Drugs for Parasitic Infections (2013 Edition)
Total Page:16
File Type:pdf, Size:1020Kb
The Medical Letter publications are protected by US and international copyright laws. Forwarding, copying or any other distribution of this material is strictly prohibited. For further information call: 800-211-2769 Drugs for Parasitic Infections With increasing travel, immigration, use of immunosuppressive drugs and the spread of HIV, physicians anywhere may see infections caused by parasites. The table below lists first- choice and alternative drugs for most parasitic infections. The principal adverse effects of these druugs are listed on pages e24-27. The table that begins on page e28 summarizes the known pre- natal risks of antiparasitic drugs. The brand names and manufacturers of the drugs are listed on pages e30-31. ACANTHAMOEBA keratitis Drug of choice: Keratitis is typically associated with contact lens use.1 A topical biguanide, 0.02% chlorhexi- dine or polyhexamethylene biguanide (PHMB, 0.02%), either alone or combined with a diami- dine, propamidine isethionate (Brolene) or hexamidine (Desomodine), have been used suc- cessfully.2 They are administered hourly (or alternating every half hour) day and night for the first 48 hours and then continued on a reduced schedule for days to months.3 None of these drugs is commercially available or approved for use in the US, but they can be obtained from compounding pharmacies. Leiter’s Park Avenue Pharmacy, San Jose, CA (800-292-6773; www.leiterrx.com) is a compounding pharmacy that specializes in ophthalmic drugs. Expert Compounding Pharmacy, 6744 Balboa Blvd., Lake Balboa, CA 91406 (800-247-9767) and Medical Center Pharmacy, New Haven, CT (203-688-7064) are also compounding pharmacies. Other compounding pharmacies may be found through the National Association of Compounding Pharmacies (800-687-7850) or the Professional Compounding Centers of America (800-331-2498, www.pccarx.com). Propamidine is available over the counter in the UK and Australia. Hexamidine is available in France. Debridement is most useful during the stage of corneal epithelial infection; keratoplasty in medically unresponsive keratitis was suc- cessful in 31 eyes in 30 patients.4 Most cysts are resistant to neomycin; its use is no longer recommended. Azole antifungal drugs (ketoconazole, itraconazole) have been used as oral or topical adjuncts. Successful treatment with topical or oral voriconazole has been reported in a small number of patients who had failed PHMB, chlorhexidine and hexamidine.5,6 Use of corti- costeroids is controversial. Prolonged therapy (>6 months) may be necessary.2 1. FR Carvalho et al, Cornea 2009; 28:516. 2. JK Dart et al, Am J Ophthalmol 2009; 148:487. 3. GS Visvesvara, Curr Opin Infect Dis 2010; 23:590. 4. AS Kitzmann et al, Ophthalmology 2009; 116: 864. 5. BS Bang et al. Am J Ophthalmol 2010; 149:66. 6. EY Tu et al, Cornea 2010; 29:1066. Treatment Guidelines from The Medical Letter • Vol. 11 (Suppl) • 2013 e1 AMEBIASIS (Entamoeba histolytica) Drug Adult dosage Pediatric dosage Asymptomatic Drug of choice: Iodoquinol1 650 mg PO tid x 20d 30-40 mg/kg/d (max 2g) PO in 3 doses x 20d OR Paromomycin2 25-35 mg/kg/d PO in 3 doses x 7d 25-35 mg/kg/d PO in 3 doses x 7d OR Diloxanide furoate3* 500 mg PO tid x 10d 20 mg/kg/d PO in 3 doses x 10d Mild to moderate intestinal disease Drug of choice:4 Metronidazole 500-750 mg PO tid x 7-10d 35-50 mg/kg/d PO in 3 doses x 7-10d OR Tinidazole5 2 g once PO daily x 3d >3yrs: 50 mg/kg/d (max 2g) PO in 1 dose x 3d either followed by Iodoquinol1 650 mg PO tid x 20d 30-40 mg/kg/d (max 2g) PO in 3 doses x 20d OR Paromomycin2 25-35 mg/kg/d PO in 3 doses x 7d 25-35 mg/kg/d PO in 3 doses x 7d Severe intestinal and extraintestinal disease Drug of choice: Metronidazole 750 mg PO (or IV) tid x 7-10d 35-50 mg/kg/d PO (or IV) in 3 doses x 7-10d OR Tinidazole5 2 g once PO daily x 5d >3yrs: 50 mg/kg/d (max 2g) PO in 1 dose x 5d either followed by Iodoquinol1 650 mg PO tid x 20d 30-40 mg/kg/d (max 2g) PO in 3 doses x 20d OR Paromomycin2 25-35 mg/kg/d PO in 3 doses x 7d 25-35 mg/kg/d PO in 3 doses x 7d * Availability problems. See table of manufacturers on pages e30-31. 