After reading this article you will learn about the drugs used against protozoal diseases.
Drug Used Against Trypanosomiasis:
Diamidines:
It has found to have trypanocidal activity due to the guanyl organic group NH: C(NH2)
The presence of two guanyl organic group and separated by a paraffin hydrocarbon chain is found to give a high trypanocidal effect.
As the length of the paraffin chain increases the trypanocidal effect increases and reaches maximum at undecane diamidine.
1. These compounds possess activity against other protozoa like Babesia.
2. It has some antibacterial activity similar to sulphonamides.
3. Diamidines produces toxic effects on the kidney and liver.
4. Eg: Phenamidine, propamidine, Stilbamide, Diminazene, Pentamidine (n = 5)
5. Diamidines have been used either as free bases or as one of the three salts:
i.e. Di-hydrochloride
Di-methyl-sulphonate
Isethionate
The action and uses of the most important compound, Diminazene aceturate is discussed below:
Diminazene Aceterate:
1. Diminazene aceturate is an odourless yellow powder relatively soluble in water and only slightly soluble in organic solvent.
2. As trypanocide, it is effective against T. vivax, T. congolense and less effective against T. brucei.
3. As babesicidal
4. As bactericidal (Mainly Brucella and Streptococcus sp.)
Dosage:
For Babesia:
Single dose @ 3.5 mg/kg body wt., in horses, cattle, sheep and dogs, deep I/M.
For Trypanosoma:
Single dose @ 3.5 mg/kg body wt. for T. vivax and T. congolense but for T. brucei infection and resistant cases, dose may be increased to 7 mg/kg.
Aminophenanthridium compounds:
The main preparation in use are the dimidium, homidium and pyrithidium bromides.
Dimidium Bromide:
The chemotherapeutic action of the phenanthridium compounds is believed to be due to interference with cell division. It is effective against T. Congolense, less effective against T. vivax and inactive against T. brucei and T. evansi.
Dose:
Horse and cattle 1 to 1.5 mg/kg b.w as 1% aq. solution by deep I.M. route.
Homidium Bromide:
It has greater trypanocidal action than dimidium against T. congolense, T. vivax. It has some activity against T. brucei but like dimidium it is inactive against T. evansi.
Dose: 0.25 to 1 mg/kg b.w. as 1% aqueous solution by deep I.M. route.
Pyrthidium-Bromide: It is used as prophylatic against T. congolense, T. vivax and T. brucei.
Dose:
2 mg/kg b.w. as 1 to 2% aqueous solution by deep I.M.
Quinapyramine Compounds:
There are two quinapyramine compounds in use:
(a) The Sulphate:
It is rapidly absorbed and has mainly trypanocidal action with low prophylactic value.
(b) The Chloride:
It is slowly absorbed and has a strong prophylactic action.
Combined sulphate and chloride compound are available commercially. These compounds are used extensively for trypanosome therapy and prophylaxis.
The mixture is available in powder form in the ratio of 3: 2 (Sulphate: Chloride). The combination is administered by S.C. at the rate of 0.025 mg/kg b.w.
Quinapyramine is active against T. congolenes T. evansi and T. Vivax, T. equiperdium and T. equinum. T. brucei is less susceptible to Quinapyramine.
It should be administered as 10% aq. solution, S.C., except in horses where sloughing can occur, it is advisable to inject 5% solution I.M. or to divide the dose into two or three injection (all different sites).
Toxicity:
Toxicity is noticed in young animals where trembling, sweating and salivation occurs if quinapyramine used in higher dosage.
Suramin:
It is effective against T. evansi in horses, camels, cattle and dogs, T. brucei in horses and dogs, T. equinum (causes Mai de Caderas) and T. equiperdum (causes Dourine) in horses.
Dose: 7-10 mg/kg body wt.
Camel: 8-12 mg/kg body wt.
Cattle: 12 mg per kg body wt.
It should be administered as 10% aqueous solution I.V.
Antimony and Potassium Tartrate: (Tartar emetic)
Sodium salt is more safe than potassium salt.
Dose:
Horse – 3-5 mg/kg b wt. (20% soln)
Cattle – 3-5 mg/kg b wt. (20% soln)
Dogs – 1-3 mg/kg b wt. (20% soln)
Cats – 1-3 mg/g b wt. (20% soln)
It should be administered strickly as 20% aqueous solution by slow I.V. route.
Other drugs like Trypan blue, Trypan red and Stilbophen are neither safe nor effective as the modern drugs.
Drug Used Against Babesiasis:
Diamidines (Diminazene aceturate):
The antitrypanosidal use of this drug has already been discussed.
The use of diminazene against different babesia are as follow:
Amicarbalide Isothionate:
This drug is effective against Babesia diver gens, B. bovis, B. bigemina, B. argentina and B. Cabolli: It is not much effective against B. Canis. It is also not effective against Theileria parva.
Dosage:
5 to 10 mg/kg by I.M. S.C. or I.M. route.
Imidocarb Dipropionate:
This drug is recommended for the treatment and prophylaxis of Babesiosis and Anaplasmosis.
