Which organ is primarily responsible for excretion of a medication?

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: Vasoconstriction is the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. This increases the resistance to blood flow and raises the blood pressure. Phenylephrine is used as a vasopressor to treat hypotension, which is a condition of low blood pressure that can cause dizziness, fainting, or organ damage. The nurse should monitor the blood pressure and the peripheral pulses of the patient after administering phenylephrine.

Choice B reason: Bronchodilation is not the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. It has no effect on the beta2 receptors on the bronchial smooth muscle, which are responsible for bronchodilation or widening of the airways. Phenylephrine is not used to treat respiratory conditions, such as asthma or chronic obstructive pulmonary disease, that cause bronchoconstriction or narrowing of the airways. The nurse should assess the respiratory rate and the breath sounds of the patient after administering phenylephrine.

Choice C reason: Diuresis is not the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. It has no effect on the kidney function or the urine output. Phenylephrine is not used to treat fluid retention or edema, which are conditions of excess fluid in the body that can cause swelling, weight gain, or heart failure. The nurse should measure the urine output and the specific gravity of the patient after administering phenylephrine.

Choice D reason: Decreased heart rate is not the desired therapeutic effect of phenylephrine in this context. Phenylephrine is a medication that stimulates the alpha1 receptors on the blood vessels, causing them to constrict or narrow. It has little or no effect on the beta1 receptors on the heart, which are responsible for increasing the heart rate and the contractility. Phenylephrine may actually cause a reflex bradycardia, which is a slow heart rate that occurs when the baroreceptors in the blood vessels sense an increase in blood pressure and send signals to the brain to lower the heart rate. Phenylephrine is not used to treat tachycardia, which is a fast heart rate that can cause palpitations, chest pain, or arrhythmias. The nurse should monitor the electrocardiogram and the heart rate of the patient after administering phenylephrine.