Selective toxicity

Question 1

Selective toxicity

Answer 1

toxic effects to target cells (invading organisms or neoplastic cells) and not harmful to host cells
Differentiating through structural or functional differences

Question 2

Why do cytotoxic drugs tend to cause more harm to host cells than antimicorbials

Answer 2

Less structural differences between host and cancer cells

Question 3

what are the differences between host cells and bacteria

Answer 3

cell wall, cell membrane, bacterial DNA, NA, metabolic pathways

Question 4

Penicillin MOA

Answer 4

Cell wall inhibitors
Beta-lactam antibiotics - prevent cross-linking of the cell wall matrix – contains beta lactam ring substitutes for the peptidoglycan units – inhibiting the linking – causing cell wall distruction. Allows water and other substances to come in to burst.

Question 5

what are the two types of bacteria cell wall structure

Answer 5

gram +ve and gram -ve

Question 6

Penicillin

Answer 6

Beta lactam antibiotic

e.g. penicillins, cephalosporins, monobactums

Question 7

Which penicilling would be used to treat a staph aureus infection?

Answer 7

Flucloxacillin

Question 8

Why is clavulanic acid added to amoxicillin (e.g., Augmentin)?

Answer 8

Clavulanic acid was added to prevent the action of penicillinase, this avoided the issue with bacteria becoming resistant to amoxicillin.

Question 9

What is the mechanism of action of cyclophosphamide?

Answer 9

It is a pro-drug – non-toxic in its form but once it reaches the liver it is converted into active and toxic metabolites. Including phosphoramide mustard ‘alkylating agent’ – causes cytotoxic effects through combining with DNA in the cell nucleus and causes DNA intra-stand linking – preventing cell division and stopping replication of the cells and damages or kills cells.

Question 10

Why is it often given in combination with other cytotoxic agents, and why is it generally given in pulses?

Answer 10

The combination of other agents is to utilize the different mechanism of action and reduce toxic effect. Gain therapeutic effect without significant damage to cells. The treatment is given in cycles or pulses to allow host cells sufficient time to recover before the next dose is given.

Question 11

cyto-toxic drugs

Answer 11

toxic to cancer cells - particularly rapidly reproducing

also to host cells that rapidly reproduce - blood cells, mucous membranes