Anti-parasitics Flashcards
The treatment goal for protozoa is ___________, while the treatment goal for helminths is ___________.
- Eradication
- Eradication or reduction
Protozoa: complete replication w/in definitive host; illness results from single exposure.
Helminths: life-cycle involves more than definitive host; repeated exposures necessary for disease.
What’s the difference b/w definitive host, intermediate host, and incidental host?
- Definitive: harbors sexual parasitic stage
- Intermediate: harbors larval or asexual stage
- Incidental host: not necessary for parasitic infection
What’s the difference b/w gametogony and schizogeny?
- Gametogony: sexual development
- Schizogeny: asexual development
Where would you use chloroquine, and for what reason?
Only in areas w/o resistant Plasmodium falciparum (for prevention).
*Name the 2 best treatments for malarial prevention.
- Mefloquine
- Atovaquine + proguanil
In areas of high multi-drug resistance, what drug would you give to prevent malaria?
Doxycycline
For terminal prophylaxis vs. Plasmodium vivax and ovale, what drug would you use?
In what pt population would you avoid using this?
Primaquine
Avoid in G6PD deficiency pts, pregnancy, and granulocytopenics (children ‘okay’)
Assuming no resistance, what’s the preferred drug to treat P. falciparum malaria?
Chloroquine
What drug combo would you use to treat P. vivax and ovale infections?
Primaquine (w/chloroquine)
What defines a “complicated” malarial infection? (not sure if it will be tested)
*Complicated or severe malaria is defined as coma or severely AMS, hypoglycemia, renal failure, parasitemia > 5%, seizures other than 1 short febrile seizure, respiratory distress, shock, etc.
Name the LUMINAL agents used in the treatment of amoebiasis.
What should you add if there is colitis or liver abscess?
- Iodoquinol
- Paromomycin
- Diloxanide furoate
Add metronidazole
What substance does an amoebic liver abscess resemble?
Anchovy paste
What are the 2 primary tx agents for giardiasis?
What are 2 alternates?
Primary: metronidazole, nitazoxanide
Alternate: furazolidone, albendazole
What’s an important management principle in treating cryptosporidiosis w/HIV?
What’s the DOC?
What are some other agents?
Restoration of immune response
DOC: Nitazoxanide (even in moderately immunosuppressed)
Others: Paromomycin, (azithromycin, clarithromycin)
What’s the DOC combo for toxoplasmosis?
Pyramethamine + sulfadiazine/clindamycin
What are the 2 broad categories of leishmaniasis?
Visceral and cutaneous
What’s the mainstay for tx of Leishmaniasis?
What else can be used?
Na+ Stibogluconate
- Amphotericin B, liposomal amphotericin B, miltefosine
What’s the DOC for AFRICAN trypanosomiasis?
What are some other options?
- Suramin (crosses BBB)
- Alt’s: Pentamidine, melarsoprol, eflonithine
What’s the DOC for AMERICAN trypanosomiasis?
What’s another option?
- Nifurtimox
- Alt: benznidazole
What bug causes Chagas dz?
T. cruzi (American trypanosomiasis)
What diseases have parasites w/ kinetoplasts?
Chagas disease, leishmaniasis, and sleeping sickness
there is a new drug that targets these. prob not on test
What is the DOC for neurocystocercosis?
Albendazole
What’s the DOC for filariasis?
Diethylcarbamazine
What the DOC for onchocerciasis?
Ivermectin
What the DOC for strongyloidiasis?
Ivermectin
What is the major side effect of sodium phosphate?
Acute phosphate nephropathy
Risk factors for nephropathy: old age, renal insufficiency, V depletion, meds (ACEIs/ARBs)
Contraindications for Mg citrate and Mg OH?
Bowel obstruction, renal failure
Which osmotic laxative is used for surgery prep?
Polyethylene glycol
What agent should you prescribe to PREVENT the formation of hard stool?
Docusate (detergent/surfactant/stool-softener)
Glycerin suppositories/enemas would also work, but she calls it a lubricant
Why should mineral oil (a lubricant) never be administered orally to sick/debilitated pts?
Lipoid pneumonitis
Name the other stimulant laxative we learned about besides senna.
Bisacodyl (unlike senna, doesn’t cause melanosis coli)
Miralax is a smaller dosed version of what?
Polyethylene glycol
What are the possible side effects of magnesium-based osmotic laxatives?
