Bioavailability is:

Correct Answer: D

Rationale: Bioavailability can be 100% (e.g., IV), not always less, so that's false. It's the fraction reaching systemic circulation, not just absorbed, making that incomplete. First-pass metabolism reduces bioavailability, so that's false. Verapamil's oral bioavailability is low (~20-35%), not 80%, due to extensive first-pass metabolism, but the key indicates this as true (possibly a typo; typically false). The correct interpretation aligns with bioavailability as absorption minus extraction, though the key's choice needs context. Verapamil's low bioavailability informs its dosing.

Correct Answer: B

Rationale: Cyanocobalamin, or vitamin B12, is essential for red blood cell production and neurological function, and its deficiency directly leads to pernicious anemia, a condition characterized by large, immature red blood cells due to impaired DNA synthesis. This occurs because B12 is crucial for folate metabolism and erythropoiesis, and without it, anemia develops, often accompanied by neurological symptoms like numbness or tingling. Pellagra, however, results from niacin (vitamin B3) deficiency, manifesting as dermatitis, diarrhea, and dementia-unrelated to B12's role. Rickets stems from vitamin D deficiency, causing bone deformities due to poor calcium absorption, not a B12 issue. Scurvy arises from vitamin C deficiency, leading to collagen breakdown and symptoms like bleeding gums, distinct from B12's hematological effects. Pernicious anemia stands out as the correct outcome because B12 deficiency disrupts bone marrow function, and it often requires pharmacotherapy, such as B12 injections, especially if absorption is impaired (e.g., due to lack of intrinsic factor). This specificity eliminates other conditions, highlighting B12's unique role in blood and nerve health.

Correct Answer: C

Rationale: A large-bore catheter is recommended for whole blood transfusions to allow for the rapid administration of blood products and to prevent hemolysis. Smaller catheters may not accommodate the viscosity of whole blood and could increase the risk of complications. While patient comfort and past experiences are important, the primary consideration is the safe and effective delivery of the transfusion. Therefore, a large-bore catheter is the best choice.

Correct Answer: D

Rationale: Antiemetic drugs are medications used to prevent and treat nausea and vomiting. Therefore, the main action of antiemetic drugs is to prevent vomiting, making option E the correct answer. Antiemetic drugs work by reducing or blocking the signals to the vomiting center in the brain, thus helping to alleviate the symptoms of nausea and prevent vomiting.

Correct Answer: B

Rationale: Valproate is classified as an anti-convulsant medication. It is commonly used to treat seizures, particularly in the management of epilepsy. Valproate works by affecting certain chemicals in the brain to control seizures and stabilize mood in some psychiatric conditions. It is not classified as an anti-diabetic, anti-ulcer agent, or anti-hypertensive medication.