1. Iodoquinol should be taken after meals. 2. Paromomycin should be taken with a meal. 3. Not available commercially. It may be obtained through compounding pharmacies such as Expert Compounding Pharmacy, 6744 Balboa Blvd, Lake Balboa, CA 91406 (800-247-9767) or Medical Center Pharmacy, New Haven, CT (203-688-7064). Other compound- ing pharmacies may be found through the National Association of Compounding Pharmacies (800-687-7850) or the Professional Compounding Centers of America (800-331-2498, www.pccarx.com). 4. Nitazoxanide may be effective against a variety of protozoan and helminth infections (DA Bobak, Curr Infect Dis Rep 2006; 8:91; E Diaz et al, Am J Trop Med Hyg 2003; 68:384). It is effective against mild to moderate amebiasis, 500 mg PO bid x 3d (JF Rossignol et al, Trans R Soc Trop Med Hyg 2007; 101:1025; AE Escobedo et al, Arch Dis Child 2009; 94:478), but perhaps less so than metronida- zole (S Becker et al, Am J Trop Hyg 2011; 84:581). Nitazoxanide is FDA-approved only for treatment of diarrhea caused by Giardia or Cryptosporidium (Med Lett Drugs Ther 2003; 45:29). It is available in 500-mg tablets and an oral suspension and should be taken with food. 5. A nitroimidazole similar to metronidazole, tinidazole appears to be as effective as metronidazole and better tolerated (Med Lett Drugs Ther 2004; 46:70). It should be taken with food to minimize GI adverse effects. For children and patients unable to take tablets, a phar- macist can crush the tablets and mix them with cherry syrup (Humco, and others). The syrup suspension is good for 7 days at room temperature and must be shaken before use (HB Fung and TL Doan, Clin Ther 2005; 27:1859). Ornidazole, a similar drug, is also used outside the US. Treatment Guidelines from The Medical Letter • Vol. 11 (Suppl) • 2013 e2 AMEBIC MENINGOENCEPHALITIS, primary and granulomatous1 Drug Adult dosage Pediatric dosage Primary Amebic Meningoencephalitis (PAM) – Naegleria fowleri 2,3 Drug of choice: Amphotericin B 0.25 mg/kg IV over 4-6 h. 0.25 mg/kg IV over 4-6 h. (conventional If tolerated, 0.5 mg/kg IV the If tolerated, 0.5 mg/kg IV the formulation)4 following day, increasing to following day, increasing to 1.5 1.5 mg/kg IV once/d as tolerated mg/kg IV once/d as tolerated (max 1.5 mg/kg/day) (max 1.5 mg/kg/day) or 1 mg/kg IV once/d plus 0.5 mg/d 1 mg/kg IV once/d plus 0.5 mg/d intraventricularly (can start with intraventricularly (can start with 0.025-0.050 mg/d and increase 0.025-0.050 mg/d and increase to 0.5 mg/d)5 (max 1.5 mg/kg to 0.5 mg/d)5 (max 1.5 mg/kg once/d total dosage by both IV once/d total dosage by both IV and intraventricular routes) and intraventricular routes) Rifampin 10 mg/kg IV once/d (max 600 10 mg/kg IV once/d (max 600 mg/d) mg/d) Fluconazole 12 mg/kg IV once/d 12 mg/kg IV once/d Azithromycin 500 mg IV once/d 20 mg/kg IV once/d (max 500 mg/d) Granulomatous Amebic Encephalitis (GAE) – Acanthamoeba spp.6-8 Pentamidine9 4 mg/kg IV once/d 4 mg/kg IV once/d Sulfadiazine 1.5 g q6h PO 200 mg/kg/d PO in 4-6 doses (max 6 g/d) Flucytosine 37.5 mg/kg PO q6h (max 150 mg/ 37.5 mg/kg PO q6h (max 150 mg/ kg/d) kg/d) Fluconazole 12 mg/kg IV once/d 12 mg/kg IV once/d Miltefosine10 <45 kg: 100 mg/d PO in 2 doses 2.5 mg/kg/d PO in 2 doses >45 kg: 150 mg/d PO in 3 doses (max 100 mg/d) Granulomatous Amebic Encephalitis (GAE) – Balamuthia mandrillaris11-16 Azithromycin 500 mg IV once/d 20 mg/kg IV once/d (max 500 mg/d) Clarithromycin 14 mg/kg/d PO in 2 doses (max 14 mg/kg/d PO in 2 doses (max 2 g/d) 2 g/d) Pentamidine9 4 mg/kg IV once/d 4 mg/kg IV once/d Sulfadiazine 1.5 g PO q6h 200 mg/kg/d PO in 4-6 doses (max 6 g/d) Flucytosine 37.5 mg/kg PO q6h (max 150 37.5 mg/kg PO q6h (max 150 mg/kg/d) mg/kg/d) Fluconazole 12 mg/kg IV once/d 12 mg/kg IV once/d Miltefosine10 <45 kg: 100 mg/d PO in 2 doses 2.5 mg/kg/d PO in 2 doses (max >45 kg: 150 mg/d PO in 3 doses 100 mg/d) 1. Meningoencephalitis caused by the free-living amebae Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris has a mortality rate of >90%; effective treatment has not been established. Treatment recommendations are based on case reports of sur- vivors, animal studies, and in vitro drug testing.