Dehydration, electrolyte abnormalities, ischemic colitis
What’s the name of the H1 receptor blocker that we should know for the exam?
- What’s it’s main side-effect?
- Promethazine
- Sedation
(also includes diphenhydramine, meclizine)
What is the full MoA for metoclopramide? (2 things)
1) Dopamine receptor antagonist (CTZ/area prostrema).
2) Dopamine receptors inhibit cholinergic smooth muscle stimulation, blockade of this effect = primary prokinetic action, promiting motility of the upper GI tract (increasing pressure in lower esophageal sphincter and increasing gastric emptying)”
What is the MoA for prochlorperazine?
Central dopamine receptor antagonist in chemorecetpor trigger zone (CTZ) AKA area prostrema. May peripherally block vagus n.
What is torticullis?
What med is it a SE of?
Torticollis is a condition in which the neck muscles cause the head to turn or rotate to the side.
- Prochlorperazine
Name 2 corticosteroids that can be used as anti-emetics.
*When would they be indicated?
- Prednisone
- Dexamethasone
*Indicated in nausea due to increased intracranial pressure
Dronabinol: MoA?
(Purified synthetic delta-9-tetrahydrocannabinol)
- Cannabinoid receptor (CB1) agonist. CB1 receptors located throughout CNS.
Dronabinol: indications?
Breakthrough chemo-induced N/V (ie last resort).
Dronabinol: toxicity?
Euphoria, dysphoria, paranoid delusions, cognitive clouding, somnolence, sedation, hypotension.
(Effectiveness: Greater than placebo, similar to phenothiazines.
5HT3 receptor antagonists have greater potency than CB1 agonists.
Narrow therapeutic window.)
When is prochlorperazine indicated?
What are it’s side effects similar to?
Opioid-related N/V; GI disorders (inflammation/infection, ie gastroenteritis…may block vagal n to CNS)
Side effects similar to metoclopromide
What anti-malarias have a MoA of inhibiting heme polymerase, increasing free (toxic) heme?
Chloroquine
Mefloquine
Quinine & quinidine
Primaquine
What’s the MoA of atorvaquone?
Inhibits parasite mitochondrial electron transport
What’s the MoA of doxycycline?
A semi-synthetic tetracycline; inhibits protein synthesis in parasite organelles
What is the DOC to treat the SEVERE forms of malaria (when chloroquine-resistant)?
Quinine/quinidine
Which drug is considered a radical cure for exo-erythrocytic forms of P. vivax and ovale?
Primaquine
What are the side effects of chloroquine?
Pruritis (African-Americans)
What are the side effects of mefloquine?
*Neuropsychiatric toxicities: seizures, psychosis (less common w/prophylaxis); arrhythmias
What are the side effects of atovaquone?
GI side effects
What are the side effects of doxycycline?
Photosensitivity; esophagitis. Risk for vaginal candidasis.
What are the side effects of quinine/quinidine?
*Cinchonism (tinnutus, HA, nausea, dizziness, flushing, visual disturbances), hypoglycemia, blackwater fever,
Which anti-malarial can cause hemolysis in the G6PG deficient?
Primaquine
also contraindicated in granulocytopenia
What’s the MoA of artemisinin?
AKA Quinghausu
Binds iron in malaria pigment producing free radicals. *Rapidly acting schizonticide.
What are the side effects of artimisinin?
Potential neurotoxcity (ototoxicity) unresolved.
Which of the antimalarials are safest for children?
Which are “ok”?
Which are unsafe?
Safe: chloroquine, mefloquine
Okay: quinine/quinidine, primaquine
Unsafe: atovaquone, doxycycline
Which of the antimalarials are safest during pregnancy?
Which are “ok”?
Which are unsafe?
Safe: chloroquine
Okay: mefloquine (prophylaxis), quinine/quinidine (but causes contractions 3rd trimester)
Unsafe: mefloquine (tx), atovaquone (unless >5kg), doxycycline, primaquine
Atovaquone:
Besides being not okay in children <5kg, not okay during pregnancy unless benefit outweights risk (category C), atovaquone is also contraindicated in _______________.
Severe renal failure
Which anti-malarial is probably ok in children and pregnancy, but not approved in the US?
Artemisinin
When would you consider using doxycycline for malaria?
*Used for chemo-prophylaxis in areas of high mefloquine resistance (eg SE Asia).
*What is the DOC for malarial infection if resistance is not a concern?
