How do flea tablets work? - briefly
Flea tablets deliver a systemic insecticide that enters the animal’s bloodstream after oral ingestion; feeding fleas ingest the toxin and are killed. The active agents, such as nitenpyram or spinosad, act rapidly to eradicate current fleas and deter new ones.
How do flea tablets work? - in detail
Flea tablets are administered orally, enter the bloodstream, and become available in the tissues that fleas contact while feeding. After ingestion, the active compounds are absorbed through the gastrointestinal lining, reach peak plasma concentrations within a few hours, and are distributed to skin, hair follicles, and sebaceous secretions. When a flea ingests blood containing the drug, the insect’s physiological processes are disrupted, leading to death or loss of reproductive capacity.
Active ingredients fall into three principal categories:
- Neurotoxic agents (e.g., nitenpyram, spinosad). These bind to insect-specific nicotinic acetylcholine receptors or GABA-gated chloride channels, causing uncontrolled nerve firing, paralysis, and rapid mortality, typically within 30 minutes to 2 hours after a flea feeds.
- Chitin synthesis inhibitors (e.g., lufenuron). By blocking the formation of chitin, these compounds prevent the development of eggs and larvae, reducing environmental flea populations. Adult fleas are not killed directly; instead, their progeny fail to mature.
- Insect growth regulators (e.g., pyriproxyfen). These mimic juvenile hormone, interfering with metamorphosis and leading to malformed or non‑viable offspring.
Pharmacokinetic characteristics determine efficacy. Oral doses are formulated to achieve concentrations that exceed the lethal dose for fleas while remaining well below toxic thresholds for mammals. The drug’s half‑life ranges from 12 hours for fast‑acting neurotoxins to several days for IGRs, supporting single‑dose or monthly regimens. Metabolism occurs primarily in the liver, with excretion via urine and feces; minimal residues accumulate in the animal’s tissues.
Safety considerations include a wide therapeutic index, limited systemic toxicity, and low risk of dermal irritation because the active ingredient is not applied topically. Nevertheless, contraindications exist for pregnant or lactating animals and for species with known hypersensitivity.
Resistance management relies on rotating classes of oral flea control agents, avoiding repeated use of the same neurotoxic compound. Monitoring for reduced efficacy and adjusting treatment protocols help sustain long‑term control of flea infestations.