Important Terms in Pharmacology

What does a drug do to the body?
Pharmacodynamics refers to the relationship between drug concentration at the site of action and the resulting effect, including the time course and intensity of therapeutic and adverse effects. The impact of a drug present at the site of action is determined by that drug’s binding with a receptor. Receptors may be present on neurons in the central nervous system (i.e., opiate receptors) to depress pain sensation, on cardiac muscle to affect the intensity of contraction, or even within bacteria to disrupt the maintenance of the bacterial cell wall.

What body does to the drug?
Pharmacokinetics is the quantitative study of drug movement in, through, and out of the body. The intensity of the response is related to the concentration of the drug at the site of action, which in turn is dependent on its pharmacokinetic properties. Pharmacokinetic considerations, therefore, determine the route(s) of administration, dose, the latency of onset, time of peak action, duration of action, and frequency of administration of a drug. All pharmacokinetic processes involve the transport of the drug across biological membranes.

Use of drugs in the prevention & treatment of disease.
It is the application of pharmacological information together with knowledge of the disease for its prevention, mitigation, or cure. Selection of the most appropriate drug, dosage, and duration of treatment taking into account the specific features of a patient is a part of pharmacotherapeutics.

Clinical Pharmacology
The scientific study of drugs in humans.
Clinical pharmacology encompasses all aspects of the relationship between drugs and humans. It focuses on the safe, effective, and economic use of medicines. It is a diverse discipline that both sustains and advances the best healthcare.

The aspect of pharmacology deals with the adverse effects of Drugs.
Toxicology is the study of the adverse effects of chemical, physical, or biological agents on people, animals, and the environment. It involves observing and reporting symptoms that arise from exposure to toxic substances.
It also includes the study of adverse effects of drugs, since the same substance can be a drug or a poison, depending on the dose.

Pharmacodynamic Agents
Designed to have pharmacodynamic effects on the recipient.

Chemotherapeutic Agents
Designed to inhibit/kill parasites/malignant cells & does not have or with minimal pharmacodynamic effects in the recipient.

Orphan Drugs
Drugs or Biological Products for diagnosis/treatment/Prevention of a rare disease.
E.g.:- Liothyronine (T3), Desmopressin, Baclofen, Digoxin Antibody.

Routes of Drug Administration
Routes can be broadly divided into those for 
  1. Local action 
  2. Systemic action.
The local routes are:
  1. Topical
  2. Deeper tissues
  3. Arterial supply
The Systemic routes are:
  1. Oral
  2. Sublingual (s.l.) or buccal
  3. Rectal
  4. Cutaneous
  5. Inhalation
  6. Nasal
  7. Parenteral
  • Subcutaneous (s.c.)
  • Intramuscular (i.m.)
  • Intravenous (i.v.)
  • Intradermal injection

  • Intradermal: given into layers of skin. E.g.:- BCG vaccine, for testing drug sensitivity.
  • S.C: Only non-irritant drugs are given absorption can be enhanced by the enzyme Hyalurinase S.C.drug implants can act as depot therapy. E.g.:- steroid hormones. In children, saline is injected in large quantities – Hypodermalysis.
  • I.M: Mild irritants, suspensions & colloids can be injected by this route.
  • I.V: Directly to the vein.
  • Intraarterial: Only used for diagnostic studies. E.g.:- Angiograms, and embolism therapy.
  • Intrathecal: Spinal anesthetics into subarachnoid space.
  • Intra medullary: Drug introduced to Bone marrow.
  • Intraarticular & Intra tensional: Drug administered into joints. E.g.:- Hydrocortisone acetate in rheumatoid arthritis.

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