Pharmacodynamics

Pharmacodynamics

It covers all the aspects relating to “what the drug does to the body”. It is the study of biochemical and physiological effects of drug and their mechanism of action at organ level as well as cellular level.

Types of Drug Action:

Different types of drug actions are follows:

Stimulation: Some drugs act by increasing the activity of specialised cells, eg., catecholamine stimulate heart to increase heart rate and force of contraction.

Depression: Some drugs act by decreasing the activity of specialised cells, eg., general anaesthetics depress the central nervous system.

Irritation: Certain drugs on topical application can cause irritation of the skin and the adjacent tissues, eg., eucalyptus oil.

Replacement: When there is a deficiency of endogenous substances, they can be replaced by drugs, eg., Insulin.

Chemotherapeutic: Drugs are selectively toxic to infective organism or cancer cells, eg., antibiotics, anticancer drugs.

Effects of Drugs on the Body

THERAPEUTIC EFFECTS: It is the expected or predictable physiological response of medication. The drugs are administered for the following purpose.

1.        TO PROMOTE HEALTH;- Drugs are given to the individual to increase the resistance against diseases (e.g. vitamins).

2.        TO PREVENT DISEASES;- (e.g. vaccines and anti-toxins).

3.        TO DIAGNOSE DISEASE:- (e.g. barium used in the X-ray studies).

4.        TO ALLEVIATE DISEASES:-Certain drugs are given for the palliative effect or for the temporary relief of distressing symptoms but does not remove the cause or cure the disease (e.g. analgesics)

5.        TO TREAT OR CURE A DISEASE:-

·           By restoring normal functions (e.g. digoxin).

·           By destroying the causative organisms (e.g. quinine in malaria.)

Local and Systemic effects

Local effects of a drug are expected when they are applied topically to the skin or mucus membrane.

A drug used for systemic effect must be absorbed into the blood stream to produce the desired effects in the various systems and parts of the body.

Adverse effects

Adverse effect is any effect other than the therapeutic effect. These are generally considered severe responses to medication.

Side effects

Side effect are the minor adverse effects side effects can harmful or harmless.

Allergic Reactions

A client can react to a drug as a foreign body and thus develop symptoms of allergic reaction. Allergic reaction can be either severe or mild. A severe allergic reaction usually occurs immediately after the administration of the drugs it is called anaphylactic reaction. A mild reaction has a variety of symptoms. From skin rashes to diarrhoea. Such as:

SKIN RASHES: (urticaria) Oedematous pink-ish elevation with itching .

PRURITIS: Itching of the skin with or without a rash.

RHINITIS: Excessive watery discharge from the nose.

LACRIMAL TEARING: Excessive tears from the eyes.

Proven Human Teratogens: