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Information about CLASS ANTIHELMINTICS 4

Published on March 6, 2014

Author: raghuprasada


ANTI HELMINTICS: ANTI HELMINTICS Dr. RAGHU PRASADA M S MBBS,MD ASSISTANT PROFESSOR DEPT. OF PHARMACOLOGY SSIMS & RC. 1 Antihelmintics: Antihelmintics Drugs used to treat parasitic worm infections: helmintic infections Unlike protozoa, helminths are large and have complex cellular structures Drug treatment is very specific It is very important to identify the causative worm Done by finding the parasite ova or larvae in feces, urine, blood, sputum, or tissue HELMINTHS: HELMINTHS NEMATELMINTHS(ROUND) ROUND.W-ASCARIS.L HOOK W-NECATOR A WHIP W-TRICHURIS T THREAD W-STRONGYLOIDES.S PIN W-ENTEROBIUS V FILARIASIS-W BANCROFTI ONCHOCERCIASIS-O.VOLVULUS GUINEA W-DRACANCULUS M PLATYHELMINTHS TREMATODES-FLUKES BLOOD F-SCISTOSOMIASIS LIVER F-CLONORCHIASIS INTESTINAL F-FASCIOLOPSIASIS LUNG F-PARAGONIMIASIS CESTODES BEEF TW-T.SAGINAT PORK TW-T.SOLIUM FISH TW-DIPHYLLOBO THRIUM DWARF TW-HYMENOLEPIS.NANA LIFE CYCLE OF HELMINTHS: LIFE CYCLE OF HELMINTHS Classification : Classification Against Nematodes- ALBENDAZOLE, MEBENDAZOLE PYRANTEL PAMOATE, LEVIMASOLE, PIPERAZINE, IVERMECTIN, DIETHYLCARBAMAZINE, THIABENDAZOLE, DOXYCYCLINE Against trematodes METRIFONATE, OXAMNIQUINE, BITHIONOL, TRICLABENDAZOLE Against Cestodes NICLOSAMIDE Against trematodes and Cestodes - PRAZIQUANTEL Against Nematodes: Against Nematodes PYRANTEL PAMOATE MOA-Blocks acetylcholine at the neuromuscular junction, resulting in paralysis of the worms, which are then expelled through the GI tract P/K-small amount is absorbed, so high levels are achieved in intestinal walls  luminal helminths Uses –round w, hook w, Pin w—10mg/kg S/E-may cause hypersensitivity reactions, neurological symptoms (including “worm wobble”) and may precipitate epilepsy. Against Nematodes: Against Nematodes Benzimidazoles (ALBENDAZOLE & MEBENDAZOLE ) MOA-binds to beta tubulin prevents polymerisationbreak down of cytoplasmic microtubules they Inhibit uptake of glucose and other nutrients, depletion of glycogen stores decrease of ATP leading to autolysis and death of the parasitic worm Benzimidazoles -Pharmacokinetics: Benzimidazoles -Pharmacokinetics Mebendazole is absorbed after oral – 10% Fatty meal increases absorption  Albendazole , mebendazole It is rapidly metabolised , the products being excreted in the urine and the bile within 24-48 hours. Single dose for threadworm, BD daily for 3 days for hookworm and roundworm infestations. Thiabendazole is rapidly absorbed orally Albendazole is metabolised extensively by first-pass metabolism to the sulfoxide so has t1/2 -8-10 hrs Against nematodes: Against nematodes Benzimidazoles -ADR -Well tolerated, less side effects If used for >3months as in hydatid disease Epigastric distress, alopacia , insomnia, Teratogenic in animals Thiabendazole inhibits cellular enzymes of susceptible helminths. Inhibits the helminth -specific enzyme, fumarate reductase S/E- Gastrointestinal, neurological and hypersensitivity reactions, liver damage, and crystallurea may be induced. LEVAMISOLE: LEVAMISOLE It is effective in infections with the common round-worm as well as hook worm MOA: It has a nicotine-like action, stimulating and subsequently blocking the neuromuscular junctions. The paralysed worms are then expelled in the faeces . Ova are not killed. Phamacokinetics : The drug is given orally, is rapidly absorbed and is widely distributed. It crosses the blood-brain barrier. Side effects: They include gastrointestinal disturbances, Dizziness and skin eruptions. High concentrations can have nicotinic actions on autonomic ganglia in the mammalian host. There are some reports of encephalopathy Piperazine : Piperazine MOA-It reversibly inhibits neuromuscular transmission in the worm It probably by acting like GABA/GABA-gated chloride channels in nematode muscle. The paralyzed worms are expelled alive -used for Ascariasis -4g * 2 days and Pin worm- 4g * 7 days ADR- nausea, vomiting, rarely neurotoxic and allergic reactions nitrosamine metabolite-carcinogenic and teratogenic potential D/I- should not be used concurrently with pyrantel pamoate Ivermectin: Ivermectin It is highly effective broad-spectrum antiparasitic First choice of drug for the treatment of filarial infections and is very effective in onchocerciasis MOA: It kill