A nurse is caring for a client who has cellulitis and is to begin antibiotic therapy. The client has a history of anaphylactic reaction to penicillin. Which of the following medications is contraindicated for this client?

• Client reports having three to four alcoholic beverages a couple times per week. Phenytoin metabolism is significantly affected by alcohol consumption. Chronic alcohol use increases phenytoin clearance, leading to subtherapeutic drug levels and seizure breakthrough. Conversely, acute alcohol intake inhibits phenytoin metabolism, increasing the risk of toxicity. The client should be counseled to avoid alcohol while on phenytoin therapy.
• Client takes diazepam as needed for anxiety. Diazepam is a CNS depressant that interacts with phenytoin, increasing sedation and the risk of respiratory depression. Both medications can cause drowsiness, dizziness, and impaired coordination, raising the risk of falls and injury. The provider should assess whether diazepam should be discontinued or adjusted when initiating phenytoin therapy.
• Last menstrual period was 3 months ago. Phenytoin is Pregnancy Category D, meaning it poses a significant teratogenic risk, including fetal hydantoin syndrome. The missed menstrual period suggests a possible pregnancy, which must be evaluated before starting phenytoin. A pregnancy test should be performed, and alternative antiseizure medications may need to be considered if pregnancy is confirmed.
• Client is a vegetarian and takes a multivitamin daily. Phenytoin interferes with the absorption of folic acid and vitamin D, both of which are crucial for bone health and red blood cell production. Vegetarians are already at higher risk for folate and vitamin B12 deficiency, making supplementation essential. However, multivitamins containing calcium, magnesium, or iron can decrease phenytoin absorption, reducing its effectiveness. The provider should review the multivitamin’s composition and adjust dosing schedules to prevent interactions.
• Temperature 36.4°C (97.6°F), oral. The client’s temperature is within normal range and does not indicate infection or systemic concerns that would affect phenytoin therapy.
• Heart rate 75/min, Respiratory rate 16/min, Blood pressure 100/74 mm Hg, Oxygen saturation 99% on room air.
  All vital signs are stable and do not indicate hemodynamic instability, respiratory depression, or cardiovascular issues that would contraindicate phenytoin administration.
• Skin color is consistent with genetic background. No rashes or lesions. The client has varicose veins. There are no signs of drug hypersensitivity reactions or dermatologic conditions that would require stopping phenytoin therapy.
• S1 S2 auscultated. No murmurs. All peripheral pulses 2+. Lung sounds clear bilaterally.
  There are no cardiopulmonary concerns that would indicate contraindications to phenytoin.
• Abdomen soft, nontender. Normoactive bowel sounds in all 4 quadrants. Last bowel movement was 3 days ago. Voids four to five times a day. Urine is clear, yellow, and odorless. Mild constipation is noted, but this is not a contraindication for phenytoin. The client should be encouraged to increase fiber and fluid intake to prevent worsening constipation, which can sometimes be a side effect of phenytoin.
• Alert and oriented to person, place, and time. Client has full range of motion and is able to maintain flexion against resistance in all four extremities. There are no neurological deficits requiring immediate intervention, and the client's baseline mental status is intact.

A. Drowsiness. Alendronate, a bisphosphonate used to treat osteoporosis, does not cause drowsiness. It primarily affects bone metabolism rather than the central nervous system. If a client experiences drowsiness, it is likely due to another cause rather than the medication itself.

B. Dyskinesia. Dyskinesia refers to involuntary movements often associated with neurological disorders or medications affecting dopamine, such as antipsychotics or Parkinson’s medications. Alendronate does not affect dopamine or the nervous system, making dyskinesia an unlikely adverse effect.

C. Musculoskeletal pain. A known side effect of alendronate is musculoskeletal pain, including bone, joint, and muscle discomfort. This occurs due to the medication’s effects on bone remodeling and turnover. While mild pain may resolve on its own, persistent or severe pain should be reported to the provider as it may require dose adjustment or discontinuation.

D. Weight gain. Alendronate does not cause weight gain. It primarily acts on bone tissue to inhibit osteoclast-mediated bone resorption, preventing further bone loss. Clients experiencing unexplained weight gain should be evaluated for other potential causes, such as metabolic conditions or lifestyle factors.