Pharmacology Flashcards
Directly related to section X of assessment
section 2! 20%
Medicines management - Definition and Reference
How common are medication errors?
A term defined by the UK’s Medicines and Healthcare Products Regulatory Agency (MHRA) as:
“The clinical, cost-effective and safe use of medicines to ensure patients get the maximum benefit from the medicines they need, while at the same time minimising potential harm.”
Medication errors are second most reported accident
Accountability? 2 x ref
Legal Accountability - medicines Act
Trust Policy / Employment - NMC as regulator
Medication Legistlation
Medicines Act 1868
Misuse of Drugs Act 1971
Safe custody act
What Medicines Management legislation is there?
Used to be NMC The Standards of Medicines Management 2007… (lots of things covered by NMC code of conduct)
…withdrawn in Jan 2019.
Replaced with:
Royal Pharmaceuticals Society’s:
- A competency framework for all Prescribers
NMC:
- Standards for Prescribing Programmes
What Medicines Management legislation in healthcare settings is there?
Professional Guidance on the Administration of Medicines in Healthcare Settings - Royal Pharmaceutical Society
NMC Code relating to medicines?
- 2 Manintain the knowledge and skills you need for safe and effective practice
- 5 Complete the necessary training….
18.2 keep to appropriate guidelines when giving advice on using controlled drugs…
….Many many
Aspects of Professional Practice
Recognition of role and responsibilities
Level of knowledge and experience…
What factors affect drug administration?
Age Weight Underlying disease / pathology Amount of drug given Absorption and excretion rate
Most drugs have 3 x names
Generic
Brand
Chemical
Pharmacology
Pharmakon - drug
ology - the study of
Looks at composition, effects and uses of drugs
Drug
Any chemical which affects living organism
Pharmacodynamics
Action of drug - qualitatively and quantitatively
Mechanism which drugs have on body -
Receptor Theory - what is it?
Lock and Key mechanism
Signal Pathway
e.g. how does adrenaline increase your heart rate
Signal molecule (ligand) Receptor Intra-cellular signal Target protein Response
Adrenaline is key, lock is?
Alpha and beta receptors in the heart
Receptors
Glycoproteins that recognise and bind to ligands (e.g. adrenaline)
Ligands are smaller molecules which can attach to
Receptors change their shape in response to
signalling molecule Binding to receptor -?
Changes the shape of the receptor
Generates biochemical reactions inside the cell (Signal Transduction) leading to several reactions called ‘secondary messengers’ that is eventually translated into a biological response (e.g. muscle contraction, hormone sectretion)
The more receptors involved, the bigger the response
Pharmacokinetics
Movement of drugs inside the body.
ADME - Absorption, distribution, metabolism and excretion
ADME
Absorption
Distribution
Metabolism
Excretion
Drug absorption
Most drugs given orally
In most routes absorption has to happen for the drug to access body compartments
Exceptions are parental routes
Drugs have to cross membranes to gain access
chemical nature determines how absorption can occur
Name as many routes of administration
Sublingual Oral Intramuscular Intravenous (quickest) Ocular Subcutaneous
Absorption - Active Transport
Requires ATP to move drug from lower concentration to a higher concentration. Moves across cellular barriers against the concentration gradient.
Absorption - Passive Diffusion
Moves from higher concentration to lower concentration
What other drug factors impact absorption of drugs?
Chemical size
pH
Solubility of drug
Surface area for absorption (e.g. villi/microvilli of intestinal tract)
Vascularity
Presence or absence of food in stomach
Presence of enzymes, acidity, bacteria etc
Most drugs are distributed by:
Diffusion - drug state must allow for this
Adolf Fick
Drug distribution
Small molecules absorbes easier
Acid drugs in acid medium
Base drugs in base medicum
Cell membranes are mainly lipid (fatty) materials - only lipid-like substances (lipophilic) substances cross easily ad rapidly
Most drugs act on receptors - typically protein
Distribution
Blood-tissues - depends on?
Factors needed for absorption
Affinity to bind with carrier/buffer proteins e.g. albumin and globulin-saturation-buffer
MORE MISSED
Metabolism
Drug metabolising enzymes have evolutionary defense
CYP450 and enzymes - make drugs water soluable to be excreted in urine
Chemical modifications increase / decrease pharmacological activity and or half life
Routes of elimination
Hair Saliva Milk Sweat Skin Alveolar Bilary- ? Renal Faecal
Agonist
e.g. drug?
When a drug stimulates a receptor
Binds to receptor protein
Produce confirmational change
Enhance biological response
e.g. adrenaline acts on beta 2 receptors in lungs, bronchodilator
Antagonist
e.g. drug?
