Anti-protozoal drugs Flashcards
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
What is the first-line drug for acute invasive amoebic dysentery?
Metronidazole
- 800mg 3 times a day for 5 days (10 days if extra-intestinal infection) (adult)
Followed by 10-day course of diloxanide furoate
Second line: tinidazole
- 2g once daily for 2-3 days (adult)
Metronidazole: https://bnf.nice.org.uk/drug/metronidazole.html
Tinidazole:
https://bnf.nice.org.uk/drug/tinidazole.html
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
For the treatment of acute invasive dysentery, following metronidazole (or tinidazole), what drug do you give for 10 days to destroy any amoebae in the GI tract?
Diloxanide furoate
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
What is the drug of choice for asymptomatic patients with Entamoeba histolytica cysts in the faeces?
Diloxanide furoate
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
What are the two drug options for amoebic abscesses of the liver?
Metronidazole
- 800mg 3 times a day for 5 days (10 days if extra-intestinal infection) (adult)
Tinidazole
- 1.5-2 g once daily for 3-6 days (adult)
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
What is the first-line drug for the treatment of Trichomonas vaginalis?
Metronidazole
- 200 mg 3 times a day for 7 days (or 400-500 mg twice a day for 5-7 days or 2 g for 1 dose) (adult)
Second line: tinidazole
- 2g for 1 single dose
Metronidazole:
https://bnf.nice.org.uk/drug/metronidazole.html
Tinidazole:
https://bnf.nice.org.uk/drug/tinidazole.html
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
What is the first-line drug for the treatment of Giardia lamblia infections?
Metronidazole
- 2 mg once daily for 3 days (alternative 400 mg 3 times a day for 5 days or 500 mg twice daily for 7-10 days)
Second line (2 options): Tinidazole - 2 g for 1 single dose OR Mepacrine hydrochloride - 100 mg every 8 hours for 5-7 days
Metronidazole:
https://bnf.nice.org.uk/drug/metronidazole.html
Tinidazole:
https://bnf.nice.org.uk/drug/tinidazole.html
Mepacrine hydrochloride:
https://bnf.nice.org.uk/drug/mepacrine-hydrochloride.html
What is the one indication for use of the drug mepacrine hydrochloride?
Giardiasis
- by mouth 100 mg every 8 hours for 5-7 days
(mepacrine hydrochloride is a second-line drug for giardiasis)
First-line for Giardiasis: Metronidazole
- 2 mg once daily for 3 days (alternative 400 mg 3 times a day for 5 days or 500 mg twice daily for 7-10 days)
Mepacine hydrochloride:
https://bnf.nice.org.uk/drug/mepacrine-hydrochloride.html
What is the first-line drug for the treatment of visceral leishmaniasis (kala-azar)?
Sodium stibogluconate (antimony compound)
Second line: amphotericin B (in combination or after sodium stibogluconate)
What is the management of cutaneous leishmaniasis if the skin lesions are NOT extensive or unsightly?
Nothing - lesions will heal spontaneously
If skin lesions are extensive or unsightly: sodium stibogluconate +/- amphotericin B (same as visceral leishmaniasis)
Amoebic abscesses of the liver require aspiration if… (3)
- Suspected that they may rupture
- No improvement after 72 hours of metronidazole treatment
- Abscess > 100 ml of pus
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
If toxoplasmosis is acquired during pregnancy, what unlicensed drug may reduce the risk of transmission of maternal infection to the fetus?
Spiramycin
https://bnf.nice.org.uk/treatment-summary/antiprotozoal-drugs.html
What is the first-line treatment of toxoplasmosis in HIV/immunosuppressed patients?
Pyrimethamine + sulfadiazine for several weeks (> 6 weeks)
Alternatives:
Pyrimethamine + clindamycin
OR
Clarithromycin + azithromycin
If a patient is taking pyrimethamine for the treatment of toxoplasmosis, what investigation do they need to do weekly to watch out for adverse effects?
