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.