Pharmacology basics

Pharmacology  basics

This topics focuses on the fundamental principles of pharmacology. It also discusses the different routes by which drugs can be administered.
Kinetics, dynamics, therapeutics
This topics also discusses what happens when a drug enters the body. This involves three main areas:
     pharmacokinetics (the absorption, distribution, metabolism, and excretion of a drug)
     pharmacodynamics (the biochemical and physical effects of drugs and the mechanisms of drug actions)
     pharmacotherapeutics (the use of drugs to prevent and treat diseases).

How drugs are administered -

 The route will effect the quantity given and the rate at which the drug is absorbed and distributed in the body. These variables affect the drug’s action and the patient’s response.

Routes of administration include:
buccal, sublingual, translingual: certain drugs are given buccally (in the pouch between the cheek and gum), sublingually (under the tongue), or translingually (on the tongue)
gastric: this route allows direct instillation of medication into the GI system of patients who can’t ingest the drug orally
intradermal: substances are injected into the skin (dermis); this route is used mainly for diagnostic purposes when testing for allergies or tuberculosis
intramuscular: this route allows drugs to be injected directly into various muscle groups at varying tissue depths;
intravenous: the I.V. route allows injection of substances directly into the bloodstream through a vein;
oral: this is usually the safest, most convenient, and least expensive route; drugs are administered to patients who are conscious and can swallow
rectal and vaginal: suppositories, ointments, creams, gels, and tablets may be instilled into the rectum or vagina to treat local irritation or infection; some drugs applied to the mucosa of the rec- tumour vagina can be absorbed systemically
respiratory: drugs that are available as gases can be administered into the respiratory system; drugs given by inhalation are rapidly absorbed, and medications given by such devices as the metered-dose inhaler can be self-administered, or drugs can be administered directly into the lungs through an endotracheal tube in emergency situations
subcutaneous (subQ): with the subQ route, small amounts of a drug are injected beneath the dermis and into the subcutaneous tissue, usually in the patient’s upper arm, thigh, or abdomen
topical: this route is used to deliver a drug through the skin or a mucous membrane; it’s used for most dermatologic, ophthalmic, otic, and nasal preparations.
Drugs may also be given as specialized infusions injected directly into a specific site in the patient’s body, such as an epidural infusion (into the epidural space), intrathecal infusion (into the cerebrospinal fluid), intrapleural infusion (into the pleural cavity), intraperitoneal infusion (into the peritoneal cavity), intraosseous infusion (into the rich vascular network of a long bone), and intraarticular infusion (into a joint).

Pharmacokinetics:

Absorption:


Drug absorption covers a drug’s progress from the time it’s admin- istered, through its passage to the tissues, until it reaches systemic circulation.
On a cellular level, drugs are absorbed by several means—primarily through active or passive transport.

Distribution:

Drug distribution is the process by which the drug is delivered from the systemic circulation to body tissues and fluids. Distribution of an absorbed drug within the body depends on several factors:
    blood flow
    solubility
    protein binding.

Metabolism:

Drug metabolism, or biotransformation, is the process by which the body changes a drug from its dosage form to a more water-soluble form that can then be excret- ed. 
Drugs can be metabolized in several ways
    Most drugs are metabolized into inactive metabolites (products of metabolism), which are then excreted.
    Other drugs are converted to active metabolites, which are capable of exerting their own pharmacologic
action. Active metabolites may undergo further metabolism or may be excreted from the body unchanged.
   Some drugs can be administered as inactive drugs, called a       pro- drugs, which don’t become active until they’re metabolized.

Excretion:



Drug excretion refers to the elimination of drugs from the body. Most drugs are excreted by the kidneys and leave the body through urine. 

Drugs can also be excreted through the lungs, exocrine (sweat, salivary, or mammary) glands, skin, and intestinal tract.

Pharmacodynamics:

It is the study of the drug mechanisms that pro- duce biochemical or physiologic changes in the body.
The inter- action at the cellular level between a drug and cellular compo- nents, such as the complex proteins that make up the cell mem- brane, enzymes, or target receptors, represents drug action. The response resulting from this drug action is the drug effect.

Pharmacotherapeutics :

It is the use of drugs to treat disease. When choosing a drug to treat a particular condition, health care providers consider not only the drug’s effectiveness but also other factors such as the type of therapy the patient will receive.

 For more information on Pharmacology visit here: https://www.pharmaeducator.com/


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