How does a flea tablet work? - briefly
The tablet delivers a systemic insecticide that enters the animal’s blood and is transferred to feeding fleas, causing rapid death. The compound disperses through the skin and fur, maintaining protection for several weeks.
How does a flea tablet work? - in detail
Oral flea treatments deliver an active compound that is absorbed through the gastrointestinal tract, enters the bloodstream, and reaches the skin’s surface where fleas feed. After ingestion, the drug is rapidly taken up by the intestinal wall; plasma concentrations peak within a few hours. The systemic circulation distributes the molecule throughout the body, including the sebaceous glands that secrete oils onto the coat. Fleas ingest the drug during a blood meal, triggering the intended lethal effect.
The primary mechanisms differ by ingredient:
- Neurotoxic agents (e.g., nitenpyram, spinosad). These compounds bind to specific receptors in the flea nervous system—nicotinic acetylcholine receptors for nitenpyram and nicotinic/acetylcholine sites for spinosad. Binding forces continuous nerve firing, causing rapid paralysis and death within minutes.
- Insect growth regulators (e.g., lufenuron). Lufenuron interferes with chitin synthesis, preventing the formation of a functional exoskeleton in developing larvae. Adult fleas remain unaffected, but eggs and larvae fail to mature, breaking the life cycle over weeks.
- Metabolic disruptors (e.g., afoxolaner, fluralaner). These molecules block GABA‑gated chloride channels, leading to uncontrolled neuronal excitation. Fleas die after several days of feeding, providing extended protection.
Pharmacokinetics ensure efficacy while limiting toxicity. The drug’s half‑life ranges from hours (neurotoxins) to weeks (long‑acting isoxazolines), allowing a single dose to protect the animal for 30 days or more. Metabolism occurs primarily in the liver; inactive metabolites are excreted via urine and feces. Dosage calculations are based on body weight to maintain plasma levels above the lethal concentration for fleas but below the threshold that affects mammalian physiology.
Safety considerations include:
- Species‑specific approval; many tablets are formulated for dogs, some for cats, with different active ingredients.
- Contra‑indications for animals with known hypersensitivity or concurrent use of certain other medications.
- Monitoring for adverse reactions such as vomiting, diarrhea, or neurological signs, which are rare when dosing guidelines are followed.
In practice, the tablet is administered orally, either as a chewable tablet or a flavored pill. The animal’s systemic circulation becomes a continuous source of flea‑targeted toxin, ensuring that any flea that bites receives a lethal dose, thereby eliminating existing infestations and preventing new ones for the duration of the product’s activity.