This document discusses multiple drug resistance (MDR) in several organisms and contexts. It begins with an introduction to MDR and its mechanisms, including enzymatic degradation, mutations, efflux pumps, and decreased membrane permeability. Specific examples of MDR are then explored in tuberculosis, bacteria, cancer cells, HIV, and malaria. The mechanisms of resistance and genes involved vary by organism but often involve efflux pump proteins like P-glycoprotein. MDR is an increasing public health issue due to its role in antibiotic resistance.

1. MULTIPLE DRUG
RESISTANCE
Shubhangi Gupta
M.Pharmacology
IInd
Sem, ISFCP

2. Introduction
History
Mechanisms of Multi drug resistance
Special Cases
 Multi drug resistance in TB
 MDR with Antibotics
 MDR in Cancer cells
 MDR in HIV infection
 MDR in Malaria

3. INTRODUCTION
 MDR is defined as the ability of a living cell to display
resistance to a wide spectrum of drugs that are not
structurally or functionally related.
 Organisms that display multidrug resistance can be
pathologic cells, including bacterial and neoplastic
(tumor) cells.
 MDR occurs in many situations such as the resistance
of :-
• Antibiotics
• Antifungal compounds
• Anticancer drugs
• Antiparasitic compounds

5. HISTORY
 The concept of multidrug resistance (MDR) in
tumours originated from the pioneer work of June
Biedler in the early 1970s, who identified a wide
profile of cross -resistance in Chinese hamster
cells selected for resistance to actinomycin D.
 The involvement of ABC proteins (P –
glycoprotein) was first identified and named by
Victor Ling in 1976, which is only the first of a
wide variety of membrane transporters involved
in many cellular functions and properties
including MDR.

6. MECHANISMS INVOLVED IN
MDR
Enzymatic degradation
Mutation at binding site
Down regulation of outer membrane
proteins
Efflux pumps

7. • Methicillin-Resistant Staph aureus (MRSA)
• Vancomycin Resistant Enterococci: (VRE)
• Extended Spectrum Beta-Lactamase
producing Enterobacteria. (ESBLs)

8. Enzymatic degradation
Mechanisms of b-lactamase
N
O
N
O
OH
S CH3
CH3
O
R
H
β-lactamase
CH2
OH
β-lactamase
CH2
OH
N
O
N
O
OH
S CH3
CH3
O
R
H
β-lactamase
CH2
O
H H2O
N
O
N
O
OH
S CH3
CH3
O
R
H
H
OH
β-lactamase
CH2
OH
+
Hydrolysis of Oxyimino group
Penicillin drug
Inactivated drug

9. Mutation at binding site
 In this binding of p53 to MDR1 is blocked at site(i.e. p53
DNA-binding site) and this mutation results in enhancement
of metastasis and mediate MDR

10. Down regulation of outer membrane
proteins
The outer membrane permeability is regulated by
porin proteins.
 Alteration in Outer membrane permeability
particularly due to the decreased expression of
porin
proteins results in decreased influx of various
drugs.
Additional resistance is also afforded by over-
expressed efflux pumps that extrude a wide variety of

11. EFFLUX PUMP
MDR is associated with increased expression of ABC
drug
transporter P-glycoprotein (P-gp)
 Pgp, the product of MDR1 gene is a membrane protein
consist of two duplicated halves each consist of
hydrophobic membrane spanning segments.
 Two close genes i.e. MDR1 and MDR3 are located at the
long arm of chromosome 7 that encodes Pgp(30)
MDR3 is not involved in drug resistance

12. contd…
Other proteins involved in MDR are :
•Multidrug resistance protein (MRP1)(encoded by ABCC1)
●MRP2(encoded by ABCC2)
●MRP3(encoded by ABCC3)
●MRP4(encoded by ABCC4)
●MRP5(encoded by ABCC5)
●Breast cancer resistance protein (BCRP encoded by
ABCG2)

13. SPECIFIC CASES

14. Multiple drug resistance in TB
MDR TB: MDR-TB caused by strains of Mycobacterium
tuberculosis which is resistant to both isoniazid and
rifampin
XDR TB: MDR + resistance to fluoroquinolone and 1 of
the 3 injectable drugs (amikacin, kanamycin,
capreomycin)
• Primary drug resistance:
– Infected with TB which is already drug
resistant
• Secondary (acquired) drug resistance:
– Drug resistance develops during treatment

15. Spontaneous mutations
develop as bacilli
proliferate to >108
Drug Mutation Rate
Rifampin 108
Isoniazid 106
Pyrazinamide 106

16. INH
RIF
PZA
INH
Drug-resistant mutants
in large bacterial
population
Multidrug therapy:
No bacteria resistant to all 3 drugs
Monotherapy: INH-resistant
bacteria proliferate

17. MECHANISM OF RESISTANCE IN
TB:
Rifampin
•Reduced binding to RNA polymerase
•Clusters of mutations at “Rifampin Resistance
determining Region” (RRDR)
•Reduced Cell wall permeability
INH
•Chromosomally mediated.
•Loss of catalase/peroxidase.
•Mutation in mycolic acid synthesis.

