Final answer:
For a patient who has ingested a topical antihistamine decongestant like imidazolines, the appropriate treatment is activated charcoal and observation. In case of a systemic infection treatable at home, oral administration of antibiotics is preferred. For anaphylactic shock, epinephrine is the first-line treatment.
Step-by-step explanation:
The appropriate treatment for a patient following the ingestion of a topical antihistamine decongestant, like those found in imidazolines, is Activated charcoal and observation (A). This approach is used to bind the toxin and prevent its absorption into the bloodstream, and observation is important to monitor the patient for any signs of systemic effects. It is essential to quickly assess the situation because imidazolines can cause serious systemic effects if absorbed. Gastric lavage (D) is not typically recommended for imidazoline ingestion as it must be done within an hour of ingestion, and the risks often outweigh the benefits. Treatment options B (IV fluids and antibiotics) and C (Antidote administration) are not applicable for imidazoline toxicity.
For a systemic infection that can be treated at home, the most convenient and appropriate route of administration is oral (A). Intravenous (B) or parenteral (D) administration generally requires professional medical assistance. Topical treatment (C) is not used to treat systemic infections.
Epinephrine (a) is the drug used to counteract the effects of anaphylactic shock. Follow-up treatment may include antihistamines and corticosteroids to prevent late-phase reactions.