Chemistry - An organophosphate insecticide, dichlorvos is also known as 2,2,-dichlorovinyl dimethyl phosphate or DDVP .
Storage/Stability/Compatibility - Dichlorvos tablets and capsules should be kept refrigerated (2-8°C). Dichlorvos feed additives should not be stored at temperatures below freezing. Dichlorvos is sensitive to hydrolysis if exposed to moisture and to oxidizing agents.
Pharmacology - Like other organophosphate agents, dichlorvos inhibits acetylcholinesterase interfering with neuromuscular transmission in susceptible parasites.
Uses/Indications - Dichlorvos is indicated for use internally in dogs and cats for the treatment of roundworms (Toxocara canis, Toxocara cati, Toxacaris leonina) and hookworms (Ancylostoma caninum, Ancylostoma tubaeforme, Uncinaria stenocephala). It is effective in swine against Ascaris, Trichuris, Ascarops strongylina and Oesophagostomum spp.. In horses, dichlorvos is labeled as being effective for the treatment and control of bots, pinworms, large and small bloodworms and large roundworms. It is also used as a premise spray to keep fly populations controlled and as a flea and tick collar for dogs and cats.
Pharmacokinetics - Specific information was not located for this agent.
Contraindications/Precautions/Reproductive Safety - Do not administer to horses suffering from heaves, colic, diarrhea, constipation, or infectious diseases until these conditions have been corrected. In dogs and cats, dichlorvos is contraindicated in animals exhibiting symptoms of severe constipation, intestinal impaction, liver dysfunction, circulatory failure, or to animals exposed to, or showing signs of infection. Dogs infected with D. immitis should not receive dichlorvos. Dichlorvos should not be used in conjunction with any other anthelmintics, taeniacides, filaricides (DEC exempted) or within a few days of other medications that inhibit cholinesterase (see drug interactions below). Studies performed in target species have demonstrated no teratogenic effects at usual doses.
Adverse Effects/Warnings - Adverse effects are generally dose-related and may include those listed below in the Overdosage/Acute Toxicity section. Cats, young animals, or debilitated animals may be more susceptible to toxic effects. Use in young kittens, cats with any other concurrent diseases or debilitated or animals otherwise stressed, should probably be avoided.
Overdosage/Acute Toxicity - If overdoses occur, vomiting, tremors, bradycardia, respiratory distress, hyperexcitability, salivation and diarrhea may occur. Atropine (see atropine and pralidoxime monographs for more information) may be antidotal. Use of succinylcholine, theophylline, aminophylline, reserpine, or respiratory depressant drugs (e.g., narcotics, phenothiazines) should be avoided in patients with organophosphate toxicity. If an ingestion occurs by a human, contact a poison control center, physician or hospital emergency room.
Drug Interactions - Acepromazine or other phenothiazines should not be given within one month of worming with an organophosphate agent as their effects may be potentiated. Because of its anticholinesterase activity, avoid the use of organophosphates with DMSO. Cythioate could theoretically enhance the toxic effects of levamisole. Pyrantel Pamoate (or tartrate) adverse effects could be intensified if used concomitantly with an organophosphate. Patients receiving organophosphate anthelmintics should not receive succinylcholine or other depolarizing muscle relaxants for at least 48 hours. Drugs such as morphine, neostigmine, physostigmine and pyridostigmine should be avoided when using organophosphates as they can inhibit cholinesterase.
Read and follow label directions, including any withdrawal times stated.
Monitoring Parameters - 1) Efficacy; 2) Adverse Effects
Client Information - Keep out of reach of children. Handling of dichlorvos liquid preparations (e.g., premise spray) must be done with extreme care; follow all label directions! Oral pellets are nondigestible and may be seen in the animals feces.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times -
Dichlorvos Oral: Tablets 10 mg, 20 mg; Capsules 68 mg, 136 mg, 204 mg; Pellets (in packets) 136 mg, 204 mg, 544 mg; Task® & Task® Tabs (Fermenta); (Rx). Approved for use in dogs (Capsules, Pellets and Tabs) and cats (Tabs Only).
Dichlorvos Oral Equine Wormer 78 g/pkt; Cutter Dichlorvos Horse Wormer® (Miles); (OTC)
Dichlorvos Feed Additives: Atgard® C (Fermenta); (OTC); Atgard® Swine Wormer (Fermenta); (OTC)
Also available in a 9.6% flea and tick collar for dogs and cats: Pet Insecticide Collar (Fermenta); (OTC) and a 40.2% concentrate for premise spraying in 5 gallon containers: Vapona® Concentrate (Fermenta); (OTC).
Human-Approved Products: None
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