7: Pharmacology Flashcards
Define a drug
any substance or product that can alter function when entering the body.
Define pharmacodynamics
the drugs effect on the body
- mode of drug action
Define pharmacokinetics
the bodies effect on the drug
What are some of the sources drugs are derived from?
- Plants
- Animals
- Minerals
- Synthesised in labs
- Microorganisms
Name one drug developed from a fungus
penicilin
Name 2 drugs derived from plants
Morphine- poppy plant
Caffeine- caffea aravica plant
Name 2 drugs derived from animals
Adrenaline- adrenal glands of pigs, monkey and cows. Now synthesised artificially
- for treatment of anaphalcix
Insulin- from pigs and cows. Now synthesised artificially
- for treating diabetes
Describe the term “chemical name”
describes the chemical composition/molecular structure of the drug.
Describe the term “Generic name”
an abbreviated name given to the drug by the manufacturer that first develops the drug.
- This is a patient. The owner can only see the drug for a limited time by themselves before someone else is allowed to start making it.
- The cant sell it under he original name. (non-proprietary)
Describe the term “trade name”
or brand name is a generic name given by other companies for the same drug to market it. E.g. for paracetamol there is Panadol, Panamax, dymadon and tylenol.
What factors effect the choice of route of admission
- Physical properties e.g. solid, liquid, gas
- Chemical properties e.g. pH at site of action
- Other factors e.g. conscious state
What does the route of administration determine?
It changes how well the drug effects the body and does it job.
How quickly and easily it reaches its target.
how much reaches target
Name for swallowing a drug
oral route
Name for drug still undergoing 1st pass metabolism but not being swallowed e.g. via tube
enteral route
Mediums for oral administration
tablets
capsules
lozenges
liquid preparation
Advantages of oral (enteral) administration
economically benificial
non-invasive
pain free
easily administered if good patient compliance
good absorption along whole GI tract
Plasma concentration of drug does not increase to rapidly
Disadvantages of oral administration
requires patient compliance
patient must be concious and cooperative
may cause GI irritation
medication effectiveness may be altered by food, gastric secretions, emotional stress or physical activity.
Drug may denature in digestive tract (e.g. insulin is a protein and so acid would denature it so it isn’t given orally)
longer for drug to take effect
subject to first pass metabolism
Explain sublingual administration
under the tonged
- The network of capillaries just under the tonged facilitated quick absorption.
through cappillaries of mucosal membrane
avoids first pass metabolism
Explain buccal
placed between cheek and tongue
- capillaries in cheek absorb drug quickly
- But slower then sublingual as capillaries aren’t as close
through cappillaries of mucosal membrane
avoids first-pass metabolism
Describe the parenteral route
any non-oral method of drug administration
- Most commonly injections such as;
intravenous (IV) subcutaneous (SC) intramuscular (IM) - Also include; epidural and intra-arterial
Other placed that can be injected include
- Intra subarachnoid
- Intra plural
These are much less comon
Advantages of the parenteral route
- provides alternative to avoid disadvantages of oral admin
- IV and Intra-arterial= immediate onset
- IM and SC can be used to achieve slower or delayed onset of action.
- problems with compliance and cooperation can be avoided
- avoids first-pass metabolism
Disadvantages of the parenteral route
- requires skill to administer
- higher risk of infection
- onset of drug can be rapid
- painful
- requires accurate does
- more expensive
- may require additional; equipment
Describe the inhalation/pulmonary route
drugs administered by gas or fine mist
- lungs provide large surface area for absorption.
- lungs= rich capillary network
e. g. bronchiole dilators (asthma puffers)
Describe the topical route
applying drug to the skin or mucous membranes
- used to produce local or systemic effects
includes administration via skin, eyes, ears, nose, vagina and rectum.
- medication may take the form of an ointment, transdermal patch, drops, pessaries and suppositories
- must be applied to intact skin
What 4 factors influence how the drug reaches it molecular target.
influenced by how the drug is:
- absorbed into the body
- Distributed around the body
- Metabolised by the body
- Excreted from the body
Define drug absorption
process a drug takes to go from site of administration to the systemic circulation.
Intravascular admin= means drug skips many complication of absorption as it is injected straight into the blood stream.
Describe the absorption process of an oral drug (tablet in this case) that enters outside the bloodstream
- disintegrated (broken down)
- goes into solution (dissolution)
- is absorbed from the small intestine
- into the hepatic portal system (blood supply - liver)
- then into the systemic circulation
Factors affecting drug absorption
Formulation
- liquid > tablet (oral rouet)
Route of admin
- IV > tabet
Tissue surface area and thickness
>surface area= increased absorption and rate
Explain how the solubility of drug affects absorption
Lipid soluble drugs- easily cross membrane via simple diffusion- rapid absorption
Water soluble drugs- cross the membrane via facilitated diffusion or active transport- slower absorption
How can drugs be distributed?
Drugs can be distributed to both fluid and intracellular compartments throughout the body.
fluid compartment- in particular, blood
Intracellular compartments- target tissue plus other tissue e.g. bone and fat
- this can be both where we want and drug but also not where we want the drug.
Define distribution
process of reversible transfer of a drug between on location and another in the body.
Depending on the drug, the drug may;
- remain in the blood
- be distributed to organs that are well perfused (good blood supply)
- Be distributed more slowly to areas that are poorly perfused (e.g. adipose tissue)
What does the movement of drug to body tissue depend on?
- drug solubility (water or liquid soluble)
- cardiovascular functioning (especially cardiac output)
- perfusion of the area
(vascularity and permeability of capillaries) - pH of area
- Binding of drug to plasma protein