+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Altered methadone pharmacokinetics in methadone-maintained pregnant women

Altered methadone pharmacokinetics in methadone-maintained pregnant women

Journal of Pharmacology and Experimental Therapeutics 233(1): 1-6

We studied the influence of human pregnancy on the maternal disposition and effects of methadone. Nine healthy pregnant women who had been on p.o. methadone maintenance for at least 2 months were studied between 20 and 34 weeks of gestation (phase I), 35 and 40 weeks (phase II), 1 to 4 weeks post partum (phase III) and 8 to 9 weeks post partum (phase IV). Two subjects who breast-fed their infants had plasma and breast milk samples collected simultaneously. With or without normalization for dose and body weight, trough plasma concentrations of methadone were significantly lower and total or unbound methadone clearances greater during pregnancy than after delivery. Plasma protein binding of methadone was lower during pregnancy but the difference was only statistically significant between phases I and IV. The greater ratios of urinary excretion of the major metabolites to total and unbound methadone areas under the curve during pregnancy suggests that methadone metabolism was enhanced. The ratios of concentrations of methadone in milk to plasma were constant in two subjects, 0.32 +/- 0.06 and 0.61 +/- 0.07, respectively. Some of the women reported symptoms of methadone withdrawal during pregnancy, even when the daily methadone dose did not change. Because of the lower plasma methadone concentrations, increased methadone doses may be required during pregnancy to achieve methadone maintenance.

Please choose payment method:

(PDF emailed within 1 workday: $29.90)

Accession: 039223157

Download citation: RISBibTeXText

PMID: 3981450

Related references

Amniotic fluid methadone in women maintained on methadone. Mount Sinai Journal of Medicine new York 41(2): 254-259, 1974

Group psychotherapy with methadone-maintained pregnant women. Journal of Substance Abuse Treatment 5(3): 151-161, 1988

Replacement of (R)-methadone by a double dose of (R,S)-methadone in addicts: Interindividual variability of the (R)/(S) ratios and evidence of adaptive changes in methadone pharmacokinetics. European Journal of Clinical Pharmacology 50(5): 385-389, 1996

Excretion of methadone in sweat of pregnant women throughout gestation after controlled methadone administration. Therapeutic Drug Monitoring 32(4): 497-503, 2010

Effectiveness of a smoking cessation intervention for methadone-maintained women: a comparison of pregnant and parenting women. International Journal of Pediatrics 2011: 567056, 2011

Methadone and metabolites in hair of methadone-assisted pregnant women and their infants. Therapeutic Drug Monitoring 34(3): 337-344, 2012

The use of tricyclic antidepressants in methadone maintained pregnant women and infant outcome. Nida Research Monograph 81: 266-272, 1988

Methadone maintenance treatment. Pregnant women taking methadone should be warned about withdrawal symptoms in babies. Bmj 310(6977): 464, 1995

The use of tricyclic anti depressants tca in methadone maintained mm pregnant women and infant outcome. Pediatric Research 21(4 Part 2): 234A, 1987

Motivational enhancement therapy for tobacco dependence in methadone-maintained pregnant women. Drug & Alcohol Dependence 60(Suppl 1): S87, 1 December, 2000

Motivational enhancement therapy for nicotine dependence in methadone-maintained pregnant women. Psychology of Addictive Behaviors 18(3): 289-292, 2004

Impact of timing of methadone initiation on perinatal outcomes following delivery among pregnant women on methadone maintenance therapy in Ontario. Addiction 114(2): 268-277, 2019

Decreased maternal-fetal attachment in methadone-maintained pregnant women: a preliminary study. Journal of the Association for Academic Minority Physicians 6(3): 112-114, 1995

Infections and obstetric outcomes in opioid-dependent pregnant women maintained on methadone or buprenorphine. Addiction 107(Suppl. 1): 83-90, 2012

Obstetrical and neonatal outcomes of methadone-maintained pregnant women: a canadian multisite cohort study. Journal of Obstetrics and Gynaecology Canada 37(3): 252-257, 2015