Week 9 Rectal DDS

Rectal Drug Delivery Systems

A method of delivering medications through the rectum for systemic or local effects.

Advantage: First Pass Metabolism

• The process by which the concentration of a drug is significantly reduced before it reaches the systemic circulation.

• Patients unable/willing to take oral

Bioavailability (BA)

The proportion of a drug that enters the circulation when it is introduced into the body and is available for action.

Physiological Challenges

Factors that affect the effectiveness of drug delivery in the rectal cavity, such as variability in absorption.

Ideal Physicochemical Properties

Characteristics that enhance drug absorption in rectal formulations, such as low molecular weight and specific log P values.

Retention Time

The duration a dosage form stays in the rectal cavity to ensure effective drug absorption.

Hemorrhoids

Swollen veins in the lower rectum or anus that can be treated with rectal medications.

Suppositories

Solid dosage forms intended for insertion into the rectum, where they dissolve and release medication.

Ointments and creams

Topical preparations that can be applied rectally for local effects.

Enemas

Liquid preparations administered rectally, often used for constipation relief or medication delivery.

pH Levels in Rectal Cavity

The optimal pH range for drug absorption in the rectum, typically between 7.0 and 8.0 in adults.

Patient Compliance

The degree to which a patient correctly follows medical advice regarding drug administration.

Aseptic Technique

A method that prevents contamination of the drug or device during administration.

Rectal Enemas

A type of rectal drug delivery that involves the administration of liquid through the rectum.

Cafergot® suppositories

Ergotamine tartrate and caffeine, used especially for treating migraines.

Physiological Barriers

Obstacles, such as blood flow and drug transport mechanisms, that impact drug delivery effectiveness.

Local

Hemorrhoids: pain, vasoconstrictors

Local Infection: antibiotics

Constipation: laxatives, enemas

Systemic

Patient is unresponsive: vomiting, seizing

Drug unstable in GIT

Drug irritates GIT

Disadvantages

• Variable Bioavailability: presence of feces

• Unpopular

• Low absorption rate

Ideal physicochemical properties: pKa at rectal pH

Suppository use

~1 inch in adults