepressants are being used for major depression for sound clinical indications then the risks from treatment, for both mother and child, are definitely lower than the risks of remaining untreated.

It is important to reconsider the optimal drug treatment where pregnancy or breast feeding is an issue. The great variations in toxicity of members of the same classes or groups of drugs become even more important (see notes re ‘toxicity’ etc). eg:-- It may be wise to avoid more toxic TCAs like doxepin. Drugs with shorter half-lives, linear pharmacokinetics, and no active metabolites would seem preferable (eg sertraline, reboxetine, nortriptyline).

Special factors:- pre term infants have even less mature livers and hence have high conjugated bilirubin levels (due to reduced ability to glucuronidate). This (glucuronidation) may be the best guide of the liver’s ability to metabolise drugs. Normal term neonatal liver enzyme activity levels are about 20% of those in adults and increase steadily during the first year of life. Renal clearance at term is 2-4 ml/min but is only 0.6-0.8 ml/min in preterm infants. They are therefore at greater risk of accumulating drugs from breast milk and will also clear drugs already absorbed from the maternal circulation more slowly. Pre-term infants’ renal and liver function may need to be assessed before exposing them to drugs in breast milk. For TCAs it seems that about 1% of the maternal drug dose (per kg of infant body weight) is ingested via breast milk.

The timing of drug dose relative to feeding may significantly affect the dose absorbed by the infant. TCA concentrations in breast milk are similar to those in plasma. A once daily dose at the time of the last evening feed may minimise infant exposure. In view of genetic variability of drug metaboliser status (via CYP450 enzymes-- see various other notes) it is wise to check the mothers blood levels and take appropriate steps to minimise doses of all drugs.