International Board of Certified Lactation Consultant (IBCLC) Practice Exam

Is insulin classified as a high or low molecular weight medication?

1. High molecular weight

2. Low molecular weight

3. Both

4. Depends on the formulation

The correct answer is: High molecular weight

Insulin is classified as a high molecular weight medication. This classification is due to its structure, which is complex and composed of several amino acids, making it larger in size compared to many other small molecule drugs. Insulin, being a peptide hormone, usually consists of 51 amino acids organized into two chains. The distinction of being high molecular weight is important in clinical contexts, as it influences how insulin is administered, its pharmacokinetics, and its overall metabolism in the body. For example, high molecular weight medications often cannot be administered orally since they can be broken down by gastrointestinal enzymes before they can enter systemic circulation, necessitating alternative routes such as subcutaneous injection for insulin. On the other hand, low molecular weight drugs are typically more straightforward in their formulations and absorption, which is why identifying insulin correctly as high molecular weight is crucial for understanding its use in diabetes management.