DRUG ABSORPTIONDr. Vaneet Aggarwal

P.G. In Pharmacology Department of Pharmacology

JJM Medical CollegeDavangere

DRUG ABSORPTION

1.Definition2.Biological Membrane

3.Mechanisms in Drug Transport 4.Drug Absorption through various

routes 5.Factors affecting drug absorption

6.Altering drug absorption 7.Bioavailability

BIOLOGICAL MEMBRANE

MECHANISMS IN DRUG TRANSPORT

• Transcellular transport

• Paracellular transport

• Vesicular transport

TRANSCELLULAR TRANSPORT

Passive transport 1.Passive Diffusion 2.Pore Transport

3.Ion Pair Transport4.Facilitated

Diffusion

Active Transport1.Primary active

transport 2.Secondary active

transporta)Symportb)Antiport

PASSIVE TRANSPORT

ACTIVE TRANSPORT

P-GLYCOPROTEINS

PARACELLULAR TRANSPORT

• Permeation between tight junction of epithelial cells

• Persorption

VESICULAR TRANSPORT

• Pinocytosis

• Phagocytosis

SUMMARY

DRUG ABSORPTION (PO)

DRUG ABSORPTION THROUGH VARIOUS ROUTES

Route Absorption mechanism Drugs delivered

sublingual Passive diffusion Antianginals like nitrites and nitrates

Anti hypertensives like nifedipine

Analgesics like morphine

Bronchodilators fenoterol

Rectal Passive diffusion Aspirin, paracetamol, theophylline.

Transdermal Passive diffusion Nitroglycerine, lidocaine scopolamine, testosterone, betamethasone .

Intramuscular Passive diffusion

Endocytosis

Pore transport

Phenytion, digoxin,

Several steroids

and antibiotics

Subcutaneous Passive diffusion Insulin, heparin.

Inhalational Passive diffusion

Pore transport

Salbutamol ,cromolyn, becolmethasone .

Intranasal Passive diffusion

Pore transport

Phenylpropanolamine,

Antihistamine.

Intraocular Passive diffusion Atropine, pilocarpine, adrenaline,

Antibiotics.

Vaginal Passive diffusion Steroidal drugs and contraceptive

metronidazole

FACTORS AFFECTING DRUG ABSORPTION

Pharmaceutical 1.Particle size2.Salt Form

3.Crystal Form 4.Hydrates

5.Nature of excipients and adjuvants 6.Drug pKa

7.Lipophilicity

Pharmacological1.Age

2.Gastric emptying 3.Intestinal transit

time4.Gastrointestinal pH

5.Disease state 6.Blood flow

7.Gastrointestinal contents

8.First pass metabolism

METHODS OF DELAYING ABSORPTION

• Appropriate dosage

• Physical characteristic

• Vasoconstrictor / tourniquet

METHODS OF FACILITATING DRUG

ABSORPTION

• Diffusion time

• Blood flow

BIOAVAILABILITY

"the rate and extent to which the active substance or active

moiety is absorbed from a pharmaceutical form of the drug

and is available at the site of action"

AREA UNDER THE CURVE

PARAMETERS • Cmax

• Tmax

• AUC

• Onset of action

• Duration of action

• Intensity

• MEC

• MSC

• MTC

• Therapeutic range

BIOAVAILABILITY

• Absolute

• Relative

• Bioequivalence

• Chemical equivalence

• Clinical equivalence

• Therapeutic equivalence

THANK YOU Have a nice day ahead !!