Classification of Drugs

Question 1

Define a drug

Answer 1

A very broad definition of a drug would include all chemicals other than food that affect living processes.

Question 2

How can drugs be classified

Answer 2

Chemical structure
Pharmacological action
Pharmacodynamic agents
Sites of drug action
Drug-receptor interaction
Non-specific interactions

Question 3

What are Nitoimidazoles?

Answer 3

Nitroimidazoles are a class of antibiotics and antiprotozoal drugs characterized by a nitro group (–NO₂) attached to an imidazole ring. They are prodrugs, requiring activation under low-oxygen (anaerobic) conditions to exert their antimicrobial effects.

Question 4

Examples of Nitroimidazoles?

Answer 4

Metronidazole (Flagyl®)
Tinidazole (Fasigyn®)
Secnidazole
Ornidazole

Question 5

Nitroimidazoles are prodrugs activated only in anaerobic microbes. TRU/FALSE

Answer 5

TRUE

Question 6

Briefly explain the mechanism of action of Nitroimidazoles

Answer 6

Step 1: Activation in Anaerobic Conditions

Nitroimidazoles enter microbial cells by passive diffusion.

In anaerobic environments, microbial nitroreductase enzymes reduce the nitro group (–NO₂) to a cytotoxic nitro radical (–NO₂*⁻).

Step 2: DNA Damage & Cell Death
The nitro radical binds to DNA, causing strand breaks and inhibiting nucleic acid synthesis.

This leads to irreversible cell damage and death of susceptible organisms.

Question 7

Briefly explain 4-Aminoquinolones

Answer 7

4-Aminoquinolines are a class of synthetic ANTIMALARIAL drugs characterized by a quinoline ring with an amino group at the 4-position. The most important members are chloroquine and hydroxychloroquine.

Question 8

Give some examples of 4-Aminoquinolones

Answer 8

Chloroquine (Aralen®)
Hydroxychloroquine (Plaquenil®)
Amodiaquine
Piperaquine
Mefloquine

Question 9

Briefly explain the mechanism of action of 4-Aminoquinolones

Answer 9

> Drugs concentrate in acidic vesicles of Plasmodium
Prevent detoxification of toxic heme (ferriprotoporphyrin IX) into hemozoin
Toxic heme damages parasite membranes and proteins → death

Question 10

Briefly explain 8-Aminoquinolones

Answer 10

8-Aminoquinolines are a specialized class of antimalarial drugs that target the liver and sexual stages of Plasmodium parasites.

Question 11

Briefly explain 8-Aminoquinolones

Answer 11

Primaquine
Tafenoquine

Question 12

Examples of Quinolones

Answer 12

1st Gen > Nalidixic acid, Cinoxacin
2nd Gen > Ciprofloxacin, Ofloxacin, Norfloxacin
3rd Gen > Levofloxacin, Sparfloxacin
4th Gen > Moxifloxacin, Gemifloxacin

Question 13

Briefly explain the mechanism of action of Quinolones

Answer 13

Quinolones inhibit bacterial DNA synthesis by targeting:
>DNA gyrase (in Gram-negative bacteria) → prevents supercoiling.
>Topoisomerase IV (in Gram-positive bacteria) → blocks chromosome separation.
This leads to lethal DNA breaks and bacterial cell death.

Question 14

Give some examples of Sesquiterpenes

Answer 14

Artemether
Artesunate
Arteether
Dihydroartemisinin

Question 15

Give some examples of Sulphonamides

Answer 15

Cotrimoxazole
Pyrimethamine
Glucophage
Sulfadiazine
Sulfisoxazole
Sulfamethoxazole
Sulfadoxine

Question 16

Briefly explain the mechanism of action of Sulphonamides

Answer 16

> Sulphonamides mimic para-aminobenzoic acid (PABA), a substrate for bacterial dihydropteroate synthase (DHPS).

> They bind DHPS → block folate production.

Question 17

FUN FACT

Answer 17

Penicillins are a group of β-lactam antibiotics derived from the fungus Penicillium.

Question 18

Give some examples of Penicillins

Answer 18

Ampicillin
Cloxacillin
Cephalexin
Ceftriaxone
Ceftazidime
Cefotaxime
Penicillin G (IV)
Penicillin V (PO)
Ampicillin
Amoxicillin

Question 19

Briefly explain the mechanism of action of Penicillins

Answer 19

> Penicillins inhibit penicillin-binding proteins (PBPs), enzymes critical for peptidoglycan cross-linking.

> Without cross-links, bacteria lyse due to osmotic pressure.

> Active against rapidly dividing bacteria.

Question 20

Give some examples of Aminoglycosides

Answer 20

Gentamycin
Kanamycin
Streptomycin
Neomycin
Tobramycin
Amikacin

Question 21

Briefly explain the mechanism of action of Aminoglycosides

Answer 21

Aminoglycosides bind to the 30S subunit of bacterial ribosomes, interfering with protein synthesis. This causes:

> Misreading of mRNA, leading to faulty proteins

> Inhibition of protein elongation

The result is bacterial cell death—making aminoglycosides bactericidal.

Question 22

Aminoglycosides work on anaerobic bacteria TRUE/FALSE

Answer 22

FALSE

Only works against aerobic bacteria

Question 23

Give some examples of Macrolides

Answer 23

Erythromycine (1.5HRS)
Clarithromycin (5HRS)
Azithromycine (68HRS)

Question 24

Briefly explain the mechanism of action of Macrolides

Answer 24

Macrolides bind to the 50S subunit of bacterial ribosomes, inhibiting protein synthesis by blocking translocation of the growing peptide chain.

This action prevents bacterial growth

Question 25

Give some examples of Salicylates(class of NSAIDs)

Answer 25

Aspirin (acetylsalicylic acid) Mefenamic acid Ibuprofen Piroxicam Methyl salicylate Sodium salicylate Salicylic acid

Question 26

Briefly explain the mechanism of action of Salicylates

Answer 26

Salicylates, such as aspirin, irreversibly inhibit cyclooxygenase (COX) enzymes—specifically COX-1 and COX-2. This inhibition blocks the conversion of arachidonic acid to prostaglandins and thromboxanes, which are mediators of pain, fever, inflammation, and platelet aggregation.

Question 27

Give some examples of Opiates

Answer 27

Morphine codeine Heroin oxycodone hydrocodone Fentanyl methadone tramadol

Question 28

Briefly explain the mechanism of action of Opiates

Answer 28

Opiates bind to opioid receptors (mainly mu (μ), kappa (κ), and delta (δ)) in the central nervous system (CNS). This binding inhibits the transmission of pain signals by: >Decreasing neurotransmitter release >Reducing neuron excitability

Question 29

Give some examples of Benzodiazepine

Answer 29

Diazepam Alprazolam Lorazepam Clonazepam Midazolam Nitazepam Bromazepam

Question 30

Briefly explain the mechanism of action of Benzodiazepine

Answer 30

Benzodiazepines bind to a specific site on the GABA receptor in the central nervous system, enhancing the effect of GABA, the main inhibitory neurotransmitter. This leads to increased chloride ion influx, causing neuronal hyperpolarization and reduced excitability.

Question 31

Give some examples of Antacids

Answer 31

Aluminum hydroxide Magnesium hydroxide Calcium carbonate Sodium bicarbonate

Question 32

Give some examples of H2 - inhibitors

Answer 32

Cimetidine Ranitidine Famotidine Nizatidine

Question 33

Give some examples of Proton Pump Inhibitors

Answer 33

Omeprazole Esomeprazole Lansoprazole Pantoprazole Rabeprazole

Question 34

Give some examples of Gastrointestinal (GI) sedatives

Answer 34

Hyoscine Atropine Scopolamine Domperidone

Question 35

Give some examples of Laxatives and Purgatives

Answer 35

Bisacodyl Docusates Lactulose Senna

Question 36

Give some examples of Anthelmintics

Answer 36

Albendazole Mebendazole Levamisole Bephenium hydroxynaphthoate Pyrantel pamoate Praziquantel

Question 37

Briefly explain the mechanism of action of Anthelmintics

Answer 37

Albendazole/Mebendazole: Inhibit microtubule formation by binding to β-tubulin → disrupt glucose uptake → energy depletion.

Question 38

Give some examples of Antidiarrhoeals

Answer 38

Hyoscine Loperamide Diphenoxylate HCL