A nurse is caring for a client with asthma who is prescribed metoprolol. The nurse should monitor the client for which of the following?

Choice A reason: Peak level is the correct term to describe the highest concentration of a drug in the blood after it is administered. Peak level is also known as peak plasma concentration or Cmax, and it reflects the rate and extent of drug absorption. Peak level is influenced by factors such as the route of administration, the dose, the formulation, and the bioavailability of the drug. Peak level is important to monitor for drugs that have a narrow therapeutic range, meaning that there is a small difference between the effective and toxic doses. The nurse should measure the peak level at the appropriate time after the drug administration, and adjust the dose or the frequency as needed to achieve the desired therapeutic effect and avoid adverse effects .

Choice B reason: Halflife is not the correct term to describe the highest concentration of a drug in the blood after it is administered. Halflife is the time it takes for the concentration of a drug in the blood to decrease by 50%. Halflife reflects the rate of drug elimination, which depends on factors such as the metabolism and excretion of the drug. Halflife is important to determine the dosing interval and the time to reach steady state. The nurse should consider the halflife of the drug when prescribing or administering the drug, and avoid drug accumulation or subtherapeutic levels .

Choice C reason: Trough level is not the correct term to describe the highest concentration of a drug in the blood after it is administered. Trough level is the lowest concentration of a drug in the blood before the next dose is given. Trough level reflects the balance between drug absorption and elimination, and it indicates the minimum effective concentration of the drug. Trough level is important to monitor for drugs that have a narrow therapeutic range, meaning that there is a small difference between the effective and toxic doses. The nurse should measure the trough level just before the next dose of the drug, and adjust the dose or the frequency as needed to achieve the desired therapeutic effect and avoid adverse effects .

Choice D reason: Steady state is not the correct term to describe the highest concentration of a drug in the blood after it is administered. Steady state is the condition when the rate of drug administration is equal to the rate of drug elimination, and the concentration of the drug in the blood remains constant. Steady state is usually reached after four to five halflives of the drug, and it reflects the optimal therapeutic level of the drug. Steady state is important to maintain for drugs that have a long halflife or a narrow therapeutic range, meaning that there is a small difference between the effective and toxic doses. The nurse should ensure that the drug is administered at regular intervals and at the appropriate dose to achieve and maintain steady state.

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.