Routes of Drug Administration: Enteral

Drugs administered through the enteral route can be liquid or in the form of capsules or tablets. Administration by mouth can be oral or sublingual.

Oral drugs pass through the GI tract and are metabolized by the liver.  Then they are absorbed into the systemic circulation.

While passing through the stomach, certain drugs may be destroyed by gastric secretions, or they may cause gastric irritation.

For such drugs, enteric coating is used, which protects the drug from stomach acid and dissolves it in the less acidic intestine.

Controlled-release preparations can facilitate slow and uniform absorption of drugs.

The longer duration of action is useful for drugs with short half-lives as it reduces the frequency of administration. The formulation also reduces undesired effects.

For drugs that are unstable in gastric secretions or get rapidly metabolized by the liver, the sublingual route proves beneficial, wherein the drug diffuses into the capillary network under the tongue and is directly absorbed into the systemic circulation, bypassing the GI tract and hepatic metabolism.