Chapter 7 anti infective - antiparasitic therapy

Question 1

metronidazole (flagyl)

Answer 1

• activated nitro intermediates bind DNA and inhibit anaerobe replication
• antiparasitic mech unknown..

indication
* protozoans:
1) entamoeba (intestinal and extraintestinal infections.)
2) histolytica (same as above w/ diarrhea (loose stool/poop), nausea (a feeling of sickness in the stomach), and weight loss.)
3) trichomonas (common sexually transmitted infection caused by a parasite. In women, trichomoniasis can cause a foul-smelling vaginal discharge, genital itching and painful urination. Men who have trichomoniasis typically have no symptoms.)
4) giardia (iny parasite (germ) that causes the diarrheal disease giardiasis. Giardia is found on surfaces or in soil, food, or water that has been contaminated with feces (poop) from infected people or animals.)
* anaerobes
1) bacetroides
2) clostridium
3) peptococcus

effects
* sz
* ataxia
* dizziness
* disulfiram like rxn – adverse reaction to alcohol leading to nausea, vomiting, flushing, dizziness, throbbing headache, chest and abdominal discomfort, and general hangover-like symptoms among others.

Question 1

Lindane (kwell for e.g)

Answer 1

Induce sz in ectoparasites (outside host)

indication
* scabies (body, head, pubic louse)
* pediculus capitis — head lice
* p corporis — body lice
* htirus pubus – pubic crab… ew

effects
* topical administration — may l/t sz
* CNS disturbances + risk of arrhytmias as well
* overall skin irritant

Question 2

Mebendazole

antihelminthic drugs

Answer 2

• ldisrupts microtubules in worms

indication
* pinworms
* roundworms

effects
* diarrhea
* fever
* highly contagious — family member should be tx’d

Question 3

praziquantel

Answer 3

• inc cell membrane permeability l/t loss of intracellular Ca++
• l/t paralysis of worms and release from host tissues

\indication
* schistosome infection (parasitic flatworms)
* single dose adequate

effects
* pt may feel like they have flu

Question 4

thiabendazole

antihelminthic drug

Answer 4

unknown mech

indication
* strongyloidasis (disease caused by a nematode, or a roundworm, in the genus Strongyloides.)
* multiple parasitic infection

effects
* flu sx
* hepatotoxicity
* CNS disturb
* anorexia

Question 5

ivermectin (stromectol)

antihelminthic

Answer 5

helminthic glutamate-gated channel antagonist antagonist cause worm paralysis

indication
* strongyloides (nematodes, or roundworms)
* onchocerca (A parasitic, tropical disease that affects the skin and eyes.
The disease is spread by repeated bites from infected black flies. It’s most common in those who live in remote African villages. —- river blindness)

effects:
* pruitus
* fever in onchoerciasis patients

Question 6

cloroquine hydroxychloroquine (plaquenil)

antimalarial

Answer 6

• 4-aminoquinoline – mechanism unknown

indication
* prophylaxis or acute forms
* erythrocytic forms (A stage in the life cycle of the malaria parasite found in the red blood cells. Erythrocytic stage parasites cause the symptoms of malaria.) of p. falciparum (unicellular protozoan parasite of humans, and the deadliest species of Plasmodium that causes malaria in humans.)
* some autoimmune disease
1) lupus
2) rheumatoid arthritis

effects
* irreversible retinal damage
* impaired accommodation
* bullseye retina
* hemolysis in g6PD deficient patients (when the body doesn’t have enough of an enzyme called G6PD (glucose-6-phosphate dehydrogenase). This enzyme helps red blood cells work correctly. A lack of this enzyme can cause hemolytic anemia.)

Question 7

quinine

antimalarial

Answer 7

• increasing resistance in SE asia… unknown mech

inidcation
* chloroquine resistant P. falciparum
* little effect on sporozoites (motile spore-like stage in the life cycle of some parasitic sporozoans (e.g. the malaria organism), ) or pre-erythrocytic stages

effects
* most toxic antimalarial — last resort
* cinchonism (cluster of dose-related and reversible side effects of quinine, including tinnitus, decreased hearing, headache, nausea, vomiting, dysphoria and visual disturbances.)
* curare-like effects (Gradual paralysis of limbs, followed by paralysis of respiratory muscles and death from asphyxia)
* shock

Question 8

mefloquine

antimalarial

Answer 8

• structural analog of quinine

indication
* active against multirug resistant malaria (including chloroquine resistant P. falciparium)

effect
* well tolerated
* benign sinus bradycardia
* single dose cures multidrug resistant p. alciparum malaria

Question 9

pyrimethamine

antimalarial

Answer 9

• inhibits folate synthesis (interfree w/ dihydrofolate reductase)
• less resistance when used in combination (w/ sulfonamides — fansidar [market])

indication
* malaria prophylaxis
* erthrocytic form of p. falciparum
* used in combination with sulfonamides or sulfones for ACUTE attacks
* combined with sulfadiazine for treating toxoplasmosis (infection with a parasite called Toxoplasma gondii. People often get the infection from eating undercooked meat. You can also get it from contact with cat feces.)

effects
* few mild side effects

Question 10

primaquine

antimalarial

Answer 10

• mech unclear
• crosslinking with glutathione (antioxidant)
• little resistance d/t p. vivax (Plasmodium vivax is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring malaria.)

indication
* chlorquine resistant vivax malarias
* more active against hepatic than erhtrocytic forms of malaria

effects
* hemolysis in patients with G6PD (when the body doesn’t have enough of an enzyme called G6PD (glucose-6-phosphate dehydrogenase). This enzyme helps red blood cells work correctly. A lack of this enzyme can cause hemolytic anemia.)