Paromomycin
Paromomycin is an oral aminoglycoside antibiotic primarily utilized in veterinary medicine for its antiparasitic properties, specifically against **Cryptosporidium spp.** and **Leishmania spp.** Because it is structurally related to neomycin, it remains largely unabsorbed in the gastrointestinal tract when the mucosa is intact, allowing it to act locally on enteric pathogens. > **Clinical Pearl:** While effective for enteric protozoa, its use in cats is highly controversial due to reports of severe systemic toxicity (including acute kidney injury, ototoxicity, and blindness) even without obvious GI ulceration. Many clinicians prefer alternative therapies like azithromycin for felines.
Mechanism: Paromomycin binds to the **30S ribosomal subunit** of susceptible organisms โ causes misreading of mRNA โ inhibits protein synthesis, leading to cell death. In protozoa such as *Leishmania*, it is believed to target the mitochondria and ribosomes, disrupting cellular respiration and protein synthesis.
Dosing by species
- Treatment of cryptosporidiosis in Camelids (crias) ยท 50 mg/kg ยท PO ยท once per day (assumed) ยท 5-10 days ยท Dosing interval not specified in original source, assumed once per day by Plumb.
- Treatment of cryptosporidiosis ยท 125-165 mg/kg ยท PO ยท twice daily ยท 5 days ยท Consider using an alternate treatment first (e.g., azithromycin) or paromomycin at an initially reduced dosage level.
- Treatment of cryptosporidiosis ยท 150 mg/kg ยท PO ยท once a day ยท 5 days ยท Caution: nephrotoxicity.
- Treatment of cryptosporidiosis ยท 150 mg/kg ยท PO ยท q12-24hr ยท Until 1 week past clinical resolution of diarrhea ยท If the cat is responding to the first 7 days of therapy and toxicity has not been noted.
- Treatment of cryptosporidiosis ยท 125-165 mg/kg ยท PO ยท twice daily ยท 5 days
- Treatment of cryptosporidiosis ยท 150 mg/kg ยท PO ยท once a day ยท 5 days ยท Caution: nephrotoxicity.
- Treatment of cryptosporidiosis ยท 300-800 mg/kg ยท PO ยท q24-48h ยท 7-14 days or as needed
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Known hypersensitivity to paromomycin
- Ileus or intestinal obstruction
- Gastrointestinal ulceration
- Presence of blood in the stool (indicates mucosal breakdown and risk of systemic absorption)
Adverse effects
- Nausea
- Vomiting
- Diarrhea
- Inappetence
- Nonsusceptible bacterial or fungal overgrowth
- Nephrotoxicity (if systemically absorbed)
- Ototoxicity (if systemically absorbed)
- Pancreatitis (if systemically absorbed)
- Blindness (reported in cats)
Drug interactions
- Digoxin ยท Paromomycin may reduce digoxin absorption
- Methotrexate ยท Paromomycin may reduce methotrexate absorption
Monitoring
- Clinical efficacy (resolution of diarrhea, negative fecal tests)
- Gastrointestinal adverse effects
- Renal function (especially if used in cats or if GI ulceration is suspected)
Overdose
Because paromomycin is not absorbed orally, acute overdose adverse effects should be limited to **gastrointestinal distress** (nausea, vomiting, diarrhea) in patients with an intact GI system. **Chronic overdoses** or administration in patients with compromised GI mucosa may lead to severe systemic toxicity, including nephrotoxicity, ototoxicity, and pancreatitis.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.