3.4 : 药物递送：肠内途径

Enteral administration of drugs can occur via oral, sublingual, and buccal routes. Oral administration involves swallowing a pill; in sublingual delivery, it is placed under the tongue, while buccal intake positions it between the gums and cheek.

Oral drugs travel through the GI tract, undergo hepatic metabolism, and are absorbed through the intestines into the bloodstream.

However, some drugs may cause gastric irritation or be inactivated by gastric enzymes, or varying pH in the GI tract.

Drugs with protective enteric-coatings release only in the intestine, preventing denaturation or inactivation of acid-sensitive drugs like omeprazole while shielding the stomach from irritants like aspirin.

Controlled-release preparations employ a special coating for gradual drug release, ensuring prolonged action and reducing dosage frequency.

Sublingual and buccal routes enable direct drug diffusion into the blood supply, enhancing absorption. Examples include sublingual nitroglycerin treating angina and buccal midazolam for emergency treatment of epileptic seizures in children.