the worm by opening glutamate-gated chloride channels (found only in invertebrates) and increasing Cl - conductance; by binding to a novel allosteric site on the acetylcholine nicotinic receptor to cause an increase in transmission, leading to motor paralysis; or by binding to aminobutyric acid receptors. Ivermectin: Ivermectin Uses : It has also given good results against W. bancrofti , which causes elephantiasis. A single dose kills the immature microfilariae of O. volvulus - river blindness The drug also has activity against infections with some roundworms: common roundworms, whipworms, and threadworms It works best if repeated at 6–12-month intervals. Side effects: skin rashes, fever, giddiness, headaches and pains in muscles, joints and lymph glands Diethylcarbamazine: Diethylcarbamazine Diethylcarbamazine is a piperazine deri . It is active in filarial infections caused by W. bancrofti It mainly act by make opsonisation of worm that detected by our immune system The drug is absorbed by oral administration and clear from body within 48 hrs Side effects Fever, headache, anorexia, malaise, urticaria , vomiting, and asthmatic attacks following the first dose are due to products of destruction of the parasite, and reactions are minimised by slow increase in dosage over the first 3 days. Against cestodes- NICLOSAMIDE: Against cestodes - NICLOSAMIDE MOA: Its action has been ascribed to inhibition of the parasite's mitochondrial anaerobic phosphorylation of ADP which produces usable energy The scolex and a proximal segment are irreversibly damaged by the drug The worm separates from the intestinal wall and is expelled There is negligible absorption of the drug from the gastrointestinal tract. Taenia solium , the drug is given in a single dose after a light meal, followed by a purgative 2 hours Unwanted effects are few, infrequent and transient. Nausea and vomiting can occur. NICLOSAMIDE: Adverse effects Drowsiness, dizziness, Malaise, anorexia, as well as gastrointestinal upsets. It is contradicted in pregnant women or nursing mothers. Drug interaction: Enzyme inducers dexamethasone , phenytoin, and carbamazepine increase metabolism Cimetidine , known to inhibit cytochrome P-450 isozymes , causes increased praziquantel levels. NICLOSAMIDE Against trematodes and Cestodes-PRAZIQUANTEL: Against trematodes and Cestodes -PRAZIQUANTEL PRAZIQUANTEL -It is the drug of choice for all forms of schistos and for cestode infections like cysticercosis . MOA: Permeability of the cell membrane to calcium is increased, causing contracture and paralysis of the both adult worms and larvae. Pharmacokinetics: It is rapidly absorbed after oral administration and distributes into the cerebrospinal fluid. S/E- It may cause nausea, headache, dizziness, and drowsiness; it cures with a single dose (or divided doses in one day). Against trematodes: Against trematodes METRIFONATE, OXAMNIQUINE, BITHIONOL, TRICLABENDAZOLE MIRTIFONATE –organophosphorus compound so is cholinesterase inhibitors. It is safe and coast effective for schistosoma infection.It has good oral absorption Orally active and t1/2 =1-5 hrs S/E-cholinergic side effects - diarrhoea , tremors, bronchospasm C/I- pregnancy Against trematodes: Against trematodes OXAMNIQUINE- tertahydroquinoline dervt Used against Scistosoma mansoni It is the drug of choice for all forms of schistosomiasis -given orally MOA- flukes esterifies drug to produce reactive metabolite that alkylates DNA of flukes. It intercalated with parasite DNA and inactivate it S/E- CNS-drowsiness, dizziness pruritis , urticaria Against trematodes: Against trematodes BITHIONOL- orally well absorbed DOC-for fascioliasis (sheep liver fluke) 30-50mg for 10-15 days on alternate days ADR- anorexia, nausea, vomiting avoided in children below 8yrs TRICLABENDAZOLE narrow spectrum benzimidazole DOC for treating human fasciola hepatica PowerPoint Presentation: Worms (helminths) Drug of choice Tapeworms (cestodes) Niclosamide or Praziquantel or Albendazole 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 Pyrantel Mebendazole or Pyrantel Mebendazole or Albendazole Mebendazole and Thiabendazole Thiabendazole Mebendazole or Pyrantel Mebendazole, Pyrantel, or Albendazole Ivermectin Diethylcarbamazine Flukes (trematodes) Schistzoma (Schistozomes) Praziquantel THANK YOU: THANK YOU

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