How does Stronghold work against fleas? - briefly
Stronghold contains spinosad, which binds to flea nervous‑system receptors, causing rapid paralysis and death. A single oral dose protects the animal for up to a month, eliminating current fleas and preventing new infestations.
How does Stronghold work against fleas? - in detail
Stronghold contains the active ingredient spinosad, a bacterial‑derived compound that disrupts the nervous system of fleas. After oral administration, the product is absorbed into the bloodstream and distributed throughout the animal’s tissues. Feeding fleas ingest spinosad when they blood‑feed, leading to rapid paralysis and death.
The mode of action involves binding to nicotinic acetylcholine receptors in the flea’s nervous system. This binding causes continuous stimulation of the receptors, resulting in uncontrolled nerve impulses. The overstimulation prevents normal muscle function, producing loss of coordination, inability to feed, and eventual mortality.
Key pharmacokinetic aspects:
- Peak plasma concentration occurs within 1–2 hours after dosing.
- Distribution reaches skin and fur in concentrations sufficient to affect adult fleas and developing stages.
- Elimination half‑life extends several weeks, maintaining effective levels for up to 30 days.
Efficacy against different life stages:
- Adult fleas die within 24 hours of feeding on treated hosts.
- Immature stages (eggs, larvae, pupae) are not directly targeted, but the reduction in adult populations curtails environmental contamination.
- Re‑infestation is prevented as long as plasma concentrations remain above the lethal threshold.
Resistance considerations:
- Spinosad’s unique binding site differs from that of pyrethroids and organophosphates, reducing cross‑resistance risk.
- Continuous exposure may select for mutations in the receptor, emphasizing the importance of integrated pest‑management strategies.
Safety profile:
- Selective toxicity to insects; mammals lack the specific receptor configuration, resulting in a high safety margin.
- Adverse effects are limited to occasional gastrointestinal upset or transient itching at the application site.
Overall, Stronghold provides a systemic, long‑lasting flea control solution by delivering spinosad into the host’s bloodstream, where it incapacitates feeding fleas through sustained neural hyper‑excitation.