Routes of Drug Administration: Enteral

Enteral drugs can be administered as liquids, capsules, or tablets through two routes: oral or sublingual. Oral administration involves swallowing the drug, which passes through the gastrointestinal tract and is metabolized by the liver before entering systemic circulation. Sublingual administration places the drug under the tongue, where it diffuses directly into capillaries and bypasses the GI tract and hepatic metabolism for faster absorption.

Certain drugs are vulnerable to destruction by gastric secretions or cause gastric irritation when passing through the stomach. Enteric coating protects these sensitive drugs from stomach acid and only dissolves in the less acidic intestinal environment, allowing safe absorption without damage or side effects.

Controlled-release formulations are engineered to release drugs slowly and uniformly over an extended period, promoting consistent absorption. This prolonged action is particularly beneficial for drugs with short half-lives, as it reduces the frequency of dosing and minimizes undesired side effects while maintaining therapeutic effectiveness.

The sublingual route is advantageous for drugs unstable in gastric secretions or rapidly metabolized by the liver. The drug diffuses into the capillary network beneath the tongue and is directly absorbed into systemic circulation, bypassing the GI tract and liver metabolism for more effective medication delivery to the body.

Oral drugs pass through the gastrointestinal tract and are metabolized by the liver before entering systemic circulation, which can reduce drug effectiveness. Sublingual drugs bypass both the GI tract and hepatic metabolism, allowing direct absorption into systemic circulation and preserving the drug's potency for conditions requiring rapid or more efficient delivery.

While passing through the stomach, certain drugs may be destroyed by gastric secretions or cause gastric irritation. These challenges are addressed through enteric coating, which shields the drug from stomach acid, or by using the sublingual route to avoid gastric exposure entirely and ensure safe, effective drug delivery.

Enteral administration through the mouth offers convenient, non-invasive drug delivery via oral or sublingual routes. While oral drugs undergo hepatic metabolism and GI tract exposure, sublingual drugs bypass these processes. Understanding enteral administration helps contextualize additional routes of drug administration and factors affecting drug response in pharmacological treatment.