DECTOMAX

Indications

• Nematode infections
• Arthropod infestations
• Gastrointestinal roundworms
• Lungworms
• Ectoparasitic infestations

Dosage

Children: Refer to BNF for Children for appropriate pediatric dosing recommendations.

Adults: Refer to BNF for specific dosing guidelines.

Mechanism of action

Doramectin induces rapid, non-spastic paralysis in nematodes and arthropods by modulating trans-membrane chloride ion (Cl-) channel activity. It activates Cl- channels in the nerve and muscle cells of these parasites, leading to increased Cl- conductance, altered membrane potential, and inhibition of electrical activity. While doramectin has intrinsic activity on mammalian GABA receptors, its poor penetration of the blood-brain barrier contributes to its safety profile in mammals.

Pharmacodynamics

The pharmacodynamic effects of doramectin are primarily related to its action on the nervous system of parasites. By enhancing the conductance of chloride ions, doramectin causes hyperpolarization of the nerve and muscle cells in parasites, resulting in paralysis and eventual death. The selectivity for parasitic over mammalian systems is attributed to the limited central nervous system penetration.

Pharmacokinetics

Doramectin is well-absorbed following administration and distributes widely in body tissues. Its elimination half-life varies depending on the species and administration route, with a longer duration of action observed in target parasites. Metabolism occurs primarily in the liver, with excretion mainly via feces. Due to its lipophilic nature, doramectin tends to accumulate in fat tissues, leading to prolonged effects against parasites.

Adverse effects

• Hypersensitivity reactions
• Neurological effects (e.g., tremors, ataxia)
• Gastrointestinal disturbances (e.g., vomiting, diarrhea)
• Dermatological reactions (e.g., pruritus, rash)

Precautions

• Use with caution in animals with known hypersensitivity to avermectins
• Not recommended for use in breeding, pregnant, or lactating animals due to potential risks

Pregnancy

Safety in pregnant animals has not been established; use only if benefits outweigh risks.

Breast-feeding

Safety in lactating animals has not been established; use only if benefits outweigh risks.

Storage

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

Formulations

• Injectable solution
• Oral solution
• Topical formulation

Mechanism of action

Avermectins induce rapid, non-spastic paralysis in nematodes and arthropods. One common feature of avermectins appears to be the modulation of trans-membrane chloride ion (Cl-) channel activity in nematode nerve cells, and in both nerve and muscle cells of arthropods. These Cl- channels may be gated by a variety of neurotransmitter receptors including gamma-aminobutyric acid (GABA), glutamate and acetylcholine. Activation of the Cl- channels by avermectins leads to an increase in Cl- conductance which results in a changed membrane potential and this causes inhibition of electrical activity in the target nerve or muscle cell. GABA is also a major inhibitory neurotransmitter in the mammalian CNS and avermectins do have intrinsic activity on the mammalian GABA receptor/Cl- channel complex. Avermectins have been reported to bind to glycine receptor/Cl- channel complexes which are restricted to the CNS in mammals. Penetration of the blood brain barrier by avermectins is extremely poor and this may account for the wide margin of safety exhibited by these compounds following administration to mammals. /Avermectins/