1.5 Routes for Administering Drugs to the Body

• What is a drug?• Structure of the Digestive System• The Mouth and Digestive System• The Stomach• The Small Intestine• The Large Intestine• Drugs and the Digestive System• Delivering Drugs to the Body• Tablets and Capsules• Drugs Swallowed in Liquid Form• Dermal Patches and Subdermal implants• Vitamins

What is a Drug?

• A chemical substance that changes the physiological state of the human body.

• Drugs are used for the prevention, diagnosis and treatment of diseases.

• Eg. Analgesics(pain relievers), anaesthetics, antihistamines, antibiotics, anticoagulants, vaccines, hormone replacements.

• Psychotropic drugs affect the mind and include antidepressants, tranquilisers, appetite suppressants and amphetamines

How to Be Effective as a Drug

• To reach the intended site of action at the correct dosage

• Treats the condition for which it was designed.

• It lasts long enough in the body for it to take effect.

• It only affects the tissue it is designed for.• It has few side effects on other tissues or

body tissues

• Most drugs reach the intended site via the bloodstream.• Some injected directly but most are absorbed through

the digestive system.• Passage is affected by;• The action of the digestive juices, stomach acid and

enzymes• Drugs can be solid tablets/capsules or solutions• Tablets/capsules may be modified so that their

ingredients are released over an extended time rather than all at once.

Structure of the Digestive System

Structure of the Digestive System

The Stomach

The Small Intestine

The Large Intestine

Drugs and the Digestive System

The Large Intestine

Drugs and the Digestive System

Delivering Drugs to the Body

• Vitamins

Tablets and Capsules

• If the active ingredient of a tablet is sensitive to acid, or is irritant to the stomach lining, an enteric coating can be used, which is resistant to stomach acid, and dissolves in the less acidic area of the intestines. Enteric coatings are also used for medicines that can be negatively affected by taking a long time to reach the small intestine, where they are absorbed.

Drugs Swallowed in Liquid Form

Dermal Patches and Subdermal implants

Vitamins