A pregnant patient is in premature labor. Which class of drug will you question?

Choice A Reason:

Beta2 activation results in bronchodilation. This is a well-known effect where the activation of beta2 adrenergic receptors in the smooth muscle of the airways leads to relaxation and widening of the airways, making it easier to breathe. This effect is commonly utilized in the treatment of asthma and other respiratory conditions.

Choice B Reason:

Beta2 activation also results in glycogenolysis. This process involves the breakdown of glycogen into glucose, which increases blood sugar levels. This effect is part of the body’s response to stress, providing additional energy for the “fight or flight” response.

Choice C Reason:

Beta2 activation results in vasodilation of skeletal muscles. This means that the blood vessels supplying the skeletal muscles widen, increasing blood flow to these muscles. This effect helps to deliver more oxygen and nutrients to the muscles during periods of increased activity.

Choice D Reason:

This is the correct answer. Beta2 activation does not result in the contraction of uterine muscle; rather, it causes relaxation of the uterine smooth muscle. This effect is beneficial in preventing premature labor by reducing uterine contractions. Therefore, the statement that beta2 activation results in contraction of uterine muscle is incorrect and indicates a need for further teaching.

Choice A Reason:

To determine how much of the medication remains in the body after a certain period, we need to understand the concept of half-life. The half-life of a medication is the time it takes for the concentration of the drug in the bloodstream to reduce by half. For Medication A, the half-life is 3 hours. After 12 hours, which is four half-lives, the amount of medication remaining can be calculated step by step.

Choice B Reason:

Let’s break down the calculation. Initially, the patient receives 400 mg of Medication A. After the first half-life (3 hours), the amount of medication remaining is 400 mg ÷ 2 = 200 mg. After the second half-life (6 hours), the amount remaining is 200 mg ÷ 2 = 100 mg. After the third half-life (9 hours), the amount remaining is 100 mg ÷ 2 = 50 mg. Finally, after the fourth half-life (12 hours), the amount remaining is 50 mg ÷ 2 = 25 mg. Therefore, 375 mg is not a correct answer.

Choice C Reason:

Similarly, 150 mg is not correct. As shown in the detailed calculation, the amount of medication decreases by half every 3 hours. After 12 hours, the remaining amount is 25 mg, not 150 mg. This choice does not align with the half-life calculation.

Choice D Reason:

This is the correct answer. The step-by-step calculation shows that after 12 hours, which is equivalent to four half-lives, the amount of Medication A remaining in the patient’s body is 25 mg. This demonstrates the principle of half-life and how the concentration of a drug decreases over time.