A nurse is preparing to administer verapamil 0.1 mg/kg via intermittent IV bolus over 2 min.

Available is verapamil 2.5 mg/mL. The client weighs 165 Ib. How many mL should the nurse administer?

Choice A rationale

Magnesium levels within the normal range (1.3 to 2.1 mEq/L) are important for overall electrolyte balance, but sodium polystyrene sulfonate specifically targets potassium. While hyperkalemia can sometimes be associated with other electrolyte imbalances, a normal magnesium level does not directly indicate a therapeutic response to sodium polystyrene sulfonate, as its primary action is not on magnesium.

Choice B rationale

Calcium levels within the normal range (9 to 10.5 mg/dL) are essential for various physiological functions. Sodium polystyrene sulfonate primarily exchanges sodium ions for potassium ions, not calcium. Therefore, a normal calcium level does not reflect a therapeutic response to the medication, which is specifically aimed at reducing elevated potassium levels.

Choice C rationale

Sodium levels within the normal range (136 to 145 mEq/L) are crucial for fluid balance and neurological function. Sodium polystyrene sulfonate exchanges sodium for potassium, meaning it increases the body's sodium load. While a normal sodium level is desirable, it does not directly indicate the therapeutic efficacy of the medication in reducing potassium.

Choice D rationale

Potassium 4.8 mEq/L (3.5 to 5 mEq/L) indicates a therapeutic response. Sodium polystyrene sulfonate is an ion-exchange resin used to treat hyperkalemia by exchanging potassium ions for sodium ions in the gastrointestinal tract. A potassium level returning to within the normal range, from a previously elevated state, signifies that the medication has effectively lowered the excess potassium.

Choice A rationale

Restlessness, also known as akathisia, is not a typical expected adverse effect of ondansetron. Ondansetron primarily acts as a selective 5-HT3 receptor antagonist, blocking serotonin's emetogenic effects in the chemoreceptor trigger zone and gastrointestinal tract. Common adverse effects are generally mild, including headache, constipation, or diarrhea, with neurological effects like restlessness being rare and atypical for this drug's primary mechanism.

Choice B rationale

Ondansetron should be administered prophylactically, typically 30 minutes *before* chemotherapy, to achieve optimal antiemetic effect. Its mechanism involves blocking serotonin receptors that, when activated by chemotherapy, trigger nausea and vomiting. Pre-emptive administration ensures therapeutic drug levels are present to counteract the emetogenic stimuli effectively before their onset.

Choice C rationale

Acute nausea and vomiting associated with chemotherapy can persist for significantly longer than 12 hours, often lasting for 24 to 48 hours or even longer depending on the specific chemotherapeutic agent and its emetogenic potential. The duration of emesis is highly variable and directly related to the drug's pharmacokinetic profile and the extent of serotonin release.

Choice D rationale

If nausea persists despite ondansetron administration, it indicates an inadequate antiemetic response, likely due to the complex neurochemical pathways involved in chemotherapy-induced nausea and vomiting. This often necessitates a multi-modal approach, involving the addition of other antiemetic agents like corticosteroids (e.g., dexamethasone) or neurokinin-1 receptor antagonists (e.g., aprepitant) to target different emetogenic pathways for more complete symptom control.