How does enteric coating affect aspirin's absorption?

Enteric coating changes aspirin’s absorption primarily by delaying where (and when) the drug is released.

What enteric coating does

• Resists dissolution in the stomach (acidic pH): The coating stays intact in the stomach, so aspirin is not released quickly there.
• Dissolves in the intestine (higher pH): The coating breaks down in the duodenum/small intestine, where the pH is higher, releasing aspirin for absorption.

Net effect on absorption

• Slower onset: Because aspirin release is delayed until the intestine, time to peak concentration (Tmax) increases and onset of effect is typically later.
• Often less gastric irritation: Since less drug dissolves in the stomach, stomach-side effects (irritation/ulcer risk) are generally reduced—though this is related to local exposure more than systemic bioavailability.
• Absorption still occurs, but kinetics shift: Overall absorbed amount may be similar or sometimes reduced depending on formulation and individual factors (e.g., intestinal transit time), but the most consistent change is slower, more intestinal release.

Important clinical implication (especially for antiplatelet use)

• For “enteric-coated” aspirin, the delay in absorption can mean a less immediate rise in blood salicylate and potentially less rapid antiplatelet effect right after a dose compared with immediate-release forms.

If you tell me the specific product (e.g., “EC aspirin 81 mg” vs “325 mg”) and what you’re using it for (pain/fever vs heart protection), I can describe the expected absorption timing differences more specifically.