How do flea and tick tablets work? - briefly
Oral tablets deliver a systemic insecticide that is absorbed into the bloodstream, spreads throughout the animal’s tissues, and kills fleas and ticks when they feed. The active compound remains at therapeutic levels for several weeks, ensuring continuous protection without external application.
How do flea and tick tablets work? - in detail
Oral flea and tick medications are absorbed through the gastrointestinal tract and enter the bloodstream. After ingestion, the active compound circulates systemically, reaching the skin’s sebaceous glands and the surface lipid layer. When a parasite bites the host, it ingests blood containing the drug, which then interferes with essential neural or metabolic processes, leading to rapid paralysis and death.
The primary mechanisms differ among classes of compounds:
- Insect growth regulators (IGRs) such as methoprene or pyriproxyfen mimic juvenile hormone, preventing development of eggs and larvae. Adult fleas are unaffected, but the life cycle is interrupted, reducing population buildup.
- Neurotoxic agents like spinosad, a bacterial-derived compound, bind to nicotinic acetylcholine receptors, causing uncontrolled neuronal firing and fatal convulsions in both fleas and ticks.
- Isoxazoline class (e.g., fluralaner, afoxolaner) block ligand‑gated chloride channels (GABA‑ and glutamate‑gated), leading to hyperexcitation of the nervous system and rapid mortality.
- Antifeedant compounds such as nitenpyram act on the central nervous system of adult fleas, inducing quick knock‑down within minutes after a blood meal.
Pharmacokinetic profile determines duration of protection. Lipophilic agents persist in fatty tissues, providing several weeks of efficacy after a single dose. Hydrophilic molecules are eliminated more rapidly, requiring monthly administration. Dosage calculations are based on body weight to achieve therapeutic plasma concentrations while minimizing toxicity.
Safety considerations include:
- Metabolic pathways that convert the drug to inactive metabolites, reducing risk of accumulation.
- Selective toxicity that exploits differences between arthropod and mammalian nervous systems.
- Contraindications for breeding animals, very young or elderly pets, and individuals with known hypersensitivity.
Resistance management strategies involve rotating active ingredients with different modes of action and integrating environmental control measures such as regular vacuuming, washing bedding, and treating outdoor habitats. This multimodal approach slows the emergence of resistant flea and tick populations.