Anthelmintic drugs_E.ppt

Assoc. Prof. Ivan Lambeve-mail: itlambev@mail.bgwww.medpharm-sofia.eu

Anthelmintic drugsAnthelmintic drugsInsecticidesInsecticides

(Abstract)(Abstract)

Relative Relative incidenceincidenceof helminthof helminthinfections infections worldwideworldwide

Niclosamide blocks glucose uptake by intestinaltapeworms. It may cause some mild GI symptoms.

Piperazine may cause hypersensitivity reactions,neurological symptoms (including “worm wobble”)and may precipitate epilepsy.

Praziquantel paralyses both adult worms andlarvae. It may cause nausea, headache, dizziness, and drowsiness; it cures with a single dose (or divided doses in one day).

Mebendazole blocks glucose uptake by nematodes. Mild GI distarbunces may be caused, and it should not be used in pregnancy or in children under the age of 2.

Albendazole is similar to mebendazole.

Levamisole paralyses the musculature of sensitive nematodes which, unable to maintain their anchorage, are expelled by normal peristalsis. It may cause abdominal pain, nausea, vomiting, headache, and dizziness.

Thiabendazole inhibits cellular enzymesof susceptible helminths. Gastrointestinal, neuro-logical and hypersensitivity reactions, liver damage,and crystalluria may be induced.Pyrantel depolarises neuromuscular junctionsof susceptible nematodes which are expelled in thefaeces. It cures with a single dose. It may induceGI disturbance, headache, dizziness, drowsiness,and insomnia.

Levamisole

Diethylcarbamazine kills both microfilariae andadult worms. Fever, headache, anorexia, malaise,urticaria, vomiting, and asthmatic attacks followingthe first dose are due to products of destruction ofthe parasite, and reactions are minimised by slowincrease in dosage over the first 3 days.

Ivermectin may cause immediate reactions due to the death of the microfilaria (early stage in the lifecycle of certain parasitic nematodes) . It can be effective in a single dose, but it works bestif repeated at 6–12-month intervals.

Cestodes (tapeworms)

Beef tapeworm – Taenia saginataPork tapeworm – Taenia soliumCysticercosis – Taenia soliumFish tapeworm – Diphyllobothrium latumHydatid disease – Echinococcus granulosus

Worms (helminths) Drug of choice Tapeworms (cestodes)Tapeworms (cestodes) Niclosamide or Praziquantel or

Albendazole

Roundworms (nematodes)Roundworms (nematodes)•Enterobius vermicularis (pinworm)•Ascaris lumbricoides•Trichuris trichiura (whipworm)•Trichinella spiralis (trichinellosis)

•Strongyloides stercoralis•Necator americanus (hookworm)•Ancylostoma duodenale

•Onchocerca volvulus (Onchocercosis)•Wuchereria bancrofti (Elephantiasis)

Mebendazole or PyrantelMebendazole or PyrantelMebendazole or AlbendazoleMebendazoleand ThiabendazoleThiabendazoleMebendazole or PyrantelMebendazole, Pyrantel, or AlbendazoleIvermectinDiethylcarbamazine

Flukes (trematodes)Flukes (trematodes)•Schistzoma (Schistozomes) Praziquantel

Enterobius vermicularisEnterobius vermicularis

Life cycle of Life cycle of Trichinella spiralisTrichinella spiralis (cosmopolitan) (cosmopolitan)

TrichinellaTrichinella larva larva encysted in a characteristic hyalinized capsule in striated muscle tissue

Life cycle of Necator americanusLife cycle of Necator americanus

AncylostomaAncylostomaduodenale duodenale

Elephantiasis (Lymphatic filariasis)Elephantiasis (Lymphatic filariasis) of the lower extremityof the lower extremity associated associated with with Wuchereria bancroftiWuchereria bancrofti infection infection

Life cycle of Life cycle of Taenia saginataTaenia saginata (beef tapeworm) (beef tapeworm)

Life cycle of Life cycle of Echinococcus granulosusEchinococcus granulosus

(small crustaceans)

Insecticides Insecticides Whereas fleas can be effectively dealt with bydisinfection of clothes, lice and mites requirethe topical application of insecticides to theinfected subject. Chlorphenothane (DDT – Dichlor-Diphenyl-Trichlorethan) killsinsects after absorption of a very small amount, e.g., via foot contact with sprayedsurfaces (contact insecticide).The cause of death is nervous systemdamage and seizures. In humans DDTcauses acute neurotoxicity only afterabsorption of very large amounts.

DDT is chemically stable and degraded inthe environment and body at extremelyslow rates. As a highly lipophilic substance, it accumulates in fat tissues.Widespread use of DDTDDT in pest controlhas led to its accumulation in foodchains to alarming levels. For this reason its use has now been bannedhas now been bannedin many countries.

Lindane is the active gama-isomer ofhexachlorocyclohexane. It also exerts aneurotoxic action on insects (as well ashumans). Irritation of skin or mucousmembranes may occur after topical use.Lindane is active also against intrader-mal mites (Sarcoptes scabieiSarcoptes scabiei, causativeagent of scabies), besides lice and fleas.It is more readily degraded than DDT.Permethrin, a synthetic pyrethroid, exhibits similar antiectoparasiticactivity and may be the drug of choicedue to its slower cutaneous absorption,fast hydrolytic inactivation, and rapidrenal elimination.

ScabieiScabiei