POSOLOGY PART- 2 VETERINARY DOSES

VETERINARY DOSES 

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A practicing pharmacist is considered to be responsible for supplying correct doses in any type of prescription.

Therefore it is required that he should have complete knowledge of posology which pretends to animal medication.

The doses require for animals are more or higher side is comparison to human beings because the weight and surface area are normally mentioned on body weights.

Doses are normally applicable to all species except in certain cases where it is specifically mentioned.

 

·     FACTORS INFLUENCING THE DOSES OF DRUG IN ANIMALS:

1. Age:

Young animals need less dose of a drug as compared to adults, because young animals are more susceptible to adults.

2. Sex:

Gender plays an important role while prescribing the dose for an animal. The female may require less dose than the male animals.

Certain drugs are contraindicated in pregnant animals because of hazards of inducing abortion. Some drugs have tendency to pass into milk which becomes unfit for human consumption. Such drugs must be used carefully when administered in milch animals. (milch animals- animals which produce milk fit for human consumption.)

3. Body weight and size:

The dose of drugs in case of animals depends upon animal weight and size. The size of animals varies according to its breed.

For example, in case of dogs, a which may be harmless for a heavy breed of dog may be dangerous for a lighter breed.

4. Time of administration:

A small dose may be more effective if given in an empty stomach rather than the same when given after meals.

Purgatives and anthelmintic are more effective when given empty stomach. Similarly, when hypnotics acts more accurately when given after sunset rather than early in the morning.

5. Route of administration:

The dose of same may varies with the use of different routes of administration. The maximum dose is required when drug is given orally.

Minimum drug is required when drug is given intravenous route.

The following route is observed when drug is delivered-

Oral > s/c > i/m > i/v

6. Environmental factors:

The atmospheric moisture and temperature plays an important role on tissues of animals.

In rainy season, when climate is quite hot and humid, less dose is required than in winter when climate is dry and cold.

7. Habit:

An animals which is constantly under the influence of a drug may develop tolerance for that drug.

In such animals the normal dose may fail to produce the desired effect. Hence, larger doses are required to produce the required effect.

8. Rate of elimination:

The rate of excretion of drug has marked effect on dose of the drug. The drugs which are excreted at faster rate  require larger doses than those drugs which are excreted at lower rate.

9. The effect of drug:

When two drugs having similar type of pharmacological effect are given in combination, the effect will become more powerful than the individual drug given in the combination.

 

10.     Purpose of medication:

The dose of drugs varies with the purpose of the drug for which it is used.

For example: magnesium sulphate act as purgative in large doses but in smaller doses it acts as an antacid.

11.     Species:

The dose of drug varies form species to species. The dose of drug for a cow will be different from horse, sheep, pig, cat, etc.

Opium is a narcotic even it produces excitement in horse but narcosis in dog.

Theses differences are due to anatomical and physiological peculiarities.

12.     Character of the drug:

Larger dose of drug are required if it is given in required.

For example, nux vomica powder is required to be given in larger doses than its active constituent strychnine alkaloid which is given in smaller doses.