International Board of Certified Lactation Consultant (IBCLC) Practice Exam

What percentage of protein binding is regarded as high and potentially safe for breastfeeding?

1. Above 80%

2. Above 90%

3. Above 95%

4. Above 100%

The correct answer is: Above 90%

In pharmacology, the percentage of protein binding refers to how much of a drug in the bloodstream is attached to serum proteins, which affects the drug's distribution and availability in the body. Generally, a high percentage of protein binding is considered advantageous in the context of breastfeeding for several reasons. A drug that is highly protein-bound (above 90%) is less free to cross biological membranes, including the blood-brain barrier and breast tissue, which means it is less likely to enter breast milk. This helps ensure that the concentration of the drug that infants are exposed to through breastfeeding is minimized, thereby reducing potential risks. Choosing a threshold above 90% for high protein binding reflects established guidelines in pharmacokinetics that indicate that at this level, the risk of a significant amount of the drug being transmitted into breast milk is lower. This threshold is crucial for healthcare providers when considering medication use in breastfeeding mothers, aiming to ensure both maternal health and infant safety. Other options reflect considerations that are not typically used in clinical settings. For example, a binding percentage above 95% may be seen as very high, but guidelines usually consider the 90% mark as a practical and clinically relevant threshold for assessing safety during breastfeeding. The concept of a percentage above 100