Which organ is primarily responsible for drug metabolism?

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: The initial phase of drug distribution is not the correct definition of the term 'first pass effect'. Drug distribution is the process by which a drug moves from the bloodstream to the tissues and organs of the body. The initial phase of drug distribution is influenced by factors such as blood flow, tissue permeability, plasma protein binding, and tissue binding. The first pass effect is not related to drug distribution, but to drug metabolism, which is the chemical transformation of a drug in the body.

Choice B reason: The rapid absorption of a drug in the intestine is not the correct definition of the term 'first pass effect'. Drug absorption is the process by which a drug enters the bloodstream from the site of administration. The rapid absorption of a drug in the intestine depends on factors such as the drug formulation, the pH of the gastrointestinal tract, the presence of food or other drugs, and the surface area and motility of the intestine. The first pass effect is not related to drug absorption, but to drug metabolism, which is the chemical transformation of a drug in the body.

Choice C reason: The initial rapid excretion of a drug through the urinary system is not the correct definition of the term 'first pass effect'. Drug excretion is the process by which a drug or its metabolites are eliminated from the body. The initial rapid excretion of a drug through the urinary system is influenced by factors such as the renal blood flow, the glomerular filtration rate, the tubular secretion and reabsorption, and the urine pH. The first pass effect is not related to drug excretion, but to drug metabolism, which is the chemical transformation of a drug in the body.

Choice D reason: The metabolism of a drug before it reaches the systemic circulation is the correct definition of the term 'first pass effect'. Drug metabolism is the process by which a drug is chemically transformed in the body, usually by enzymes in the liver or other tissues. The first pass effect is a phenomenon of drug metabolism that occurs when a drug is administered orally and passes through the gastrointestinal tract and the liver before reaching the systemic circulation. The first pass effect can reduce the bioavailability and the effectiveness of the drug, as some or most of the drug may be metabolized and inactivated before reaching the site of action.