Drug tolerance

basic aspects of drug tolerance, basic pharmacological aspects of the topic are undertaken

1. DRUG TOLERANCE PRESENTATION BY: SAKSHI M. MANTRI 4 th SEM, B.PHARM, STUDENT SMT. BNB SWAMINARAYAN PHARMACY COLLEGE SALVAV,VAPI

2. ABOUT : It refers to the requirement of the higher dose of the drug to produce a given response. Loss of therapeutic efficacy ,which is a form of tolerance is often called “refractoriness”. Example:salfonyl ureas in type 2 diabetes. SMT BNB Swaminarayan Pharmacy college salvav,vapi

3. DRUG TOLERANCE TYPES : NATURAL TOLERANCE: The individual/species shows less sensitivity towards the drug due to inheritance. Example: rabbits are tolerant to atropine. Black race are tolerant to mydriatics . ACQUIRED TOLERANCE: This occurs due to repeated use of the drug in an individual who was initially responsive. Example: tolerance develops to barbiturates , opioids . SMT BNB Swaminarayan Pharmacy college salvav,vapi

4. Body is capable of developing tolerance to most drugs but the phenomenon is very easily recognized in the case of CNS depressants. An uninterrupted presence of the drug favours the development of tolerance. Tolerance may develop to some actions of the drug and not to the others. examples : SMT BNB Swaminarayan Pharmacy college salvav,vapi DRUG ACTION AFFECTED ACTION UNAFFECTED MORPHINE ANALGESIC & EUPHORIC CONSTIPATION & MIOTIC BARBITURATES SEDATIVE ANTIEPILEPTIC CHLORPROMAZINE SEDATION ANTI PSYCOTIC

5. MECHANISM OF TOLERANCE The mechanism of development of tolerance can be of two type: PHARMCOKINETIC/ DRUG DISPOSITON TOLERANCE PHARMACODYNAMIC/CELLULAR TOLERANCE SMT BNB Swaminarayan Pharmacy college salvav,vapi

6. PHARMCOKINETIC/ DRUG DISPOSITON TOLERANCE: Causes: Decreased effective concentration of the drug at target site Increased drug elimination Changes in drug absorption, distribution, metabolism. Example: barbiturates activate microsomal enzymes and enhance their own metabolism. Other examples: carbamazepine , amphetamine SMT BNB Swaminarayan Pharmacy college salvav,vapi

7. SMT BNB Swaminarayan Pharmacy college salvav,vapi PHARMCODYNAMIC /CELLULAR / FUNCTIONAL TOLERANCE: Causes: Decreased drug action Cells of target organ becomes less responsive as in morphine and barbiturates Example: response of antihypertensive is blunted due to salt and water retention. response of opioids is due to receptor down regulation.

8. CROSS TOLERANCE It is development of tolerance due to pharmacologically related drugs i.e., drugs belonging to a particular group. Example: alcoholics are relatively tolerant to barbiturates and general anesthetics Closer the two drugs are, more complete is the cross tolerance between them. Example: there is partial tolerance between morphine and barbiturates but complete tolerance between morphine and pethidine SMT BNB Swaminarayan Pharmacy college salvav,vapi

9. TACHYPHYLAXIS DRUG RESISTANCE It is rapid development of tolerance when doses of a drug repeated in quick succession resulting in marked reduction in drug response. Example: ephedrine, amphetamine, tyramine, nicotine and 5-hydroxytryptamine. It refers to tolerance of microorganisms to inhibitory action of antimicrobials. Example: staphylococci to penicillin SMT BNB Swaminarayan Pharmacy college salvav,vapi

10. REFERENCE: ESSENTIALS OF MEDICINAL PHARMACOLOGY,6 th edition, KD Tripathi, jaypee brothers medical publishers(P)LTD pg no.68 SMT BNB Swaminarayan Pharmacy college salvav,vapi MEDICAL PHARMACOLOGY,4 th edition, Padmaja udaykumar , CBS publishers & distributors pvt ltd, page no. 44

11. THANK YOU SMT BNB Swaminarayan Pharmacy college salvav,vapi