Dosage:
Cattle: 1.2. mg/kg b.wt., S.C., I.M. (Babesiosis)
3 mg/kg b.wt. S.C., I.M. (Anaplasmosis)
Horses 2.4 mg b.wt.S.C., I.M. (Anaplasmosis)
Dogs 6 mg b.wt. S.C., I.M. (Anaplasmosis)
The safety margin of imidocarb is not very high as it may cause death in cattle when used as 10 mg/kg b.wt.
Quinuronium Sulphate:
This drug is used against B. cabelli, B. bovis, B.bigemina, B. moteri, B. suis, B. canis. It cures the disease in 24- 48 hrs. if used early, sometimes drugs can be repeated next day after second dose it should not been repeated for the period of 3 months due to chance of severe shock and death in animals.
It should be administered as 5% solution S.C. in horse, cattle and pig. For dogs and sheep it should be diluted 10 times further (i.e. 0.5% solution) for administration by S.C. injection.
Toxic reaction may occur in animals with symptoms like tremer, salivation, urination and defaecation, within 6-10 hrs. of administration.
Trypan Blue:
This drug was used against the Babesia earlier but is ineffective against B. equi, B. bovis or B. gibsoni and also stains tissue and secretions, therefore not in use now.
Dosage:
The drug should be used as 1-2% solution.
Tetracycline:
Dog:
Doxycycline at 10 mg/lkg b.w. twice daily for 11 days is effective against Babesia canis.
Drugs Used Against Theileriesis:
Buparvaquone:
2-trans (4-f-butyl cyclohexyl) methyl-3-hydroxy- 1, 4- nephthoquinone chemically it is.
Buparvaquone acts on the macro schizonts and intiaerythrocytic piroplasms.
Dose: 2.5 mg/kg b.wt., i.m. 1 to 2 treatments.
Tetracycline:
Tetracycline can be used to treat Theileria infection in cattle. The effectiveness of tetracycline against theileria is less and must be used in large dose early in infection for longer period of time.
Drugs Used Against Histomoniasis:
Nitrothiazole:
This drug is used against black head (histomoniasis) in turkey (Histomonas meleagridis). It is used both therapeutically and prophylactically.
Dosage:
Treatment – 0.1% for 14 days in feed.
Prophylaxis – 0.05% (feed) or 0.03% in water for 20 weeks.
Individual treatment – 100 mg capsule/bird.
Dimetridazole:
This compound is used prophylactically and therapeutically against black head in Turkey and chickens.
Dosage:
0.0125 – 0.015% w/w (feed) Prophylactic in Turkey
0.05% w/w for 7-14 days Treatment in Turkey/Chicken
0.0075% w/w (feed) Prophylactic in chicken
Drugs Used Against Coccidiosis:
Sulphonamides:
Sulphonamides were the first anti-coccidial and are used as either coccidiostatic or coccidiocidal. It is mostly active against the asexual stages (not very active against early asexual stage) and lesser activity against the sexual stages of coccidia.
Sulphaquanidine, Sulfadiazine, sulfadimine, sulfamethoxazole and sulfaquinoxaline. Because of the development of more potent and less toxic drugs, the use of sulphonamide in the treatment of poultry coccidiosis is decreasing. It is still used in treatment of coccidiosis in dogs, cats, rabbit and ruminants.
Sulphaquinoxaline:
Amprolium:
Amprolium is structurally related to thiamine, therefore competitively inhibits the active transport of thiamine. Its action on the parasite is 50 times greater than the host. It act mainly on first generation schizont and has some activity against larval stage and the sporulating oocyst. It is therefore, mainly used as prophylactic.
Dosage:
Chickens: 125-500 PPM continuously in feed
Cattle: 5 mg/kg in water for 21 days (Preventive), 10 mg/kg in water for 5 days (curative)
Ionophores:
This group of anti-coccidial are widely used at present time. In addition to anti-coccidial property, ionphores have growth promotional properties, for which they are exclusively used in cattle. It mainly acts by interfering the transportation of ions through the membrane, thus disrupting the cellular reactions of the cells.
Its activity is directed against sporozoites and merozoites, thus for better result it has to be fed continuously at recommended dosage/ionophores have a low therapeutic index and are highly toxic in horses (lethal at 2-3 mg/kg). It should not be given to animals treated with tiamulin within 7 days.
Examples are:
Drug Used Against Amoebiasis and Giardiasis:
Metronidazole:
Metronidazole has potent amoebicidal activity against – E. histolytica, Trichomonas giardia (Trophozoite). It is well absorbed from the intestine and has excellent tissue concentration and therefore active against both luminal and extra luminal protozoa.
It is also active against anaerobic cocci, both anaerobic gram negative bacilli and anaerobic spore forming gram positive bacilli. It is also effective against Helicobacter, which is responsible for gastritis in animals and man.
Dosage:
Bovine genital Trichomoniasis: 75 mg/kg, I.V., Daily for 3 days.
Giardia (Dog): 15-30 mg/kg b.w. twice daily for 5-7 days.
Foal: 5 mg/kg b.w. thrice daily for 10 days.