Chemotherapeutics

Question 1

Chemotherapeutics classification

Answer 1

1. Anti-microbial drugs (Antibacterial [not antibiotics], antifungal,antiviral)
2. Anti-neoplastic agents
3. Anti-parasitic agents (antiprotozoal , endoparasiticidal, ectoparasiticidal)

Question 2

Unique target drugs

Answer 2

1. Cell wall synthesis inhibition: B-lactamase, glycopeptides , bacitracin
2. Fungal cell membrane components: Ergosterol
   *Ergosterol synthesis inhibitors (azoles)
   *Ergosterol- complex formers (polienes)
3. Folic acid synthesis: (PABA=>dihydrofolic acid)
   Dihydropteroate-synthase
   (sulphonamides= PABA structural analogues)

Question 3

Similar target drugs

Answer 3

1. Dihydrofolate reductase inhibition: Trimethoprim
2. Protein synthesis inhibitors:
   * 30S ribosomal subunit: aminoglycosides (most toxic)
   * 50S: phenicols (dose dependent toxicity)

Question 4

Common target

Answer 4

1. Primary antineoplastic agens: cell division inhibitors
   [Not in intestinal mucosa or bone marrow]
2. Anti-parasitic drugs: cholinergic substances (organophosphate)
3. Anti-bacterial drugs

Question 5

Bacteriocidal drugs

Answer 5

Penicillins, Cefalosporins, AMINOGLYCOSIDES, POLYPEPTIDES, potentiated SA , FLUROQUINOLONES, metronidazole

Question 6

Bacteriostatic

Answer 6

Tetracycline,macrolides, lincosamides , pleuromutilins, phenicols

Question 7

Combinations

Answer 7

1. Bacteriocidal-bacteriostatic

2. Additive-synergistic-antagonist

Question 8

Synergistic combination example

Answer 8

1. Penicillin+ streptomycin

2. lincomycin+ spectinomycin

Question 9

Synergistic combination example

Answer 9

1. Penicillin+ streptomycin

2. lincomycin+ spectinomycin

Question 10

Additive combination example

Answer 10

Gentamicin+metronidazole

Question 11

Antagonist combination example

Answer 11

Erythromycin+ chloramphenicol

Question 12

Resistance mechanism

Answer 12

1. Antibiotic degrading enzymes: penicillase
2. Antibiotic transforming enzymes: (aminoglycosides- acylation,adenylation)
3. Increasing integrity of cell wall
4. Increased efflux pump expression
5. Modifying binding sites ( fluroquinolones)

Question 13

Category B - restrict Antibiotics?

Answer 13

most frequently used, fluoroquinones, colistins and 3-4th generation of cephalosporines.

Question 14

which concentration of antibiotic in the body would you like to achieve?

Answer 14

Above MPC (minimum prevention conc. -  above the mutant selection window - both suseptible and mutant bacteria are dead )
 *ideally: MBC (minumum bacterial conc.) - hard to achieve