There are times when a nursing mom needs to take certain medications.
Many physicians are simply not well educated on medications and
the safety of taking them while breastfeeding. They may
give information that is inaccurate and/or recommend that a mom
wean to take a medication. Breastfeeding is so very vital
to an infant’s health and development and should be guarded more
vigilantly by our medical community. There truly is a small
number of medications that are contraindicated for breastfeeding.
Dr. Thomas Hale is the leading expert on breastfeeding and medications.
If you have been prescribed a medication and been instructed to
wean to take it, take the time to get the accurate information
on that medication and how it pertains to nursing. Your
proactive manner of handling this could be what saves your breastfeeding
relationship!
L1 |
SAFEST:
Drug which has been taken by a large number of breastfeeding
mothers without any observed increase in adverse effects
in the infant. Controlled studies in breastfeeding women
fail to demonstrate a risk to the infant and the possibility
of harm to the breastfeeding infant is remote; or the product
is not orally bioavailable in an infant. |
L2 |
SAFER:
Drug which has been studied in a limited number of breastfeeding
women without an increase in adverse effects in the infant.
And/or, the evidence of a demonstrated risk which is likely
to follow use of this medication in a breastfeeding woman
is remote. |
L3 |
MODERATELY SAFE:
There are no controlled studies in breastfeeding women,
however the risk of untoward effects to a breastfed infant
is possible; or, controlled studies show only minimal non-threatening
adverse effects. Drugs should be given only if the potential
benefit justifies the potential risk to the infant. |
L4 |
POSSIBLY HAZARDOUS:
There is positive evidence of risk to a breastfed infant
or to breastmilk production, but the benefits of use in
breastfeeding mothers may be acceptable despite the risk
to the infant (e.g. if the drug is needed in a life-threatening
situation or for a serious disease for which safer drugs
cannot be used or are ineffective). |
L5 |
CONTRAINDICATED:
Studies in breastfeeding mothers have demonstrated that
there is significant and documented risk to the infant based
on human experience, or it is a medication that has a high
risk of causing significant damage to an infant. The risk
of using the drug in breastfeeding women clearly outweighs
any possible benefit from breastfeeding. The drug is contraindicated
in women who are breastfeeding an infant. |
There are other categories listed in the "How
to Use this Book" section of Dr. Hale's book. They
include:
Theoretic Infant Dose:
This is an estimate of the maximum likely dose
per kilogram per day that an infant would ingest via milk.
Because the literature is highly variable, I used several methods
to calculate this estimate. First, if the authors provided
milk AUC information, I used this data to estimate the dose to
the infant as it is much more accurate. But more commonly,
the only data provided was the peak milk level, also called Cmax.
In these cases I used this data to derive the theoretic infant
dose. For determining dose I used the standard milk intake
of 150 mL/kg/day multiplied times the concentration of medication
in milk (Cmax/Liter X 0.150 mL/kg/day = TID). Please remember,
this is generally the maximum concentration that
would be transferred. Most often the actual dose to the
infant would be much lower. If you know the maternal dose,
calculate the Relative Infant Dose using the formula on
page 12. It may prove very useful.
Adult Concerns:
This section lists the most prevalent undesired
or bothersome side effects listed for adults. As with most
medications, the occurrence of these if often quite rare, generally
less than 1 - 10% of the time. Side effects vary from one
patient to another and should not be overemphasized, since most
patients do not experience untoward effects.
Pediatric Concerns:
This section lists the side effects noted in
the published literature as associated with medications transferred
via human milk. Pediatric concerns are those effects
that were noted by investigators as being associated with drug
transfer via milk. They are not the effects that would result
from direct administration to the infant. In some sections,
I have added comments that may not have been reported in the literature,
but are well known attributes of this medication and are useful
information to provide the mother so that she can better care
for her infant ("Observe for weakness, apnea").
Drug Interactions:
Drug interactions generally indicate which
medications, when taken together, may produce higher or lower
plasma levels of other medications, or they may decrease or increase
the effect of another medication. These effects may vary
widely from minimal to dangerous. Because some medications
have hundreds of interactions, and because I had limited room
to provide this information, I have listed only those that may
be significant. Therefore please be advised that this section
may not be complete. In several references, I have suggested
that due to the large number of interactions the reader consult
a more complete drug interactions reference. Please remember
that the drugs administered to a mother could interact with those
being administered concurrently to an infant. Example:
Maternal fluconazole and pediatric cisapride.
Alternatives:
Drugs listed in this section may be suitable
alternate choices for the medication listed above. In many
instances, if the patient cannot take the medication, or it is
a poor choice due to high milk concentrations, these alternates
may be suitable candidates. WARNING: The alternates
listed are only suggestions and may not be at all proper for the
syndrome in question. Only the clinician can make this judgment.
For instance, nifedipine is a calcium channel blocker with good
anti-hypertensive qualities, but poor anti-arrhythmic qualities.
In this case, verapamil would be a better choice.
Adult Dosage:
This is the usual adult oral dose provided
in the package insert. While these are highly variable,
I chose the dose for the most common use of the medication.
T 1/2 =
This lists the most commonly recorded adult
half-life of the medication. It is very important to remember
that short half-life drugs are preferred. Use this parameter
to determine if the mother can successfully breastfeed around
the medication, by nursing the infant...then taking the medication.
If the half-life is short enough (1 - 3 hrs), then the drug level
in the maternal plasma will be declining when the infant feeds
again. This is ideal. If the half-life is significantly
long (12 - 24 hrs), and if your physician is open to suggestions,
then find a similar medication with a shorter half-life (compare
ibuprofen with Naproxen). I have provided "Family"
tables in the back of this text, so you can compare family members
for half-lives and other kinetic parameters.
