Paromomycin sulfate is used as a luminal amebicide in the treatment of amebiasis caused by Entamoeba histolytica. A luminal amebicide generally is sufficient for the treatment of asymptomatic cyst passers who have only intraluminal infections; however, treatment of symptomatic intestinal amebiasis or extraintestinal disease involves the use of several drugs to ensure eradication of tissue-invading trophozoites as well as cysts in the intestinal lumen.
Paromomycin is used alone for the treatment of asymptomatic intestinal amebiasis and is considered a drug of choice for the treatment of asymptomatic cyst passers, especially in children and pregnant women. Other luminal amebicides that can be used for the treatment of asymptomatic cyst passers include oral iodoquinol or diloxanide furoate (not commercially available in the US).
Some strains of Entamoeba are nonpathogenic (e.g., E. dispar, E. hartmanni) and asymptomatic intraluminal infections with these organisms generally do not require treatment. A high percentage of Entamoeba recovered from the intestinal tracts of homosexual males appear to be nonpathogenic. However, some of these nonpathogenic strains are difficult to differentiate from pathogenic E. histolytica without specialized testing. Because of the risk of invasive amebiasis if asymptomatic E. histolytica infections are not treated, many clinicians suggest that asymptomatic cyst passers in areas nonendemic for E. histolytica receive treatment with a luminal amebicide. Treatment of asymptomatic cyst passers in endemic areas (e.g., Mexico, India, Southern and Western Africa, Far East, portions of Central and South America) is more controversial.
Although paromomycin may be effective for the treatment of mild intestinal amebiasis, the drug acts principally as a luminal amebicide and should not be used alone for the treatment of severe intestinal and extraintestinal amebiasis. The regimen of choice for symptomatic intestinal amebiasis or extraintestinal disease (including liver abscess) is treatment with a nitroimidazole derivative (oral metronidazole or oral tinidazole) followed by treatment with a luminal amebicide (oral iodoquinol or oral paromomycin). When used as follow-up after a tissue amebicide (e.g., metronidazole), paromomycin eradicates encysted E. histolytica in the intestinal lumen. Paromomycin may be preferred, rather than iodoquinol or diloxanide furoate, in children or pregnant women.
Paromomycin has been used with some success for the treatment of balantidiasis caused by Balantidium coli. However, tetracycline is considered the drug of choice and metronidazole and iodoquinol are alternatives for treatment of balantidiasis.
Cestode (Tapeworm) Infections
Paromomycin has been used effectively for the treatment of cestodiasis (tapeworm infection) caused by certain cestodes pathogenic to humans including Diphyllobothrium latum (fish tapeworm), Dipylidium caninum (dog and cat tapeworm), Hymenolepis nana (dwarf tapeworm), Taenia saginata (beef tapeworm), and T. solium (pork tapeworm). However, other agents (e.g., praziquantel, niclosamide [not commercially available in the US], nitazoxanide) currently are recommended for the treatment of these tapeworm infections.
Paromomycin reportedly has been beneficial in the treatment of cryptosporidiosis caused by Cryptosporidium parvum in some patients with human immunodeficiency virus (HIV) infection. A regimen of paromomycin and azithromycin was used with some success (i.e., reduced oocyst excretion, improvement in diarrhea) in a limited number of patients with AIDS and cryptosporidiosis. However, results of a prospective, double-blind, placebo-controlled study in symptomatic HIV-infected individuals found that paromomycin (500 mg 4 times daily for 21 days) was no more effective than placebo for the treatment of cryptosporidiosis.
The duration and severity of clinical symptoms of cryptosporidiosis vary depending on the immune status of the patient. Immunocompetent individuals usually have disease that is asymptomatic or self-limited (i.e., acute, watery diarrhea that persists for up to 2 weeks and may be accompanied by nausea, vomiting, abdominal pain, fever); however, immunocompromised individuals can have disease that manifests either as asymptomatic shedding of cryptosporidial oocysts or as transient infection with diarrhea lasting less than 2 months, chronic diarrhea lasting 2 months or longer with persistence of parasites in stool or biopsy specimens, or fulminant cholera-like illness. The severity of symptoms of cryptosporidiosis in HIV-infected individuals appears to depend on the CD4 T-cell count, and fulminant infections usually have occurred in those with CD4 T-cell counts less than 50/ mm. No anti-infective agent has been found to reliably eradicate Cryptosporidium, although several drugs (e.g., paromomycin, azithromycin, nitazoxanide) appear to suppress the infection.
