A Presentation on-

CARRIER MADIATED TRANSPORT

Submitted by –

KULDIP DEKAROLL NO : 19

B.PHARM 4TH YEARDEPARTMENT OF PHARMACEUTICAL SCIENCES

DIBRUGARH UNIVERSITY

Carrier mediated transport:

Movement which occurs across membrane, such as blood-brain barrier and GIT mucosa.

The passage of glucose, amino acids, and other polar molecules through the cell membrane is mediated by carrier proteins in the cell membrane.

Carrier-mediated transport exhibits the properties of specificity, competition, and saturation. The transport rate of molecules such as glucose reaches a maximum when the carriers are saturated.

In case of drug-If the drug is lipophilic drug may

pass through the cell or go around it. If the drug has a low molecular

weight and is lipophilic, the lipid cell membrane is not a barrier to drug diffusion and absorption.

In the intestine, drugs and other molecules can go through the intestinal epithelial cells by either diffusion or a carrier-mediated mechanism.

Types of carrier mediated transport-

1.Active Transport2.Passive diffusion3.Facilitated diffusion4.Vesicular Transport5.Carrier mediated intestinal transport

6.Ion pair formation

1] ACTIVE TRANSPORT: Transport method that moves particles from an area of low concentration to an area of high concentration or against a concentration gradient. It is an energy-consuming Process, energy obtained from ATP in active transport can be direct or indirect. Direct use of ATP is called primary active transport, and indirect use is called secondary active transport.

Primary active carrier mechanism

• Primary Active Transport of the sodium/potassium (Na+ /K+) pump in nerve cells

Secondary active transport:Use an electrochemical gradient as a source

of energy to transport molecules or ions across a cell membrane

• In this type of active transport, the energy to pump 1 solute is derived from the downhill movement of another solute.These are of 2 types:

• 1. Symport: when the concentration gradient are such that both the solutes move in same direction.

• Eg-Na+/neurotransmitter co-transporters)• 2. Antiport: when the concentration gradient are

such that both the solute move in opposite direction

• Eg-Na,Ca exchangers

2] Passive diffusionDrug molecules transport from High conc. to low conc. Passive transport is a movement of biochemicals and other atomic or molecular substances across membranes. Unlike active transport, it does not require an input of chemical energy, being driven by the growth of entropy of the system. The rate of passive transport depends on the semi-permeability of the cell membrane, which, in turn, depends on the organization and characteristics of the membrane lipids and proteins. The four main kinds of passive transport are diffusion, facilitated diffusion, filtration and osmosis.

Active Transport & Passive Transport

Facilitated diffusion is the process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins,differing from active transport in that the drug moves along a concentration gradient Therefore, this system does not require energy input.

3] Facilitated diffusion:

Example: entry of glucose into muscle and fat cells by GLUT4

4] Carrier mediated intestinal transport

Various carrier-mediated systems (transporters) are present at the intestinal brush border and basolateral membrane for the absorption of specific ions and nutrients essential for the body. Many drugs are absorbed by these carriers because of the structural similarity to natural substrates. A transmembrane protein, P-glycoprotein (Pgp), has been identified in the intestine.

Intestine Transporters and Examples of Drugs Transported

5] Vesicular transport:

Vesicular transport is the process of engulfing particles or dissolved materials by the cell. Pinocytosis refers to the engulfment of small solutes or fluid, whereas phagocytosis refers to the engulfment of larger particles or macromolecules, generally by macrophages. Endocytosis and exocytosis are the processes of moving specific macromolecules into and out of a cell, respectively.

6] Ion-pair formation :

Highly ionized or charged molecules, such as quaternary nitrogen compounds and sulphonic acid transport in this process. These drugs penetrate by linked up with an oppositely charged endogenous ions like mucin, an ion pair is formed in which the overall charge is neutral. This neutral complex diffuses more easily across the membrane.

For example, In case of propranolol, a basic drug that forms an ion pair with oleic acid.

THANK YOU

REFERENCES:•http://www.pharmacorama.com/en/Sections/NAK-ATPase-Digoxin.php•Applied biopharmaceutics and pharmacokinetics,5th edition by Leon Shargel,, Susanna Wu Pong, Andrew B.C. YU,PUBLISHER:MC GRAW HILL’S•Essentials of medical pharmacology ,6th edition k.d tripathi.page no.13-15•https://www.boundless.com/biology/textbooks/boundless-biology-textbook/structure-and-function-of-plasma-membranes-5/active-transport-66/primary-active-transport-337-11474/•http://www.mhhe.com/biosci/ap/foxhumphys/student/olc/chap06summary.html