Pharmacodynamics of Drugs
Pharmacodynamics is the branch of pharmacology concerned with
the effects of drugs and the mechanism of their action.
Pharmacodynamics refers to the study of molecular, biochemical, and physiological effects of drugs, action, or effects of drugs in the body.
The difference between Pharmacodynamics and Pharmacokinetics
is, Pharmacodynamics is the study of
what a Drug Does to the Body, and Pharmacokinetics of drug is the study of what the Body does to
the Drug.
For example,
1. Aspirin acts by
irreversibly inhibiting the enzyme “prostaglandin synthetase” thus preventing
inflammatory response.
2. Antibiotics Drug
Treat infection.
Pharmacodynamics of Antibiotics Drugs
Pharmacodynamics of Antibiotic
drugs act by-
1. Kill bacteria
2. Inhibition of enzymes
that are involved in cell wall biosynthesis
3. Inhibit the synthesis of
protein
4. Inhibit nucleic acid
synthesis, metabolism, and repair
5. Inhibit their growth or
reproduction (DNA replication)
Drug Action - Action of Drugs
1. Desirable effect
Therapeutic action, treatment, prevention
2. Undesirable effect
Adverse/side effects, vomiting, toxicity
Drug Act on Body
Drug act on body by-
1. Stimulation
Increase physiological activity.
2. Depression
Suppress the physiological activity.
3. Irritation
4. Replacement
5. Anti-infective and sterilization
6. Cytotoxic action
7. Modification of immune status
Vaccines and sera.
Site of Drug Action
1. Local action
Drug applied directly to the area; site of application that
needs treatment.
Example: Topical the drug, Eardrop, topical skin creams or
ointments
2. Systemic action or general action
A drug used in the treatment affects the body or acts on systems that involve the entire body.
Such as respiratory, cardiovascular, gastrointestinal, nervous
systems.
In which drug is absorbed and distributed from the site of administration.
For example- Oral Aspirin
3. Remote or
Reflex action
The reflex action of a drug refers to drug acts on site and provokes
effect away from site action.
For example,
1. Action of Apomorphine
injection into the arm stimulates or provokes the brain vomiting center.
2. Action of Adrenalin
provoked a rise of arterial pressure and stimulation of respiration.
What are 10
rights of Medication
Administration, check out here?
Mechanism of Drug Action
The basic mechanism of drug maybe -
1. Through drug-receptor
Agonist/ Antagonist.
2. Through enzyme and pump
Hydrogen pump,
Potassium pump); inhibit or stimulate.
3. Through ion channel
Such as Na+ channel, K+ channel, Beta Channel.
4. By physical action
Absorption; a radioactive substance.
For example, I-131
5. Chemical Interaction
Chemical interaction, for example, Antacids reduce the
secretion of HCL in the Stomach.
6. Altering Metabolic Process
7. Carrier molecule
Factors that Modify the Effect of Drug
1. Patient Factor
1. Bodyweight
2. Age
3. Sex
4. Species
5. Diet and environment
6. Genetic Factor
7. Disease condition
5. Psychological Factor
2. Drug Factor
1. Route of Drug Administration
Check out her different routes of drug administration.
2. Dose
3. Repeated dose
4. Presence of other Drug
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