IBCLC - Certification Pharmacology and Toxicology Questions and Answers 1 — Questions and Answers
Question 1: A breastfeeding mother of a 3-week-old infant is diagnosed with mastitis and prescribed dicloxacillin. She is concerned about the medication's safety for her infant. What is the most appropriate information for the IBCLC to provide?
- Advise her to "pump and dump" for 24 hours after each dose to minimize infant exposure.
- Reassure her that dicloxacillin is generally considered compatible with breastfeeding and to continue nursing frequently, as this helps resolve the mastitis. (Correct answer)
- Suggest she ask her physician to switch to a tetracycline antibiotic instead.
- Inform her that any antibiotic use requires temporary cessation of breastfeeding.
Correct answer: Reassure her that dicloxacillin is generally considered compatible with breastfeeding and to continue nursing frequently, as this helps resolve the mastitis.
Dicloxacillin is a penicillin-class antibiotic commonly used for mastitis and is considered safe for use during lactation. It has very low transfer into breast milk, and the Relative Infant Dose (RID) is far below the level of concern. Continuing to breastfeed frequently is a critical component of mastitis treatment, as it helps to drain the breast and resolve the infection. Unnecessarily interrupting breastfeeding can worsen the condition.
Question 2: A mother who is breastfeeding her 4-month-old infant reports a sudden and significant decrease in her milk supply. She mentions she recently started taking an over-the-counter medication for cold symptoms. Which of the following active ingredients is the MOST likely cause of her reduced milk production?
- Pseudoephedrine (Correct answer)
- Guaifenesin
- Dextromethorphan
- Acetaminophen
Correct answer: Pseudoephedrine
Pseudoephedrine, a common decongestant, is known to decrease milk supply, sometimes significantly, by reducing serum prolactin levels. The other medications listed—guaifenesin (an expectorant), dextromethorphan (a cough suppressant), and acetaminophen (an analgesic)—are not typically associated with a reduction in milk supply and are generally considered compatible with breastfeeding.
Question 3: When evaluating a medication's safety for a breastfed infant, the Relative Infant Dose (RID) is a key parameter. What does the RID represent?
- The total milligrams of the drug the infant receives in 24 hours.
- The ratio of the drug's concentration in breast milk compared to the mother's plasma.
- The infant's dose via milk (in mg/kg/day) as a percentage of the mother's dose (in mg/kg/day). (Correct answer)
- The time it takes for half of the drug to be eliminated from the mother's milk.
Correct answer: The infant's dose via milk (in mg/kg/day) as a percentage of the mother's dose (in mg/kg/day).
The Relative Infant Dose (RID) is the standard metric for quantifying infant drug exposure through breast milk. It is calculated by dividing the infant's weight-adjusted daily dose from milk by the mother's weight-adjusted daily dose and is expressed as a percentage. An RID of less than 10% is generally considered acceptable for most medications.
Question 4: A client with postpartum depression is breastfeeding her 6-week-old infant. Her physician is considering prescribing a selective serotonin reuptake inhibitor (SSRI). Which of the following SSRIs is generally preferred for lactating individuals due to its low transfer into breast milk and extensive safety data?
- Fluoxetine
- Citalopram
- Sertraline (Correct answer)
- Paroxetine
Correct answer: Sertraline
Sertraline is widely considered a preferred SSRI for use during lactation. It has low passage into breast milk, a relatively short half-life, and infant serum levels are typically low or undetectable. While paroxetine also has low milk transfer, sertraline often has more extensive data supporting its use. Fluoxetine has a very long half-life and an active metabolite, which can lead to accumulation in the infant.
Question 5: A mother reports daily use of cannabis (marijuana) and wants to know if it is safe to continue breastfeeding her 2-month-old infant. Which of the following statements provides the most accurate information?
- Pumping and discarding milk for 12 hours after use will eliminate any risk to the infant.
- As long as the mother does not feel impaired, there is no risk of exposure to the infant through her milk.
- THC is fat-soluble, concentrates in breast milk, and has a very long half-life, posing potential risks to infant neurodevelopment. (Correct answer)
- Occasional use is considered safe, but daily use should be avoided.
Correct answer: THC is fat-soluble, concentrates in breast milk, and has a very long half-life, posing potential risks to infant neurodevelopment.
The primary psychoactive component of cannabis, THC, is highly lipid-soluble, which causes it to concentrate in breast milk at levels higher than in the mother's plasma. It is also eliminated very slowly from the body and milk, with a half-life that can be days or even weeks, making a "pump and dump" strategy ineffective. Major health organizations recommend abstaining from cannabis during lactation due to concerns about potential long-term effects on infant neurodevelopment.
Question 6: A breastfeeding mother requires a diagnostic V/Q scan (ventilation/perfusion scan), which uses Technetium-99m macroaggregated albumin (99mTc-MAA). What is the most current, evidence-based recommendation regarding breastfeeding after this procedure?
- She must pump and discard her milk for at least 24 hours.
- Breastfeeding must be permanently discontinued.
- A temporary interruption of 12 hours is required for safety.
- No interruption of breastfeeding is required. (Correct answer)
Correct answer: No interruption of breastfeeding is required.
For many common diagnostic agents using Technetium-99m, including 99mTc-MAA, current evidence and guidelines from authoritative bodies state that no interruption of breastfeeding is necessary. The physical half-life of Tc-99m is short (about 6 hours), and the excretion into breast milk is minimal, resulting in a negligible radiation dose to the infant.
IBCLC - Certification Pharmacology and Toxicology Questions and Answers 1
A breastfeeding mother of a 3-week-old infant is diagnosed with mastitis and prescribed dicloxacillin.
She is concerned about the medication's safety for her infant.
What is the most appropriate information for the IBCLC to provide?