18. Gene location associated Drug-
Resistant M.tuberculosis
S.NO DRUG GENE
1 Isoniazid Kat G, Inh A, KasA
2 Rifampicin rpo B
3 Ethambutol emb B
4 Streptomycin rps L
5 Pyrazinamide pnc A
6 Fluoroquinolone gyr A

19. Bacterial resistance to
antibiotics
Bacterial Resistance to antibiotics occurs via
spontaneous mutation or by DNA transfer.
 Mechanisms involved in attaining
Multidrug resistance:
• Enzymatic deactivation .
• Decreased cell wall permeability.

20. Contd…
• Alteration in target sites.
• Increased efflux mechanisms.
• Increased mutation rate.
In addition, some resistant bacteria are able to
transfer copies of DNA that codes for a mechanism of
resistance to other bacteria, thereby conferring
resistance to their neighbours. This process is called
horizontal gene transfer.

22. Use antibiotics only for bacterial infections
Identify the causative organism if possible
 Use the right antibiotic; do not rely on broad-range
antibiotics
Not stop antibiotics as soon as symptoms improve;
finish the full course
Not use antibiotics for most colds, coughs, bronchitis,
sinus infections, and eye infections, which are caused
by viruses

23. Neoplastic resistance
Cancer cells also have the ability to become resistant to
multiple different drugs.
•Increased efflux of drug (as by P-glycoprotein, multidrug
resistance-associated protein, lung resistance-related protein,
breast cancer resistance protein and reproductive cancer
resistance protein)
Mechanisms involved are:
•Increased efflux of drug
•Enzymatic deactivation (i.e, glutathione conjugation)
•Decreased permeability (drugs cannot enter the cell)
•Alteration in binding sites
•Development of alternative metabolic pathways

24. The drug resistance that develops in cancer cells often
results from elevated expression of particular proteins,
such as cell-membrane transporters, which can result in
an increased efflux of the cytotoxic drugs from the
cancer cells, thus lowering their intracellular
concentrations.
The cytotoxic drugs that are most frequently associated
with MDR are hydrophobic, natural products, such as
the taxanes (paclitaxel, docetaxel), vinca alkaloids
( vincristine, vinblastine), anthracyclines (doxorubicin,
daunorubicin, epirubicin), epipodophyllotoxins
(etoposide, tenipo-side), topotecan, dactinomycin, and
mitomycin.

27. Multiple drug resistance in HIV

28. NDM-1 is a Metallo Beta-Lactamase essentially found in
Enterobacteriaceae (principally E. coli and K.
pneumoniae).
 NDM-1 stands for New Delhi Metallo-beta-lactamase-1,
since it was first identified in a Swedish patient of Indian
origin, who had been admitted to hospital in New Delhi,
India in 2008. The NDM-1 gene makes bacteria resistant to
fluroquinolones, aminoglycosides and almost all beta-
lactams including carbapenems (imipenem, meropenem,
ertapenem, doripenem).
The gene for NDM-1 is found on plasmids (DNA strands),
which can easily spread from one strain of bacteria to
another

29. MULTIPLE DRUG RESISTANCE
IN MALARIA
Resistance developed due to the decreased
ability of the parasite to accumulate the drug .
MDR -1 gene is associated with the resistance
in malaria.
So the modulators , for eg- verapamil :-
restored the concentration drugs which causes

30. MultiDrugQuant Assay Kit
The kit provides a fast, simple and reliable ,and quantitative
method for measuring the drug transport activity of the
clinically most important multidrug resistance proteins : MDR1
(p-gp) and MRP1.
It was developed as a flow cytometric assay, where intracellular
calcein fluorescence is measured after incubating the cells with
the dye acetoxymethylester form of fluorescent calcein (calcein-
AM) in the presence and absence of inhibitors of Pgp and MRP1.
 Intracellular fluorescence intensities obtained with or without
inhibitors are used for calculation of MDR activity factor (MAF)
values, which are the quantitative measures of transport activity
of Pgp and MRP1.