The US Centers for Disease Control and Prevention (CDC), National Institutes of Health (NIH), and Infectious Diseases Society of America (IDSA), and other clinicians state that the most appropriate treatment for cryptosporidiosis in HIV-infected individuals is the use of potent antiretroviral agents and symptomatic treatment of diarrhea. A highly potent antiretroviral regimen can result in immune restoration (CD4 T-cell counts exceeding 100/ mm) which usually results in resolution of the infection. Symptomatic treatment of diarrhea in HIV-infected or immunocompetent individuals with cryptosporidiosis should include oral or IV fluids and electrolyte replacement to correct dehydration and nutritional supplementation when necessary; severe diarrhea may require intensive support. Adjunctive use of antimotility agents may be indicated, but these agents are not consistently effective and should be used with caution in young children.
Dientamoeba fragilis Infections
Paromomycin is considered a drug of choice for the treatment of infections caused by Dientamoeba fragilis. Iodoquinol, paromomycin, tetracycline, or metronidazole are the drugs of choice for the treatment of D. fragilis infections.
Paromomycin sulfate is considered an alternative for the treatment of giardiasis caused by Giardia duodenalis (also known as G. lamblia or G. intestinalis).
Drugs of choice for the treatment of giardiasis are metronidazole, tinidazole, or nitazoxanide; alternative agents include paromomycin (especially in pregnant women), furazolidone (no longer commercially available in the US), or quinacrine (not commercially available in the US). Although paromomycin may be less effective than the other agents, the drug is poorly absorbed from the GI tract and may be useful for the treatment of giardiasis in pregnant women.
Paromomycin has been used in the management of hepatic coma as an adjunct to protein restriction and supportive therapy to inhibit nitrogen-forming bacteria of the GI tract. However, nonabsorbable disaccharides (lactulose) or certain other anti-infectives (neomycin or metronidazole) usually are recommended for such adjunctive therapy.
Paromomycin sulfate has been used topically (in conjunction with topical methylbenzethonium chloride) for the treatment of cutaneous leishmaniasis. This topical regimen administered twice-daily for 10-20 days has been effective in some patients for the treatment of cutaneous leishmaniasis caused by Leishmania major; however, topical paromomycin should be used only in geographic regions where cutaneous leishmaniasis species have low potential for mucosal spread.
The treatment of choice for cutaneous leishmaniasis usually is pentavalent antimony compounds (IM or IV sodium stibogluconate or meglumine antimonate [drugs not commercially available in the US]); topical paromomycin or IM or IV pentamidine are alternatives.
Topical treatment cannot cure lymph node infection or protect against mucosal disease if metastasis has already started. Prolonged (e.g., twice daily for about 3 months) topical therapy has eliminated the protozoa from cutaneous lesions in patients with recurrent disease (leishmaniasis recidivans), and elimination of protozoa has occurred within 10-30 days of twice-daily therapy in patients with acute cutaneous leishmaniasis. If effective, clinical healing of lesions usually is complete within several weeks to a month after completion of topical paromomycin therapy.
Visceral Leishmaniasis (Kala-azar)
Paromomycin sulfate has been used IM for the treatment of visceral leishmaniasis (kala-azar).
The treatment of choice for visceral leishmaniasis usually is pentavalent antimony compounds (e.g., IM or IV sodium stibogluconate or meglumine antimonate [drugs not commercially available in the US]) or IV amphotericin B (conventional or liposomal); IM or IV pentamidine or IM paromomycin are alternatives.
In an open-label, prospective, randomized study in patients 5-55 years of age with visceral leishmaniasis, IM paromomycin (11 mg/kg daily for 21 days) was noninferior to IV amphotericin B (1 mg/kg of conventional amphotericin B every other day for 30 days). The final cure rate 6 months after the end of treatment was 95% in patients who received paromomycin and 99% in those who received amphotericin B.
Paromomycin has been used for the treatment of acute bacillary dysentery, carrier states of Shigella, and gastroenteritis caused by Escherichia coli, but other agents are preferred.