A nurse is reinforcing teaching with a client who takes lithium carbonate for bipolar disorder.
For which of the following findings should the nurse monitor as an adverse effect of lithium carbonate?.

Step 1: Determine the Medication Concentration

• The total amount of medication in the solution is 250 mg.
• The total volume of the solution is 5 mL.
• To find the concentration per mL:
  250 mg ÷ 5 mL = 50 mg/mL

Step 2: Determine the Required Volume

• The prescribed dose is 500 mg.
• To find the volume needed:
  500 mg ÷ 50 mg/mL = 10 mL

Thus, the nurse should administer 10 mL of the solution to deliver the required 500 mg dose.

The correct answer is Choice B

Choice A rationale: Dantrolene is a direct-acting skeletal muscle relaxant that works by inhibiting calcium release from the sarcoplasmic reticulum in muscle cells, thereby reducing muscle contraction. It is not intended for as-needed use during acute spasms but requires consistent dosing to maintain therapeutic levels. Intermittent use undermines its pharmacokinetics and may lead to subtherapeutic effects. The half-life of dantrolene is approximately 8.7 hours, and steady-state levels are necessary for optimal spasticity control in multiple sclerosis.

Choice B rationale: Dantrolene’s therapeutic effect on muscle spasticity may take several weeks to manifest due to its mechanism of action involving gradual reduction in intracellular calcium availability. If no improvement is noted within 3 months, it may indicate inadequate response or the need for dosage adjustment. Monitoring for efficacy is essential, as prolonged use without benefit increases risk of hepatotoxicity. Liver function tests should be monitored regularly. Normal ALT levels are 7–56 units/L; elevations may signal toxicity.

Choice C rationale: Dantrolene is classified as pregnancy category C, indicating that risk to the fetus cannot be ruled out. Animal studies have shown adverse effects, and there are no adequate human studies confirming safety during pregnancy. Therefore, it is not considered safe without careful risk-benefit analysis. Teratogenicity and fetal toxicity are concerns due to its action on muscle fibers and potential systemic effects. Pregnant clients should consult their provider before initiating or continuing dantrolene therapy.

Choice D rationale: Dantrolene does not directly affect calcium levels in the bloodstream. Its mechanism involves inhibition of calcium release within muscle cells, not systemic calcium metabolism. Routine calcium monitoring is not required unless the client has a separate condition affecting calcium homeostasis. Normal serum calcium levels range from 8.5 to 10.5 mg/dL. The primary lab concern with dantrolene is hepatotoxicity, necessitating regular liver function tests, not calcium surveillance. This statement reflects a misunderstanding of the drug’s effects.