What does the term 'first pass effect' refer to?

Choice A reason: Bradycardia is not an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine does not affect the heart rate or blood pressure significantly, and it is not associated with bradycardia, which is a slow heart rate that can cause dizziness, fatigue, or fainting. The nurse should monitor the vital signs of the client after administering diphenhydramine, but bradycardia is not a common or expected outcome.

Choice B reason: Sedation is an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine can cross the bloodbrain barrier and block the histamine receptors in the brain, which are involved in regulating the sleepwake cycle and alertness. Diphenhydramine can cause sedation, sleepiness, drowsiness, dizziness, and impaired coordination, which can affect the performance and safety of the client. The nurse should instruct the client to avoid driving, operating machinery, or performing other tasks that require mental alertness after taking diphenhydramine, and to take the medication at bedtime or as needed for sleep.

Choice C reason: Constipation is not an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine does not affect the gastrointestinal motility or secretion significantly, and it is not associated with constipation, which is a condition of infrequent or difficult bowel movements. The nurse should encourage the client to eat a balanced and highfiber diet, drink plenty of fluids, and exercise regularly to prevent or treat constipation, but diphenhydramine is not a contributing factor.

Choice D reason: Hypertension is not an adverse effect of diphenhydramine. Diphenhydramine is a medication that blocks the action of histamine, a chemical that causes allergic reactions and inflammation. Diphenhydramine can also block the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Diphenhydramine does not affect the blood pressure or the vascular tone significantly, and it is not associated with hypertension, which is a condition of high blood pressure that can cause headaches, chest pain, or stroke. The nurse should monitor the blood pressure of the client after administering diphenhydramine, but hypertension is not a common or expected outcome.

Choice A reason: Dextromethorphan (Robitussin) is not the correct medication for a patient with a productive cough. Dextromethorphan is a cough suppressant that works by acting on the brain to reduce the cough reflex. Dextromethorphan is used for a dry, nonproductive cough that is caused by irritation or inflammation. Dextromethorphan is not effective for a productive cough that produces mucus, and it may even be harmful by preventing the clearance of secretions from the lungs.

Choice B reason: Fluticasone (Flonase) is not the correct medication for a patient with a productive cough. Fluticasone is a corticosteroid that works by reducing inflammation and swelling in the nasal passages. Fluticasone is used for allergic rhinitis, which is a condition that causes sneezing, itching, and runny nose due to an allergic reaction. Fluticasone is not effective for a productive cough that produces mucus, and it may even worsen it by suppressing the immune system and increasing the risk of infection.

Choice C reason: Pseudoephedrine (Sudafed) is not the correct medication for a patient with a productive cough. Pseudoephedrine is a decongestant that works by constricting the blood vessels in the nasal passages and sinuses. Pseudoephedrine is used for nasal congestion, which is a condition that causes stuffy nose and difficulty breathing due to swelling of the mucous membranes. Pseudoephedrine is not effective for a productive cough that produces mucus, and it may even cause side effects such as increased blood pressure, insomnia, and anxiety.

Choice D reason: Guaifenesin (Mucinex) is the correct medication for a patient with a productive cough. Guaifenesin is an expectorant that works by thinning and loosening the mucus in the chest and throat. Guaifenesin is used for a productive cough that produces mucus, as it helps the cough to be more effective and clear the airways. Guaifenesin is generally safe and well tolerated, but it may cause some minor side effects such as nausea, vomiting, and headache.