PHARMACOLOGY
UNIT ONE (1)
DEFINITION:
Pharmacology is science of the drug????It is the science that deals with the mechanism of action, uses, adverse effects, and fate of drugs in animals and humans.
Drug: any chemical agent which effects any biological process
medicines are drugs used to prevent or treat disease
SOURCES OF DRUGS
- Minerals: Liquid paraffin, magnesium sulfate,.
- Animals: Insulin, antitoxin sera, etc.
- Plants: Morphine, digoxin, etc.
- Synthetic source: Aspirin, sulphonamides.
- Micro organisms: Penicillin, streptomycin and many other antibiotics
- Genetic engineering: Human insulin, human growth 6
hormone etc.
DRUG NAMES
Drug is given three names. Each is used in a different area of the drug industry.
1. Chemical Names
2. Generic/Non-Proprietary/Official Names
3. Brand/Trade/ Proprietary Names
Ycal structure of the drug.
Chemical names: describes the chemical structure of the drug.
Not commonly used b/c of their complexity
It is important to chemists, pharmacists, and researchers who
work with drugs at the chemical level. E.g. N-(4-hydroxyphenyl) acetamide
Generic Name: is the universally accepted name.
It is the approved official non-proprietary name for the drug.
The generic name appears on all drug labels and is used in any country and by any manufacturer.
Each drug has only one generic name.
E.g. Acetaminophen, paracetamol
Brand Name: is the name given by manufacturers
It is the name in which drug companies often select and
copyright.
One drug may have multiple proprietary name
E.g. Tylenol, panadol
2. PHARMACOKINETIC
What the body does to the drug- refers to the study of how the body processes drugs
It includes the 4 basic components of : 1# Absorption
2# Distribution
3# Metabolism (Biotransformation)
4# Excretion
BIOAVAILABILITY
“Bioavailability is the proportion of the administered dose that reaches the systemic circulation.”
HALF LIFE OF DRUGS
Drug excretion is commonly expressed in terms of half life (t1/2)
This is the time required for the concentration of the drug in the plasma to decrease by one-half of it’s initial value
Drug half life is variable and can be long or short
PHARMACODYNAMIC
What a drug does to the body- refers to the study of the mechanism of drug action on living tissue.
TYPES OF DRUG-RECEPTOR INTERACTIONS
Main types of action at receptor:
Receptor agonists
Receptor antagonists
Agonists: Drug that has the ability to produce a desired therapeutic effect when bound to the receptor.
Antagonists: Drugs that bind well to the receptor but produce no receptor response. This can prevent other drugs from having an effect, thus they are called blockers.
Onset of drug action is the time it takes after the drug is administered to reach a concentration that produces a response.
Duration of action is the time during which the drug is present in a concentration large enough to produce a response.
Peak effect is the time it takes for the drug to reach its highest effective action.
THERAPEUTIC RESPONSES
Toxicity studies of drugs determine two dosage levels for drugs.
The effective dose(ED) is the dose of a drug necessary to produce the desired intensity of effect in one-half of all patients.
The lethal dose(LD) is the dose of a drug that elicits an undesirable toxic or lethal reaction in one- half of all patients
THERAPEUTIC INDEX(TI)
TI= LD/ED
A drug with a wide therapeutic index has a high safety margin and is relatively safe; the lethal dose is greatly in excess of the therapeutic dose.
A drug with a narrow therapeutic index is more dangerous for the patient because small increases over normal doses may cause toxic reactions.
Loading doses: higher amount of drug given once or twice to achieve maximum effective dose quickly
Maintenance dose: intermittent doses given to maintain plasma levels
DEFINITION OF TERMS
Affinity: ability of drug to bind to receptor,
Potency: shows relative doses of two or more agonists to produce the same magnitude of effect,
Efficacy: a measure of how well a drug produces a response (effectiveness)
4.ADVERSE DRUGR REACTIONS(ADRS)
Definition
An adverse drug reaction (ADR) (also called an adverse drug event (ADE) can be defined
as (WHO def.) unintended and noxious (harmful) response that unintended and noxious (harmful) response that occurs at normal doses of the drug used for
prophylaxis, diagnosis and treatment of
diseases)’.
Generally the causality of adverse drug
reactions is uncertain, making it more
accurate to refer to ‘suspected ADRs’.
Adverse Effects: are unwanted and unpredictable action of the drug.
Side Effects: unwanted but predictable and unavoidable effects of a drug.
Toxic effect- Are high single doses or long-term therapy leading to high cumulative doses.
){kind=link}
0 Comments