PHL =
This lists the most commonly recorded pediatric
half-life of the medication. Medications with extremely
long half-lives in pediatric patients may accumulate to high levels
in the infant's plasma if the half-life is exceeding long (>12
hrs.). Pediatric half-lives are difficult to find due to
the paucity of studies.
M/P =
This lists the Milk/plasma ratio. This
is the ratio of the concentration of drug in the mother's milk
divided by the concentration in the mother's plasma.
If high (>1 - 5) it is useful as an indicator of drugs that
may sequester in milk in high levels. If low (<1) it
is a good indicator that only minimal levels of the drug are transferred
into milk (this is preferred). While it is best to try to
choose drugs with LOW milk/plasma ratios, the amount of drug which
transfers into human milk is largely determined by the level of
drug in the mother's plasma compartment. even with high
M/P ratios and LOW maternal plasma levels the amount of drug that
transfers is still low. Therefore, the high M/P ratios often
provide an erroneous impression that large amounts of drug are
going to transfer into milk. This simply may not be true.
PK =
This lists the time interval from administration
of the drug, until it reaches the highest level in the mother's
plasma, which we call the Peak. In pharmacology literature
it is most commonly abbreviated Cmax. The peak is when you
do not want the mother to breastfeed her infant, rather, wait
until the peak is subsiding or has at least dropped significantly.
Remember, drugs enter breastmilk as a function of the maternal
plasma concentration. The higher the mom's plasma level,
the greater the entry of the drug into her milk. If possible,
choose drugs that have short peak intervals, and don't let mom
breastfeed when it peaks.
PB =
This lists the percentage of maternal protein
binding. Most drugs circulate in the blood bound to plasma
albumin. if a drug is highly protein bound ti cannot exit
the plasma compartment as well. The higher the percentage
of binding the less likely the drug is to enter the maternal milk.
Try to choose drugs that have high protein binding, in order to
reduce the infants exposure to the medication. Good protein
binding is typically greater than 90%.
Oral =
Oral bioavailability refers to the ability
of a drug to reach the systemic circulation after oral administration.
it is generally a good indication of the amount of medication
that is absorbed into the blood stream of the patient. Drugs
with low oral bioavailability are generally either poorly absorbed
in the gastrointestinal tract, or they are sequestered by the
liver prior to entering the plasma compartment. The oral
bioavailability listed in this text is the adult value; almost
none have been published for children or neonates. Recognizing
this, these values are still useful in estimating if a mother
or perhaps an infant will actually absorb enough drug to provide
clinically significant levels in the plasma compartment of the
individual. The value listed estimates the percent of an
oral dose that would be found in the plasma compartment of the
individual after oral administration. In many cases, the
oral bioavailability of some medications is not listed by manufacturers,
but instead terms such as "Complete", "Nil",
or "Poor" are used. For lack of better data, I
have included these terms when no data is available on the exact
amount (percentage) absorbed.
Vd =
The volume of distribution is a useful kinetic
term that describes how widely the medication is distributed in
the body. Drugs with high volumes of distribution (Vd) are
distributed in higher concentrations in remote compartments of
the body, and may not stay in the blood. For instance, digoxin
enters the blood compartment and then rapidly leaves to enter
the heart and skeletal muscle. Most of the drug is sequestered
in these remote compartments (100 fold). Therefore, drugs
with high volumes of distribution (1 - 20 liter/kg) generally
require much longer to clear from the body than drugs with smaller
volumes (0.1 liter/kg). For isntance, whereas it may only
require a few hours to totally clear gentamycin (Vd = 0.28 l/kg)
it may require weeks to clear amitriptyline (Vd = 10 l/kg) which
has a huge volume of distribution. In addition, some drugs
may have one half-life for the plasma compartment, but may have
a totally different half-life for the peripheral compartment,
as half-life is a function of volume of distribution. For
a complete description of Vd, please consult a good pharmacology
reference. In this text, the units of measure for Vd are
liters/kg.
pKa =
The pKa of a drug is the pH at which the drug
is equally ionic and nonionic. The more ionic a drug is,
the less capable it is of transferring from the milk compartment
to the maternal plasma compartment. Hence, they become trapped
in milk (ion-trapping). This term is useful, because drugs
that have a pKa higher than 7.2 may be sequestered to a slightly
higher degree than one with a lower pKa. Drugs with higher
pKa generally have higher milk/plasma ratios. hence, choose
drugs with a lower pKa.
MW =
The molecular weight of a medication is a significant
determinant as to the entry of that medication into human milk.
Medications with small molecular weights (<200) can easily
pass into milk by traversing small pores in the cell walls of
the mammary epithelium (see ethanol). Drugs with higher
molecular weights must traverse the membrane by dissolving in
the lipid bi-layers, which may significantly reduce milk levels.
As such, the smaller the molecular weight the higher the relative
transfer of that drug into milk. Protein medication (e.g.
Heparin, Insulin), which have enormous molecular weights, transfer
at much lower concentrations and are virtually excluded from human
breastmilk. Therefore, when possible, choose drugs with
higher molecular weights to reduce their entry into milk.
Note: If you have a chronic disease or
condition for which regular medications have been necessary, I
would suggest purchasing a copy of Dr. Hale's book to take with
you to all doctor appointments. Many doctors and specialists
simply aren't aware of how compatible most medications are with
breastfeeding because it just isn't their specialty. Take
the responsibility upon yourself to arrive with the information
in hand that may be needed for your appointment and you will save
yourself many headaches.
From:
Medications and Mothers' Milk (2002) by Thomas W. Hale, PhD
03/2004 |