Calcium channel antagonists and lactation: an update

Pharmacokinetics of amlodipine besylate at delivery and during lactation

BACKGROUND

Amlodipine is rarely used in the treatment of pregnant hypertensive women due to limited pharmacokinetic data during pregnancy and the postpartum period.

OBJECTIVE

To evaluate the pharmacokinetics of amlodipine besylate in the peri-partum period including quantities of placental passage, breast milk excretion and infant exposure.

STUDY DESIGN

This was a prospective study of pregnant women who were prescribed 5 mg of amlodipine daily for treatment of chronic hypertension and delivered at term. Cord and maternal blood samples were collected at delivery. On postpartum day 2, six paired maternal plasma and breast milk samples were obtained at 4, 6, 8, 12, 15 and 24 h following amlodipine dosing. Infant plasma samples were collected 24-48 h after delivery. All samples were analyzed for amlodipine concentration. A one compartment, first-order model was used to calculate pharmacokinetic estimates for maternal plasma.

RESULTS

Of the 16 patients enrolled in the study, 11 had cord blood and maternal serum collected at delivery, of which only 6 produced sufficient breast milk for sampling. Amlodipine was detected in infant cord blood plasma with a mean concentration of 0.49 ± 0.29 ng/mL compared to mean maternal serum level of 1.27 ± 0.84 ng/mL. Amlodipine concentrations in both in breast milk and infant plasma were undetectable at the lower limit of assay detection (<0.1 ng/mL). In the immediate postpartum period, the amlodipine elimination half-life was 13.7 ± 4.9 h, the area under the curve was 53.4 ± 19.8 ng*h/mL and the peak concentration was 2.0 ± 1.0 ng/mL.

CONCLUSIONS

Amlodipine does cross the placenta in measurable quantities, but is not detected in breast milk or infant plasma at 24-48 h of life indicating that it is likely safe to use during the peripartum period.

Medications and Breast-Feeding: A Guide for Pharmacists, Pharmacy Technicians, and other Healthcare Professionals Part II

Objective:

To provide a guide for practicing pharmacists, pharmacy technicians, and other healthcare professionals so that they are able to counsel and advise breast-feeding mothers and fellow healthcare professionals on the safety and use of common cardiology and general medications during breast-feeding.

Data Sources:

Primary texts used by the breast-feeding community ( Medications and Mothers' Milk, Drugs in Pregnancy and Lactation, Drugs and Human Lactation) were searched, as well as Micromedex, MEDLINE, PubMed, EMBASE, and EMBASE2 (1984–February 2004).

Study Selection/Data Extraction:

Multiple sources were used wherever available to validate the data, and primary articles were used to verify all tertiary source information. Search terms included breast-feeding, lactation, nursing, and medications, as well as specific drug names.

Data Synthesis:

Concerns regarding medication use during breast-feeding have caused mothers to either discontinue nursing or not take necessary medications. Complete avoidance of medications or cessation of breast-feeding is often unnecessary. Although there are drugs that can be harmful to nursing infants, breast milk concentrations of most drugs are insufficient to cause any harm.

Conclusions:

Having objective and reliable information on medications enables pharmacists, pharmacy technicians, healthcare providers, and mothers to make educated decisions regarding drug therapy and breast-feeding.

[Hypertension and pregnancy: Post-partum period]

Post-partum period is associated with specific characteristics in women with gestational disorders or preeclampsia. For breastfeeding women, the choice of antihypertensive treatment should take into account the impact on child health. The impact of breastfeeding on health mother must be also discussed. Moreover, for lactation inhibition, bromocriptine should not be used, especially in the context of gestational disorders. In post-partum period, the best contraceptive strategy is only-progestin contraception or non-hormonal contraceptives use. However, this choice will depend on the stabilization or normalization of blood pressure in early post-partum period. Finally, several consultations should be suggested: an information and announcement to explain the consequences of these gestational disorders and organize their multidisciplinary management and follow-up. A preconceptional consultation takes its place to anticipate potential recurrent preeclampsia or gestational hypertension and to schedule a future pregnancy in optimal conditions.

Hypertension in the postpartum woman: clinical update for the hypertension specialist

Hypertension can persist from pregnancy or present de novo in the postpartum period and continue to pose a risk to maternal well-being. These risks are magnified as many patients present after hospital discharge and go unrecognized because of decreased medical surveillance after delivery. Guidelines for the management of postpartum hypertension are lacking, often resulting in imprecise diagnoses and incorrect treatment strategies. As hypertension specialists are called upon to provide advice to obstetricians regarding the management of hypertension in the postpartum period, it becomes important for the hypertension specialist to develop expertise in the evaluation and treatment of hypertensive women during the postpartum period. The purpose of this clinical review article is to provide an approach to the management of postpartum hypertension.

Time-dependent up-regulation of Ca(2+) channels in vas deferens of newborn rats fed with breast milk of mothers under treatment with nifedipine

Our aim was to check for calcium channel maturation and regulation on newborn rats during breastfeeding by mothers treated with the L-type calcium channel blocker nifedipine. Contractions by KCl and radioligand binding techniques were used to verify if Ca(2+) channels are modified in rat vas deferens of 40-day old litters that were breastfed by mothers injected daily with nifedipine during nursery. Injections were applied in the beginning (1st until 8th day), middle (9th until 16th day), or end (17th until 24th day) of nursery, to verify the period of highest susceptibility of newborn to nifedipine receptor regulation. Contractile responses revealed that only after the middle period of treatment of mothers the maximal effects (E(max)) induced in pups by KCl were increased by about 35%, without changes of apparent affinity (pD(2)). Additionally, binding studies with [(3)H] Isradipine in cell membrane preparations showed a greater density (B(max)) of Ca(2+) channels by about 55%, without changes of affinity (K(d)). Changes were not detected after treatment of mothers in the beginning or end of breastfeeding. In addition, in vas deferens of 60-day old litters, the E(max) returned to control values, showing that changes were not persistent. Moreover, body and vas deferens weights and blood testosterone of newborn were never changed. The histology of mammary gland was similar for treated and control mothers, suggesting a stable milk production. It is concluded that nifedipine treatment of mothers, if made during the 9th to 16th day of lactation, produced a short lasting reversible up-regulation of L-type Ca(2+) channels.

Angiotensin converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) and lactation: an update

Angiotensin converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) are commonly used for the treatment of hypertension. ACEIs have been promoted as first-line therapy for selected patients with chronic hypertension and for the prevention of diabetic nephropathy, thus creating the potential for frequent ACEI exposure among women of childbearing age. ARBs are the most recent addition to the available options for antihypertensive agents. This review specifically focuses on the most up-to-date information regarding these newer antihypertensives with regard to lactation.