Benzodiazepines:  Ivermectin may potentiate the activity of benzodiazepines.  Concurrent therapy with ivermectin & benzodiazepines is not recommended.

Inducers or Inhibitors of the p-Glycoprotein Transport System:  Ivermectin appears to be a substrate of the p-glycoprotein transport system; thus, interactions with inhibitors (e.g., amiodarone, carvedilol, clarithromycin, cyclosporine, erythromycin, itraconazole, ketoconazole, quinidine, ritonavir, tamoxifen, & verapamil) or inducers (e.g., amprenavir, clotrimazole, phenothiazines, rifampin, ritonavir, & St. John’s wort) of the p-glycoprotein transporter are theoretically possible.

Alcohol:  Concurrent administration of single doses of ivermectin (150 mcg/kg) & alcohol 4.5% v/v (400 mg/kg average dose) resulted in substantial increases in plasma ivermectin concentrations in healthy individuals, indicating a potential pharmacokinetic interaction. (IMHO, increasing the plasma concentration is a good thing.  You get more drug in the blood to blast the bstrds, more bang for your meds $buck$, & a nice toddy for the body ~~ lol.  That's why I take the vet med Agrimectin cattle pour-on suspension since it's alcohol-based & the tablets, paste, & other types of suspensions aren't.) 

Anticoagulants:  In one patient receiving acenocoumarol (not commercially available in the US), excessive hypocoagulability was reported after occupational contact with insecticide formulations of ivermectin (Epimek, not commercially available in the US) & metidation (Ultracid, not commercially available in the US).  The manufacturer states that no additional case reports of an interaction between ivermectin & oral anticoagulants have been received to date.

(Extract from Medscape Ivermectin Drug Monograph: http://www.medscape.com/druginfo/monograph?cid=med&drugid=17846&drugn...)

Hope this info helps you in your parasite battles!