MDR1 Veterinary Fact Sheet

 Download and print the MDR1 Problem Drug Info Sheet

The multi-drug resistance gene (MDR1) encodes P-glycoprotein, a protein that functions as a drug-transport pump across cell membranes. A lack of P-glycoprotein means certain drugs cannot be absorbed, distributed or metabolized normally (particularly affecting the brain). Dogs with the MDR1 genetic mutation have a P-glycoprotein deficiency and are extremely susceptible to toxicosis from many common drugs.

Affected Breeds
The MDR1 mutation has been documented in many herding breeds and some sight hounds. The breeds affected by the MDR1 mutation (frequency %) is shown below.
 

Breed

Approximate Frequency

Australian Shepherd

50%

Australian Shepherd, Mini

50%

Border Collie

< 5%

Collie

70%

English Shepherd

15%

German Shepherd

10%

Herding Breed Cross

10%

Long-haired Whippet

65%

McNab

30%

Mixed Breed

5%

Old English Sheepdog

5%

Shetland Sheepdog

15%

Silken Windhound

30%


MDR1 Mutation Test
The Veterinary Clinical Pharmacology Laboratory (VCPL) at Washington State University has developed a commercially available test for the MDR1 mutation. Any dog of any breed can be tested via DNA collected from a cheek swab. Results are reported as homozygous for the normal MDR1 allele (normal/normal), heterozygous (mutant/normal), or homozygous for the mutant MDR1 allele (mutant/mutant). Dogs carrying the mutant gene or dogs from affected breeds that have not been tested for the mutation should not be given any of the MDR1 problem drugs.  Order a testing kit by contacting the Veterinary Clinical Pharmacology Laboratory at Washington State University: http://vcpl.vetmed.wsu.edu/ or by phone at 509-335-3745.

Problem Drugs
The most serious adverse drug reactions involve several antiparasitic agents (ivermectin, milbemycin, and related drugs), the over-the-counter antidiarrheal agent loperamide (Imodium), and several anticancer drugs (vincristine, doxorubicin, and others). These drug sensitivities result from a mutation in the multidrug resistance gene (MDR1 gene).

For the most up-to-date version of the MDR1 Problem Drug List, visit the WSU Problem Drug List website. vcpl.vetmed.wsu.edu/problem-drugs.

Dogs who test as having a mutated MDR1 gene OR dogs from affected breeds who have not been tested for the mutation should avoid these drugs.

Drug names in bold are the generic drugs identified as problems by the MDR1 researchers. Below each generic drug is a list of some of the synonyms, brand, and trade names for the generic drug provided by BusterAlert.org. More drugs are likely to be added as MDR1 research progresses.
 

Drugs Affected by the MDR1 Gene Mutation

Acepromazine

Ivermectin

Loperamide

Paclitaxel

Ace

Abamectin

Acanol

Abraxane

Acepro

Acarexx

Acqta

Taxol

Aceproject

Advantage DUO

Anti-Diarrheal Formula

Onxol

Acevet

Avermectin

Cryoperacid

Ribampin

ACP

Bimectin

Deroser

Ricilin

Atravet

BMD/Ivomec

Diahalt

Rifaldin

PromAce

Ecomectin

Diamode

Rifamp

Butorphanol

Equell

Diarr-Eze

Selamectin

Dolorex

Equimax

Diarrhea Relief

Revolution Topical

Stadol

Equimectrin

Hurplex

Stronghold

Torbugesic

Eqvalan

Imodium

Vinblastine

Torbutrol

Heartgard

Imogen

Lemblastine

Torphajet

Ivercare

Imotil

Solbalstin

Doxorubicin

Ivercide

Imperim

Velban

Adriamycin

Iverhart

Kao-Paverin Caps

Velbe

Adriblastina

Iver-On

Lop

Vincrex

Caelyx

Iversol

Loperacap

Vintec

Doxil

Ivexterm

Nodiamex

Vincristine

Doxolem

Ivomec

Permidal

Citomid

Doxotec

Mectizan

Pramidal

Leurocristine

Hydroxydaunomycin

Megamectin

Raxamida

Oncovin

Hydroxydoxorubicin

Noromectin

Rediarin

Vinblax

Hydroxyldaunorubicin

Panomec

Top-Dal

Vincasar

Myocet

Phoenectin

Valfam

Vincrex

Rubex

Primectin

Milbemycin

Vintec

Erythromycin

Privermectin

Inteceptor

Vinorelbine

Abboticne

SparMectin

Sentinel

Navelbine

Aknin

Stromectol

Moxidectin

 

Aipimycin

Tri-Heart

Guardian Moxidectin

 

Erythrocin

Unimectrin

Proheart

 

Iliocin

Virbamec

 

 

 

Zimecterin

 

 

This list is not inclusive. For more information and updates on the Problem Drug List, see vcpl.vetmed.wsu.edu/problem-drugs.
To find more generic and brand names of these drugs, see http://www.igenericdrugs.com/

 

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