FIRST ORDER RELEASE

APPROXIMATION

Introduction Modified drug release dosage

forms:These dosage forms are designed

to release drugs in a controlled manner, at a predetermined rate, duration and location to achieve and maintain optimum therapeutic levels of drug.

terms used to describe modified release

dosage forms sustained release (SR) prolonged action controlled release (CR) extended release (ER) modified release timed release long acting

drugs suited for modified release

productsDrugs that have neither very

slow nor very fast rates of absorption and excretion

Drugs that have uniform absorption in the GI tract

Drugs that have small doses (less than 500mg)

Drugs with a wide therapeutic index

Drugs for chronic disease conditions

Drug release kinetics

• First-order kinetics

• Zero-order kinetics

ZERO-OREDER KINETICS

• The process that takes place at a

constant rate independent of drug

concentration involved in process

• Rate of process cannot be increased even the drug concentration is increased

First-order kinetics

• The process that is directly proportional to the drug concentration involved in

process • Rate of process

increases linearly with increase in drug concentration

First order release approximation

• Biopharmaceutical factors

• Dosage form selection

Biopharmaceutical factors

• Stomach• Small intestine• Large intestine

Stomach

• Dissolution of drug in stomach may be affected by presence or absence of food

Small intestine• Basic pH, large surface

area and presence of bacterial flora may affect the absorption of drug

Large intestine• Not much is known about drug

absorption in this area although unabsorbed drug that reaches the area are metabolized by bacteria.

Dosage form selection

• To minimize risk of rapid stomach absorption

• To release the drug immediately

Group members

Ambreen Ghulam Nabi 2910130

Ishima Naiyarain Zafar 2910171

Komal Sandhu 2910176

Maryam Musharraf 2910185

Sobana Baree 2910233

Syeda Zehra Jabeen Naqvi 2910245

Syeda Midhat Fatima 2910246

Samia Yaqoob 29478