unit 1 general pharmacology

1. RECEPTORS AS A DRUG
TARGET
UNIT- 1 GENERAL PHARMACOLOGY (PC- 520)
PRIYANSHA SINGH
M.S. PHARM- PHARMACOLOGY & TOXICOLOGY (PC2021-14/226)
NIPER GUWAHATI

2. INTRODUCTION
DRUGS PRODUCE THEIR THERAPEUTIC EFFECTS BY PRODUCING BIOCHEMICAL/
PHYSICAL CHANGES: IN THE TARGET TISSUES OF THE HOST OR THE ORGANISMS
WHICH INVADE THE HOST.
THESE CHANGES ARE DUE TO PHYSICAL AND CHEMICAL PROPERTIES OF DRUG AND
THE ACTION ON THE DRUG TARGETS NAMELY;
▪ RECEPTORS
▪ ENZYMES
▪ CARRIER MOLECULES
▪ ION CHANNELS

3. INTRODUCTION
• TO GET DRUG ACTION, IT IS ESSENTIAL THAT:-
1. SUFFICIENT CONCENTRATION OF DRUG REACHES THE SITE OF ACTION
2. REMAINS THERE FOR A SUFFICIENT DURATION
3. THE TISSUE IS SUSCEPTIBLE FOR DRUG ACTION
• MAGNITUDE OF DRUG ACTION IS PROPORTIONAL TO THE CONCENTRATION OF
DRUG AT THE SITE OF ACTION.
• RECEPTOR MECHANISM IS VERY IMPORTANT TO UNDERSTAND THE ACTION AND
EFFECT OF A DRUG.

4. RECEPTORS
• COMPONENT OF A CELL OR ORGANISM WHICH INTERACTS WITH A DRUG AND
INITIATES THE CHAIN OF BIOCHEMICAL EVENTS THUS LEADING TO THE DRUG’S
OBSERVED EFFECTS
• THEY HAVE SPECIFIC BINDING SITES THAT ARE DEFINITE IN SIZE AND SHAPE
• MOST ARE PRESENT ON OR NEAR THE MEMBRANE.
• SOME LIE IN THE ENZYMES OR GENES
• PROTEIN (POLYPEPTIDE) IN NATURE

5. HISTORY OF RECEPTORS
• LANGLEY AND EHRLICH INTRODUCED CONCEPT OF RECEPTOR
• LANGLEY (1852 – 1925) STUDIED THE EFFECTS OF ATROPINE AGAINST PILOCARPINE
INDUCED SALIVATION IN CATS POSTULATED THAT THERE WAS A RECEPTIVE
SUBSTANCE IN THE NERVE ENDING OR GLAND CELL WITH WHICH BOTH ATROPINE
AND PILOCARPINE ARE CAPABLE OF FORMING COMPOUNDS.
• EHRLICH (1854 – 1915) OBSERVED THAT, CERTAIN DYESTUFFS ACTED SELECTIVELY,
STAINING SOME CELLS MORE DEEPLY OR IN A DIFFERENT WAY FROM OTHER CELLS
SUGGESTED THAT DRUGS WITH SELECTIVE ACTIONS ON PARTICULAR CELLS COULD
BE DEVELOPED INTRODUCED THE TERM “RECEPTOR”

6. SOME IMPORTANT TERMS RELATED TO
RECEPTORS

7. CONCEPT OF CELL SIGNALLING
Process in which cells sense the extracellular stimuli through membranous or intracellular
receptors, transduce the signals via intracellular molecules - Regulate the biological function of
the cells.

8. STRUCTURE AND FUNCTION OF RECEPTOR

9. OVERALL PROCESS OF RECEPTOR/ MESSENGER
ACTION

10. DRUG RECEPTOR INTERACTION

11. RECEPTOR OCCUPATION THEORY- CLARKE’S
THEORY

12. TWO STATE RECEPTOR MODEL

13. NATURE OF RECEPTORS & THEIR SUBTYPES

14. RECEPTOR SUBTYPES

15. RECEPTORS

16. RECEPTOR FAMILIES AND OTHER TYPES

17. DIAGRAMMATIC REPRESENTATION OF TYPES OF
RECEPTORS