**Question:** All of the following drugs are administered orally except:

A. Insulin
B. Heparin
C. Pethidine
D. Heparan Sulfate

**Core Concept:** This question is testing the ability to differentiate between drugs that are typically administered via injection and those that can be taken orally. Understanding the various routes of drug administration is crucial for safe and effective drug management.

**Why the Correct Answer is Right:** Insulin, Heparin, and Pethidine are all medications that require injection due to their pharmacokinetic properties. Insulin is a peptide hormone that needs to be administered subcutaneously as it is unstable in the gastrointestinal tract. Heparin is a potent anticoagulant that is given intravenously due to its narrow therapeutic window and potential for severe bleeding complications if given orally. Pethidine, also known as morphine, is an opioid analgesic that is typically administered intravenously or intramuscularly due to its potential for severe GI side effects when taken orally.

**Why Each Wrong Option is Incorrect:** Heparan Sulfate is an anticoagulant that is typically administered subcutaneously or intravenously, but not orally. This is due to its role in blood coagulation and the need to avoid interfering with its function when taken orally.

**Clinical Pearl:** It is essential for medical professionals to understand the appropriate routes of drug administration to ensure patient safety and optimal treatment outcomes. Familiarizing oneself with the pharmacokinetic properties of various medications can prevent medication errors and adverse reactions.

**Correct Answer:**

**A. Insulin**

Heparin

**B. Heparan Sulfate**

**C. Pethidine**

In this case, the correct answer is "B. Heparan Sulfate" as it is an anticoagulant that is typically administered subcutaneously or intravenously, but not orally. The oral administration of heparin can interfere with its anticoagulant properties and lead to severe bleeding complications.