Antiparasites

Question 1

Malaria and its treatments

Answer 1

Caused by the parasite plasmodium protozoa. Infects liver, then blood, then gametocytes.

Quinine, chloroquine, and artemisinin have been used to treat it

Quinine has unclear mechanism of action. May interfere with parasite ability to utilise haemoglobin, or inhibits purine nucleoside phosphorylase (deficiency in DNA/RNA)

Chloroquinine prevents heme cristallisation from haemoglobin. This leads to lysis (death from cell wall degradation) of the cell. Resistance can develop from chloroquine resistant transporter.

Artemisinin is a prodrug. unclear mechanism. produces free radicals (that damage parasite) upon reacting with free heme. Binds many other targets, acting on the parasite in other stages of its life cycle.

Question 2

Clotrimazole and Flucanazole

Answer 2

treats yeast infections, or fluconazole which treats other fungal

Inhibits fungal CYP enzyme 14alpha-demethylase, to prevent the conversion of lanosterol to ergosterol -> inhibits synthesis of membrane lipids, leading to altered cell wall permeability

Question 3

Terbinafine

Answer 3

For athletes foot

Inhibits squalene epoxide to inhibit squalene to lanosterol reaction.

this inhibit the downstream ergosterol synthesis (lanosterol converted to ergosterol)

Question 4

Resistance in anti parasitic treatment

Answer 4

Efflux pumps can evolve, to decrease the amount of drug that enters the cell. Can render treatment useless. Modifying enzymes can also develop, which make the treatment pharmacologically ineffective

Question 5

Parasitic worms treatments

Answer 5

Mebendazole and albendazole are tubulin inhibitors that block the polymerisation of tubulin. Leads to cell death.

nAChR and GluCl ion channel agonists can cause paralysis in worms. Agonists include levamisole, pyrantel, morantel (nAChR), and ivermectin + doramectin (GluCl)

Praziquantel causes a Ca influx that leads to paralysis of the worm, through an unknown mechanism