Antiparasitic therapy Flashcards
Appropriate drugs
Effective against all stages of the species
Non-toxic, easily administered and cost efficient
Transdermal delivery
Lipophilic with large molecular weights
Slow dermal absorption
Long plasma and tissue t 1/2
Advantages of transdermal delivery
Easier application
Avoid first pass metabolism and GI degradation
Disadvantages of transdermal delivery
Licking → systemic exposure
Overdosing
Longer withdrawal times
Antiparasitic application
Spot on
Pour on/ spray on (1+ active ingredients)
Ear tags (insecticide, horn flies)
Baths
Insecticidal collar (ectoparasites)
What are the active ingredients in ear tags?
Organophosphate
Synthetic pyrethroid (fipronyl)
Baths
Plunge dip for cattle and sheep
Amitraz, organophosphate and synthetic pyrethroid
Good for attached ectoparasites
Requirements for antiparasitcs
Registered with the EPA and FDA focuses on the efficacy
What is the first sign of parasitic resistance?
Failure of treatment
Mechanisms of parasite resistance
- Multiple resistance (multi-drug)
- Reversible resistance (removal of selection pressure)
- Cross resistance (multiple receptors)
- Inherent resistance frequency
- Target site sensitivity (change in receptor structure)
- Metabolic (detoxify agent)
- Behavioral (move from treated surface)
- ↓ cuticular penetration
- Genetic polymorphisms
- Change in drug transport (P-glucoprotein)
- Changes in drug metabolism
Protozoal resistance
Leishmania and coccidia
Main mechanism: efflux pump
Types of acaricide/ insecticide resistance
Genotypic: underlying genes
Phenotypic: susceptibility when exposed to a standard dose
Resistance leading to control failure: failure to control an insect vectors disease trans
Last resort to resistance
Saturation
