MOZZIGUARD MOSQUITO REPELLENT

Indications

• Insect repellent for mosquitoes
• Insect repellent for ticks
• Protection against biting insects

Dosage

Children: Refer to BNF for Children for specific dosage guidelines based on age and weight, as recommendations may vary.

Adults: Apply to exposed skin as needed, avoiding contact with eyes and mouth. Reapply after swimming or sweating, and follow product-specific guidance for concentration and frequency of use.

Mechanism of action

The exact mechanism of action of DEET is not fully elucidated, but it is believed to block the olfactory receptors in insects that are sensitive to 1-octen-3-ol, a compound found in human sweat. This blockade disrupts the insects' ability to sense human presence, thereby reducing their biting and feeding behavior. Additionally, DEET has been shown to bind to specific odorant binding proteins and receptors in certain mosquito species, further contributing to its repellent effects.

Pharmacodynamics

When used appropriately, DEET is designed for topical application on human skin to repel insects. At recommended doses, systemic absorption is minimal, which reduces the risk of toxicity. The repellent action primarily works by interfering with insects' sensory perception, leveraging the size and biological differences between humans and insects to create an effective barrier.

Pharmacokinetics

DEET is absorbed through the skin, but the extent of absorption is generally low when applied at recommended concentrations. It is metabolized in the liver, and its metabolites are primarily excreted in urine. The duration of action can vary based on the concentration of DEET used and the environmental conditions during application.

Adverse effects

• Skin irritation
• Allergic reactions
• Headache
• Nausea
• Dizziness

Precautions

• Use with caution in individuals with a history of skin sensitivities
• Avoid application on broken or irritated skin
• Keep away from eyes and mouth

Pregnancy

The safety of diethyltoluamide during pregnancy has not been fully established. Use only if necessary and after consulting a healthcare provider.

Breast-feeding

Caution is advised when using diethyltoluamide while breastfeeding. Consult a healthcare provider before use.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Formulations

• Topical solution
• Spray
• Lotion

Mechanism of action

The exact mechanism(s) of action by which both (a) insects are repelled by diethyltoluamide (DEET), and (b) humans can be affected deleteriously by exposure to toxic amounts of DEET have not yet been formally elucidated. Research is ongoing regarding the exact mechanism of action by which DEET is capable of repelling insects. However, the most longstanding mechanism proposes that the DEET chemical blocks the olfactory receptors of insects for the volatile 1-octen-3-ol compound that is an element in human sweat and breath. As a consequence, this proposed mechanism suggests that the blockade of insects' senses for this 1-octen-3-ol blinds and prevents the triggering of their biting and/or feeding instinct on humans and other animals that produce that compound. Nevertheless, this theory has not yet been fully elucidated. Furthermore, recent studies have demonstrated that DEET binds to certain molecular targets like the Anopheles gambiae odorant binding protein 1 (AgamOBP1) with high shape complementarity and the antennae-specific odorant receptor CquiOR136 of the southern house mosquito, Culex quinquefasciatus. In southern house mosquitos with reduced CquiOR136 transcript levels, behavioral tests demonstrated that this phenotype showed demonstrably lower responses/repulsion to DEET. Again, however, such findings require continued research and do not formally elucidate the mechanism of action by which DEET can repel insects. And finally, the mechanism of toxicity in which DEET is capable of eliciting effects of neurotoxicity in humans who have been exposed to toxic levels of the agent is also poorly understood. A recent study proposes that DEET is capable of blocking Na+ and K+ channels in the rat animal model. This ion channel blocking activity of DEET in neurons may subsequently contribute to the kind of neuro-sensory adverse effects like numbness experienced after inadvertent application to the lips or mouth of humans. Recent studies suggest that N, N-diethyl-meta-toluamide (DEET) is an acetylcholinesterase inhibitor and that this action may result in neurotoxicity and pose a risk to humans from its use as an insect repellent. We investigated the mode of action of DEET neurotoxicity in order to define the specific neuronal targets related to its acute toxicity in insects and mammals. Although toxic to mosquitoes (LD50 ca. 1.5 ug/mg), DEET was a poor acetylcholinesterase inhibitor (<10% inhibition), even at a concentration of 10 mM. IC50 values for DEET against Drosophila melanogaster, Musca domestica, and human acetylcholinesterases were 6-12 mM. Neurophysiological recordings showed that DEET had excitatory effects on the housefly larval central nervous system (EC50: 120 uM), but was over 300-fold less potent than propoxur, a standard anticholinesterase insecticide. Phentolamine, an octopamine receptor antagonist, completely blocked the central neuroexcitation by DEET and octopamine, but was essentially ineffective against hyperexcitation by propoxur and 4-aminopyridine, a potassium channel blocker. DEET was found to illuminate the firefly light organ, a tissue utilizing octopamine as the principal neurotransmitter. Additionally, DEET was shown to increase internal free calcium via the octopamine receptors of Sf21 cells, an effect blocked by phentolamine. DEET also blocked Na(+) and K(+) channels in patch clamped rat cortical neurons, with IC50 values in the micromolar range. These findings suggest DEET is likely targeting octopaminergic synapses to induce neuroexcitation and toxicity in insects, while acetylcholinesterase in both insects and mammals has low (mM) sensitivity to DEET. The ion channel blocking action of DEET in neurons may contribute to the numbness experienced after inadvertent application to the lips or mouth of humans.

Pharmacodynamics

When used appropriately, diethyltoluamide (DEET) containing products are designed to be applied directly to people's skin as a means to elicit a repelling action to keep insects from targeting human skin. At the amounts and doses recommended for use on human children and adults, noticeable absorption or systemic exposure is not expected. Owing to the proportional difference in size between humans and insects, however, the exposure of insects to the applied DEET (whether topically or via inhalation of DEET) is expected to be enough to interfere with the insects' sensory attraction to human skin.