A 22-year-old man with seasonal allergic rhinitis takes an antihistamine for relief of symptoms. It is successful for him over 90% of the time. Histamine is a natural amine formed by the decarboxylation of which of the following amino acids?

Correct Answer: C

Rationale: Histamine, key in allergies, is derived from histidine via decarboxylation. L-arginine , Lysine , and Tyrosine (E) form other amines. Heparin is a glycosaminoglycan. Histidine's conversion drives allergic responses, blocked by antihistamines.

Correct Answer: A

Rationale: Valproate, commonly known as sodium valproate or valproic acid, is a medication primarily used to treat seizures, including epilepsy. It is an antiepileptic drug that works by increasing the levels of a neurotransmitter called gamma-aminobutyric acid (GABA) in the brain, which helps to calm excessive electrical activity that can lead to seizures. Valproate is considered a first-line treatment for various types of seizures, especially absence seizures and generalized tonic-clonic seizures. It is not used for replacing hormones, maintaining blood glucose levels, or lowering blood pressure.

Correct Answer: A

Rationale: HRT, often involving estrogen, increases thrombophlebitis risk due to enhanced clotting factors. Calf pain signals possible deep vein thrombosis (DVT), a life-threatening side effect requiring immediate assessment, as it could lead to pulmonary embolism. Decreased libido , low-back pain , and fatigue may occur with HRT but are less urgent and not specific to its most dangerous complications. The nurse prioritizes calf pain due to its association with thromboembolism, a well-documented HRT risk, especially in smokers or those with vascular issues, making choice A the critical focus for safety.

Correct Answer: C

Rationale: Heparin is a commonly used anticoagulant medication. It works by inhibiting the formation of blood clots in the body. Anticoagulants like heparin are frequently used to prevent and treat conditions such as deep vein thrombosis (DVT), pulmonary embolism, and during certain medical procedures to reduce the risk of clot formation. Heparin is not used to treat hypertension, diabetes, or as a laxative.

Correct Answer: C

Rationale: Protamine sulfate is a medication that can antagonize the anticoagulant effects of heparin. Heparin works by binding to antithrombin III to enhance its activity, which leads to the inhibition of factor Xa and thrombin. Protamine sulfate, a positively charged molecule, binds to heparin to form a stable complex, neutralizing the anticoagulant effects of heparin. This makes protamine sulfate a useful antidote for heparin overdose or in situations where rapid reversal of heparin is necessary to reduce the risk of bleeding complications. The other options listed - acetylcysteine, naloxone, warfarin sodium, and phenindione - do not have a direct antagonistic effect on the anticoagulant effects of heparin.