DO NOT MIX THOSE TWO DRUGS AT ALL -- what happens is the ketoconozole breaks the blood barrier wall thus allowing the ivermectin to go straight to the brain. It almost killed my friends yorkie. She was acting in a drunken stupor to begin with - you can google it --http://www.dermcare.com.au/pdf/2007_Spring_Newsletter.pdf
P-Glycoprotein issues: It doesn’t stop there:
P-glycoprotein deficiencies are not just genetic, they can also
be acquired. Ketoconazole is well recognised as a potent
inhibitor of P-glycoprotein. (8) In fact, ketoconazole will make
any breed of dog have a Collie-like potential for ivermectin
neurotoxicity. Ketoconazole is effectively the medical
equivalent of an MDR1 deletion, P-glycoprotein
deficiency. A recent study examining the effects of
ketoconazole on plasma levels of ivermectin found that coadministered
ketoconazole induced higher plasma
concentrations and longer clearance times of ivermectin. (8) It
has also been demonstrated that the incidence of adverse
effects of ketoconazole in dogs is higher in dogs on
concurrent cyclosporine, also a known P-glycoprotein
inhibitor. (9)
If we now reconsider the initial scenario with our
whippet cross patient, drugs that could be
considered for the treatment of its various ailments
include: ivermectin (for demodicosis) cyclosporine
for atopy (Cushingoid, therefore steroids are out)
and ketoconazole for Malassezia dermatitis. It is
not hard to see how easily an adverse reaction could
occur if we were not aware of all of the potential
risks of using multiple drug therapies.
The potential for life threatening interactions in
individuals with the MDR1 gene deletion or those
taking P-glycoprotein-reversal agents (inhibitors) is
enormous and something that needs to be carefully
considered when prescribing drug
Ivermectin
PLEASE DO NOT USE THOSE TWO DRUGS TOGETHER EVER - the dermatologist my friend went to did this and admitted she never should have mixed those drugs and she was sorry --sophie went into a drunken stupor, then seizures then coma, then got pneumonia
the new dermatologist is now using an antibiotic simplicef and 1/4 tablet of interceptor daily as it has a small dose of a drug like ivermectin. It is expensive but has been working on sophie so you may want to ask about that for demodex. Sophie is 6lbs