How do flea and worm drops work for cats? - briefly
Topical flea products apply a systemic insecticide that penetrates the skin, circulates in the bloodstream, and kills adult fleas while disrupting their life cycle. Oral worming drops contain an anthelmintic absorbed through the gastrointestinal tract that interferes with the metabolism of intestinal parasites, leading to their elimination.
How do flea and worm drops work for cats? - in detail
Flea and worm spot‑on products are formulated as liquid solutions that disperse across the cat’s skin after a single application to the back of the neck. The active ingredients dissolve in the sebum and spread via the animal’s natural oil distribution system, reaching the entire body surface within hours.
The flea component typically contains an insect growth regulator (IGR) such as pyriproxyfen or a neurotoxin like imidacloprid. IGRs interrupt the development of eggs and larvae, preventing the emergence of adult fleas. Neurotoxins bind to nicotinic acetylcholine receptors in adult fleas, causing paralysis and death after contact with the cat’s fur.
The worm component usually includes a broad‑spectrum anthelmintic such as milbemycin oxime, praziquantel, or pyrantel pamoate. These agents are absorbed through the skin and gastrointestinal tract, entering the bloodstream. Once in circulation, they target specific parasites:
- Milbemycin oxime – blocks glutamate‑gated chloride channels in nematodes and heartworms, leading to paralysis and elimination.
- Praziquantel – increases calcium permeability in tapeworms, causing muscular contraction and disintegration.
- Pyrantel pamoate – acts as a nicotinic agonist on nematode neuromuscular junctions, inducing spastic paralysis.
After systemic absorption, the anthelmintic reaches the intestinal lumen, where adult worms reside, and exerts its lethal effect. The dead parasites are expelled in the feces, reducing reinfection risk.
Key pharmacokinetic steps include:
- Dermal absorption – lipid‑soluble molecules cross the stratum corneum.
- Distribution – compounds travel via the bloodstream to target tissues.
- Metabolic stability – chemical structure resists rapid degradation, ensuring therapeutic concentrations for several weeks.
- Excretion – metabolites are eliminated primarily through feces, minimizing environmental contamination.
The combined formulation provides simultaneous control of external ectoparasites and internal endoparasites, simplifying preventive care and reducing the need for multiple separate administrations. Regular monthly dosing maintains effective blood levels, interrupting parasite life cycles and protecting the cat’s health.