Chloroquine
*What is the DOC for chemoprophylaxis in most regions (esp. if chloroquine-resistant), but is not recommended for tx of severe malaria?
Mefloquine
What’s the MoA for metronidazole?
Ferrodoxin-linked processes reduce nitro group to a product that is lethal vs. anaerobic organisms.
What are the side effects of metronidazole?
N/V, metallic taste, disulfuram-like rxn (w/etoh)
What are the side effects of iodoquinol?
N/V, neurotoxicity (all rare at recommended doses)
What are the side effects of nifurtimax?
GI, rash, CNS
What are the contraindications for metronidazole?
Interacts w/anti-coagulants, alcohol (used like antabuse), anticonvulsants
What are the side effects of albendazole?
- Short term: minimal
- Longer therapy: elevated aminotransferases, GI effects
2 day s/p therapy may see inflammation and increased ICP w/neurocystocercosis
What are the side effects of mebendazole?
Minimal GI to neutropenia and hepatic with long term therapy; hypersensitivity
What are the side effects of praziquantel?
(Mild) dizziness, HA, drowsiness, abdominal pain
What are the side effects of pyrantel pamoate?
Mild/transient
What are the side effects of ivermectin?
(Mild) hypersensitivity from worm death. Mazotti reaction (fever, HA’s, dizziness…)* – severe in onchocerciasis.
Which of the anti-helminthics are contraindicated in pregnancy and GI tract ulcers?
Albendazole Praziquantel Mebendazole Pyrantel pamoate Ivermectin
Besides being contraindicated in pregnancy and GI ulcers, when else is mebendazole contraindicated?
Children under 2
Besides being contraindicated in pregnancy and GI ulcers, when else is praziquantel contraindicated?
Ocular cysticercosis (inflammation)
Besides being contraindicated in pregnancy and GI ulcers, when else is pyrantel pamoate contraindicated?
Children under 2; liver disease
Besides being contraindicated in pregnancy and GI ulcers, when else is ivermectin contraindicated?
Co-existing CNS inflammation
Which anti-helminthic has decreased bioavailability w/corticosteroid therapy?
Praziquantel
Which anti-helminthic interacts w/carbamezapine and dilantin?
Mebendazole
What are the side effects for H2 blockers?
Hematopoietic and immune effects (B12 deficiency and Idiosyncratic myelosuppression); CNS (confusion, agitation); Hepatic effects (metabolized by cytochrome P450 and can cause drug interactions); Cardiac effects ([Brachycardia, hypotension due to increased vagal?], IV; cardiac toxicity, oral)
Cimetidine only: Inhibits CYP450; gynecomastia, impotence, elevated PRL (galactorrhea); mild increase in creatinine.”
How are H2 blockers eliminated?
What about cimetidine?
All mostly renal, except cimetidine is hepato-renal.
According to Hoppensteadt, what are the side effects of PPIs?
Few (< 3%), generally mild: diarrhea, headache, drowsiness, muscle pain and constipation
How are PPIs eliminated?
Hepatic
pro-drugs, activated in acidic compartment, then form disulfide bind w/p+ pump
Sucralfate: MoA?
Mucosal protective agent. Sulphated polysaccharide complexed with Al OH. Binds necrotic tissue to create barrier between the gastric contents and the mucosa.
Sucralfate: indications?
Effective at treating duodenal ulcers (not NSAID related) and the suppression of H. Pylori.
Sucralfate: side effects?
Constipation, dry mouth, nausea, diarrhea
How is sucralfate eliminated?
Renally
Can you give H2 inhibitors w/PPIs?
H2 antagonists should not be given simultaneously with PPIs because they reduce the efficacy of the PPIs.
What are antacids made of, and how do they work?
Neutralizes gastric and reduces delivery to the duodenum. Contain compounds such as Na HCO3, Al OH, Mg CO3 or Mg OH
Absorption of large amounts of antacids can lead to __________________.
What side effect is a/w antacids that contain Mg?
Milk-alkali syndrome (hypercalcemia, alkalosis, renal impairment)
Diarrhea
Compare and contrast the indications for H2 blockers vs. PPIs.
H2 blocks: GERD; gastric & duodenal ulcers (2nd line to PPI)
PPIs: GERD (erosive and non-erosive); duodenal and gastric ulcers, 1st-line (preferred for NSAID-induced ulcers); Zollinger-Ellison syndrome (gastrinoma); role in H. pylori tx.
