A nurse in the emergency department is caring for a client who took 3 nitroglycerin tablets sublingually for chest pain. The client reports relief from the chest pain but now he is experiencing a headache. Which of the following statements should the nurse make?

Cytotoxic hypersensitivity is a type of hypersensitivity that involves the production of IgG or IgM antibodies that bind to antigens on the surface of cells, leading to cell destruction by complement activation or antibody-dependent cellular cytotoxicity. Myasthenia gravis is an example of a cytotoxic hypersensitivity, as it is caused by autoantibodies that target the acetylcholine receptors on the muscle cells, impairing neuromuscular transmission and causing muscle weakness.

Delayed hypersensitivity is a type of hypersensitivity that involves the activation of T cells and macrophages, leading to inflammation and tissue damage after several hours or days of exposure to an antigen. Examples of delayed hypersensitivity include contact dermatitis, tuberculin skin test, and transplant rejection.

Immediate hypersensitivity is a type of hypersensitivity that involves the production of IgE antibodies that bind to mast cells or basophils, leading to degranulation and release of histamine and other mediators, causing anaphylaxis, urticaria, or allergic rhinitis within minutes of exposure to an antigen.

Immune complex-mediated hypersensitivity is a type of hypersensitivity that involves the formation of antigen- antibody complexes that deposit in tissues or blood vessels, leading to complement activation and inflammation, causing vasculitis, glomerulonephritis, or serum sickness within hours or days of exposure to an antigen.

Phenytoin is an anticonvulsant medication that is used to prevent and treat seizures. It works by stabilizing the electrical activity of the brain and reducing the spread of abnormal impulses. Phenytoin is usually taken for life or until the seizures are controlled by other means, such as surgery or diet. The client should not stop taking phenytoin without consulting their doctor, as this can cause withdrawal symptoms or increase the risk of seizures.

The other options are correct and indicate that the client understands the discharge teaching because:

1. "I have made an appointment to see my dentist next week." This statement is correct because phenytoin can cause gingival hyperplasia, which is an overgrowth of gum tissue that can lead to bleeding, infection, or difficulty chewing. The client should practice good oral hygiene and see their dentist regularly to prevent or treat this condition.

1. "I will notify my doctor before taking any other medications." This statement is correct because phenytoin can interact with many other medications, such as antibiotics, anticoagulants, oral contraceptives, or antacids. These interactions can affect the blood levels and effectiveness of phenytoin or the other medications, causing adverse effects or reduced seizure control. The client should inform their doctor of any other medications they are taking or planning to take, including over-the-counter, herbal, or dietary supplements.
2. "I know that I cannot switch brands of this medication." This statement is correct because different brands of phenytoin may have different formulations or bioavailability, which can affect the absorption and metabolism of the drug. Switching brands can cause changes in the blood levels and effectiveness of phenytoin, leading to toxicity or reduced seizure control. The client should always use the same brand of phenytoin and check with their pharmacist if they notice any changes in the appearance or labeling of their medication.