Weekly blood counts
Pyrimethamine is a folate antagonist, common side effects include leucopenia and thrombocytopenia
Patient should also take folinic acid supplements
https://bnf.nice.org.uk/drug/pyrimethamine.html
Metronidazole is an antimicrobial drug with high activity against … (2)
- Anaerobic bacteria
- Protozoa
https://bnf.nice.org.uk/drug/metronidazole.html
From top 100: metronidazole enters bacterial cells by passive diffusion. In anaerobic bacteria, the reduction of metronidazole generates a nitroso free radical. This binds to DNA, reducing synthesis and causing widespread damage, DNA degradation and cell death (bactericidal)
Which protozoal infections is metronidazole indicated for treatment? (3)
- Amoebiasis (invasive intestinal and extra-intestinal, including liver abscess)
- Adult dose: 800 mg 3 times a day for 5 days in intestinal infection (for 5-10 days in extra-intestinal infection) - Urogenital trichomoniasis
- Adult dose: 200 mg 3 times a day for 7 days, alternatively 400-500 mg twice daily for 5-7 days, or 2 g for 1 dose - Giardiasis
- Adult dose: 2 g daily for 3 days, alternatively 400 mg 3 times a day for 5 days, alternatively 500 mg twice daily for 7-10 days
https://bnf.nice.org.uk/drug/metronidazole.html
What is the route of administration of metronidazole for the protozoal infections (amoebiasis, trichomoniasis and giardiasis)?
Oral
- Amoebiasis (invasive intestinal and extra-intestinal, including liver abscess)
- Adult dose: 800 mg 3 times a day for 5 days in intestinal infection (for 5-10 days in extra-intestinal infection) - Urogenital trichomoniasis
- Adult dose: 200 mg 3 times a day for 7 days, alternatively 400-500 mg twice daily for 5-7 days, or 2 g for 1 dose - Giardiasis
- Adult dose: 2 g daily for 3 days, alternatively 400 mg 3 times a day for 5 days, alternatively 500 mg twice daily for 7-10 days
What is the effect of drinking alcohol while taking metronidazole?
Disulfiram-like reaction
Symptoms: flushing, headache, nausea and vomiting
Avoid alcohol for at least 48 hours after stopping treatment
What effect does metronidazole have on CYP enzymes?
Inhibitory effect
Reduces the metabolism of warfarin (increasing the risk of bleeding) - monitor INR and adjust dose
https://bnf.nice.org.uk/interaction/metronidazole-2.html#bnf_i1630548642590
What happens when you combine metronidazole with lithium?
Metronidazole increases the concentration of lithium
What are the neurological adverse effects of metronidazole at high doses or for a prolonged course?
- Peripheral neuropathy
- Optic neuropathy
- Seizures
- Encephalopathy
Tinidazole is an antimicrobial drug with high activity against … (2)
- Anaerobic bacteria
- Protozoa
Same as metronidazole.
Tinidazole has a longer duration of action than metronidazole
https://bnf.nice.org.uk/drug/tinidazole.html
What are the indications for tinidazole? (9)
- Anaerobic infections
- Bacterial vaginosis
- Acute ulcerative gingivitis
- Abdominal surgery prophylaxis
- Intestinal amoebiasis
- Amoebic involvement of liver
- Urogenital trichomoniasis
- Giardiasis
- Helicobacter pylori eradication
https://bnf.nice.org.uk/drug/tinidazole.html
What are the indications of liposomal amphotericin B (AmBisome)? (4)
- Severe systemic or deep mycoses where toxicity precludes the use of conventional amphotericin B
2 Suspected or proven infection in febrile neutropenic patients unresponsive to broad-spectrum antibacterial
- Aspergillosis
- Visceral leishmaniasis (unresponsive to antimonial alone)
https: //bnf.nice.org.uk/drug/amphotericin-b.html
What is the route of admission of liposomal amphotericin B (AmBisome)?
IV infusion
Why should you avoid rapid infusion of amphotericin B?
Risk of arrhythmias
https://bnf.nice.org.uk/drug/amphotericin-b.html
What are the indications for pentamidine isetionate? (5)
- Pneumocystis jirovecii pneumonia (IV infusion)
- 4 mg/kg once daily for at least 14 days - Prophylaxis of Pneumocystis jirovecii pneumonia (inhalation of nebulised solution)
- 300 mg every 4 weeks, alternatively 150 mg every 2 weeks - Visceral leishmaniasis (deep IM injection)
- 3-4 mg/kg once daily on alternate days, maximum total of 10 injections, course may be repeated - Cutaneous leishmaniasis (deep IM injection)
- 3-4 mg/kg 1-2 times a week - Trypanosomiasis (deep IM injection or IV infusion)
- 4 mg/kg once daily or on alternate days for 7-10 injections
https://bnf.nice.org.uk/drug/pentamidine-isetionate.html
What supplement should a patient take if they are being treated for toxoplasmosis with pyrimethamine?
Folinic acid supplements
Pyrimethamine is a folate antagonist
A patient with antimony-resistant visceral leishmaniasis is being treated with pentamidine isetionate. What is the route of administration?
Deep IM injection
3-4 mg/kg once daily on alternate days, maximum of 10 injections, course may be repeated if necessary