What should be administered to a child within 1 hour of a tricyclic antidepressant overdose if they exceeded 4 mg/kg?

In cases of tricyclic antidepressant (TCA) overdose, especially when the ingested dose exceeds 4 mg/kg, prompt treatment is crucial to mitigate toxicity and prevent severe complications. Administering activated charcoal within one hour of ingestion is a critical step in managing this type of overdose.

Activated charcoal works through the process of adsorption, binding to the toxic substance in the gastrointestinal tract and preventing its absorption into the bloodstream. The effectiveness of activated charcoal diminishes significantly after one hour due to gastrointestinal transit and absorption processes that may occur following ingestion. This makes the timing of the administration of activated charcoal essential in the context of overdose management.

Using other approaches, such as sodium bicarbonate, may be necessary to address specific complications from TCA toxicity, such as arrhythmias or metabolic acidosis, but they wouldn’t be the initial intervention recommended solely for reducing drug absorption. Intravenous fluids are supportive and may be necessary but do not directly counteract the overdose's effect like activated charcoal does. Naloxone is primarily used to reverse opioid overdoses and is not indicated for TCA toxicity.

Thus, the administration of activated charcoal is vital for reducing absorption of the tricyclic antidepressant and should be a priority in this scenario.