L 23-24 Antibacterial drugs Antiprotozol Antifungal drugs→↑↓

Question 1

Name of Anti bacterial Type

for Cell Wall synthesis and MoA

Answer 1

Beta -lactam
→Penicillins
→Cephalosporins

Non-beta lactam
→Vancomycin
→Bacitracin

MoA : interfere with cell wall peptidoglycan synthesis by inhibiting enzymes in the peptide cross-linking step, →→compromising cell wall structural integrity, esp for Gram +ve bacteria.

Question 2

Name of Anti bacterial Type

for Cell Membrane Permeability and MoA

Answer 2

Polymyxins

→attach to cell membrane →→ disrupt the membrane permeability

Question 3

Name of Anti bacterial Type Inhibit protein synthesis and MoA

Answer 3

Inhibit the function of Bacterial ribosomes 30S subunit
→Tetracyclines
→Aminoglycosides

Inhibit the function of Bacterial ribosomes 50S
→Chloramphenicol
→Macrolides

Question 4

Name of Anti bacterial Inhibits folate synthesis and MoA

Answer 4

Sulfonamides
→inhibit dihydropteroate
synthetase

Trimethoprim:
→inhibit
dihydrofolate reductase

MOA: these drugs are structurally similar to folate
intermediates of DNA synthesis,
→they compete with the folate intermediates and inhibits DNA synthesis

Bacteriostatic
→suppresses division of bacteria, but does not
kill them

Question 5

Name of Anti bacterial Inhibit nucleic acid synthesis and MoA

Answer 5

Inhibit DNA synthesis
Metronidazole
→ taken up by diffusion & metabolized 
→→forms unstable molecule with DNA (DNA breaks),
→→→inhibiting DNA synthesis
Quinolones

Inhibit RNA synthesis
Rifampin

Question 6

Name of Drug for Intestinal Amoebiasis and MoA

Answer 6

Iodoquinol
→Acts against active amoebae (trophozoites) in the intestinal lumen

→The exact MOA is unknown.

Often given in combination with tissue amoebicide

Question 7

Name of Drug for Tissue Amoebiasis and MoA

Answer 7

Chloroquine

Treatment is usually combined with an intestine amoebicide

Question 8

Name of Drug for intestinal and extra-intestinal amoebiasis and MoA

Answer 8

Metronidazole

intracellularly reduce
metronidazole 
→→ active form
→→→ covalently binds to DNA
→→→→ inhibits DNA synthesis

Question 9

Name of Drugs for malaria and MoA Quinine and related compound

Answer 9

Natural product:
→ Quinine
MoA: Prevention of hemozoin formation by inhibiting heme polymerase

Synthetic drugs:
→Chloroquine (Effective against erythrocytic forms)
MoA: Bind to heme to form heme-chloroquine complex
→→ caps hemozoin molecules to prevent further biocrystallization of heme
→→ toxic to cell, distrupt membrane function and cell lysis

→Mefloquine (For chloroquine-resistant strains)
MoA: Not known, probably inhibiting heme polymerase leading to inhibition of hemozoin formation

→Primaquine Effective against erythrocytic (Blood) forms or exoerythrocytic forms
MOA : unclear, interferes with
mitochondrial electron transport in parasites

Question 10

Name of Drugs for malaria and MoA Antifolate combination drug

Answer 10

Dihydrofolatereductase inhibitors:
Trimethoprim
Proguanil
Pyrimethamine

Sulfa drugs:
Sulfalene
Sulfamethoxazole

MoA: 
→Inhibit folate formation, an
essential nutrient required by
parasites, folate is a precursor of purine, the DNA building
block, inhibit growth and
proliferation

Antifolate combination drug
Metakelfin
→sulfalene/ pyrimethamine
Co-trimoxazole
→sulfamethoxazole-trimethoprim

Question 11

Name of Drugs for malaria and MoA Antibiotics

Answer 11

Tetracycline

Doxycycline

MOA: Inhibit protein synthesis by binding reversibly to 30s subunit

Tetracycline + quinine → improve cure rate

Question 12

Name of Drugs for malaria and MoA Antibiotics Artemisinin compounds

Answer 12

Artemisinin (from Artemisia annua)

MOA: Largely unknown;
→ radical formation that depends on their endoperoxide bridge
→ Artemisinins + heme → artemisinin-heme adduct
Artemisinin-heme adduct
→ → inhibits heme polymerization and hemozoin formation

→ Artemisinins also promote breakdown of hemozoin

Combination therapy with antimalarials
→Artesunate + sulfadoxine/pyrimethamine
→Artesunate + Mefloquine

Question 13

Name of Drugs for malaria and MoA Miscellaneous compounds

Answer 13

Halofantrine

MOA: Unclear
inhibit polymerisation of
heme molecules

Halofantrine has been
shown to bind and
inhibit plasmpesin, a
hemoglobin degrading
enzyme

Atovaquone
MOA: 
→inhibits electron transport at the cytochrome
bc1 complex
→→blocking ATP and pyrimidine
biosynthesis

Effective against chloroquine-resistant P. falciparum

Question 14

Name of antifungal drugs and MoA

Polyenes

Answer 14

Amphotericin B
→Binds to ergosterol
→→Forms holes in the
membranes
→→→Causing leakage of
the fungal cell
content
→→→→Lysis of the cell. 

S/E affect cholesterol in human cell membranes
and confer to its toxicity.

Nystatin
No drug-drug interactions.
→Binds to ergosterol
→→Forms holes in the
membranes
→→→Causing leakage of
the fungal cell
content
→→→→Lysis of the cell.

Question 15

Name of antifungal drugs and MoA Terbinafine

Answer 15

Terbinafine

MoA
→Inhibit the enzyme squalene epoxidase needed for synthesis of ergosterol.
→Causing a defective cell membrane, leading to cell lysis.

Question 16

Name of antifungal drugs and MoA Azoles

Answer 16

Mechanism of action:
→Bind to Lanosterol 14 α-demethylase that is required for synthesis of ergosterol.

Ketoconazole

Fluconazole
→Contraindicated during pregnancy
→→cause fetal malformations.

Itraconazole
→Contraindicated for patients with congestive heart failure.

Question 17

Name of antifungal drugs and MoA Echinocandins

Answer 17

Caspofungin

MoA
→Prevents cell from making
beta-glucan by blocking
beta-(1,3)-D-glucan
synthetase.
→Disrupt fungal cell wall
→Leakage of cellular content and thus cell lysis.
→Human cells do not contain cell wall, these drugs are less toxic than polyenes and azoles.

Question 18

Name of antifungal drugs and MoA Flucytosine

Answer 18

Flucytosine (pro-drug)
MoA blocks DNA and RNA synthesis

5-fluorouracil (active drug) converted in fungal cells

MoA : goes to channel becomes 5FU →5FUMP→→ 5FUDP→→→5FUTP →→→→ block RNA synthesis

5FUMP→5FdUMP( a potent inhibitior of thymidylate synthetase a critical sources of thymidine → inhibition of DNA synthesis

Question 19

Name of antifungal drugs and MoA Griseofulvin

Answer 19

MoA : binds to tubulin, interfering with microtubule function and thus inhibit mitosis.

Question 20

Name of antibiotics and MoA for PCP in AIDS

Answer 20

Trimethoprim/
sulfamethoxazole
(TMP/SMX; cotrimoxazole)

MoA
TMP blocks DHFR
SMX belongs to
sulfonamides, which are
derivatives of PABA that
blocks DHPS 

Folate is important for DNA/RNA synthesis, and
therefore stopped their growth

• P.S. Dapsone + TMP can also be used to treat PCP