The main concept is how the WHO-UMC causality assessment classifies the strength of evidence that a drug caused an adverse reaction. This system uses six categories to express certainty: Certain; Probable/Likely; Possible; Unlikely; Conditional/Unclassified; and Unassessable (or Cannot be judged). The idea is to capture increasing doubt about causality, from clear-cut to unresolved. Among the options, the one that best matches this full set includes Certain, Probable/Likelihood, Possible, and Unassessable (noting that Unassessable can be named differently). The other choices omit two categories, so they don’t fully represent the standard scheme. Recognizing these categories helps you interpret how strong the evidence is and informs clinical or regulatory decisions.

Activated charcoal works by binding many ingested toxins in the gut, reducing their absorption into the bloodstream. Because it is most effective while the toxin remains in the GI tract, timing matters: it’s generally considered within about one hour of ingestion, though some substances may permit a longer window. It should only be used when the patient can protect their airway and there is no GI obstruction or risk of perforation, since aspiration or physical block can cause serious harm. The best option reflects these principles: use activated charcoal if the ingestion occurred within roughly one hour (with possible exceptions for certain substances), and only when there is no airway protection problem or GI obstruction. It is contraindicated for caustic substances and hydrocarbons due to the risk of serious injury or aspiration, and if the patient cannot protect the airway, charcoal should not be given. Other choices are less appropriate because charcoal is not universally indicated for all ingestions or for asymptomatic patients, and it’s not a general treatment for alcohols. Pregnancy status alone does not determine its use or prohibition.

The main idea is that spontaneous reporting systems like FAEMS collect reports of adverse events, but they don’t provide reliable denominators. To calculate a rate, you need both a numer and a defined population at risk (or exposure data) over a specific time. FAEMS can tell you that an adverse event has been reported, i.e., that occurrence has been observed within the system, but it cannot tell you how often that event happens in the broader population. Underreporting, reporting biases, and missing exposure data mean true rates—such as incidence or prevalence—cannot be established from FAEMS alone. To determine population-based rates, you’d need active surveillance or studies with known exposure numbers and a defined population.

The key idea is how digoxin affects potassium handling in the body. Digoxin inhibits the Na+/K+ ATPase pump on cell membranes. When this pump is blocked, potassium tends to move out of cells into the extracellular space. In an acute overdose, this leads to a rise in serum potassium—hyperkalemia—which is a common and important finding and it also signals a potentially severe, life-threatening toxicity. This mechanism is why hyperkalemia is the classic electrolyte abnormality associated with acute digoxin toxicity. While low potassium can increase the risk of digoxin toxicity in other scenarios (because digoxin binds more readily when K+ is low), the immediate, characteristic electrolyte change seen with an acute overdose is elevated potassium. Hypercalcemia and hypomagnesemia aren’t the hallmark findings of acute digoxin toxicity.