When a drug blocks a receptor
Binds to receptor
No confirmational change to initiate intracellular signal.
Morphine activates morphine receptors -kappa delta receptors
Naloxone blocks receptors for morphine
Affinity
Tenancity with which a drug binds to a receptor
Routes of elimination
Hair Saliva Milk Sweat Skin Alveolar Bilary- ? Renal Faecal
Majority of drugs are excreted unchanged or as metabolites in urine or bile
e.g. alchol detected via breath
Potency
Amount of drug required to produce an effect of given intensity
‘First Pass’ Metabolism?
Relates to the liver
Most substances that are absorbed throughy GI tract are taken to portal system- includes drugs
The subs are taken to liver for processing, stoarge or metabolised
Some drugs metabolised so well that cannot be given orally - GTN (96% destroyed in liver)
LEARN MORE
96% of this drug is destroyed in liver
GTN
broncho…?
Blood Brain Barrier
400 miles of capillaries and veins safeguarded
epithelial cells between capillaries and brain - very tightly packed, creating a barrier
blocks movement of certain substances e.g. urea, creatinine
Cerebral capillaries - how different from body capillaries?
Endithelial cells are close together creating barrier
Can’t pass - urea, creatinine, red cells, white cells, protein
Can - oxygen, glucose, alcohol, nicotine, lipid soluble
amino acids
What opens up BBB?
trauma infection microwaves radiation hypertension
Other bodily barriers?
Placental - most drugs cross this
Testicular - little understood
Drug Half Life
Time taken for concentration to decrease by half
Morphine has short half life
Adrenaline has very very smol half life -
Bioavailability
The proportion of the drug which reaches the circulation
IV drugs - Bioavailability of 100%
Swallowed? - only a proportion
Has to pass through GI system, liver, before reaches circulatory system
Bioavailability
The proportion of the drug which reaches the circulation
IV drugs - Bioavailability of 100%
Swallowed? - only a proportion
Has to pass through GI system, liver, before reaches circulatory system
Steady State
Maintain a consistent concentration of a drug
Half life of 48 hours - 2 weeks to take a steady state
Half life of 2 hours - less than a day
‘Loading dose’ often used to achieve a steady state
For all drugs there is a minimum effective concentration and maximum safe concentration
e.g. taking antibiotics consistently to allow steady state
Therapeutic Index
Ratio of a drug that produced toxicity to a dose that provides a clinically desired or effective response
Large index - wide margin to reach toxic levels e.g. penecillin
Small index - toxic levels reached very quickly e.g. warfarin
Individual patient variation more likely in drugs with a smaller index as effective and toxic plasma concentrations are similar
Measuring drug levels frequently - why?
e.g.?
Likely to have a small therapeutic index
e.g. lithium, warfarin
How do drugs work?
RECEPTOR THEORY - receptors that determine and detect presence of specific drugs and initiate or inhibit an action. This can be blocked by another drug or chemical
ANTIMETABOLITES - closely resemble substances required for cell metabolism and nutrition
ENZYME INHIBITOR - drugs interfere with action of body enzymes therefore preventing certain chemical processes and reactions from occuring
ACTION ON CELL MEMBRANES - interfere with chemical activity of cell membrane and function
REPLACEMENT OF DEFICIENCIES - here drugs replace a dietary factor or hormone essential for normal fucntion
CYTOTOXIC EFFECTS - used to kill bacteria or malignant cells without undue harm to other cells. Interference with cell activity may occur and multiplication stopped - antibiotics
How do drugs work?
RECEPTOR THEORY - receptors that determine and detect presence of specific drugs and initiate or inhibit an action. This can be blocked by another drug or chemical
ANTIMETABOLITES - closely resemble substances required for cell metabolism and nutrition
ENZYME INHIBITOR - drugs interfere with action of body enzymes therefore preventing certain chemical processes and reactions from occuring
ACTION ON CELL MEMBRANES - interfere with chemical activity of cell membrane and function
REPLACEMENT OF DEFICIENCIES - here drugs replace a dietary factor or hormone essential for normal fucntion
CYTOTOXIC EFFECTS - used to kill bacteria or malignant cells without undue harm to other cells. Interference with cell activity may occur and multiplication stopped - antibiotics
Total Body Clearance
Combo of liver and kidney action
Liver assists clearing by metabolising and or excreting drugs through bile. Drugs can therefore be excreted in faeces or reabsorhed within the liver to be excreted via the kidney.
In certain instances, lungs are the main organs for elimination
Patients with kidney or liver problems?
Often take lower doses as the drugs remain in the system for longer than normal.
Total Body Clearance
Combo of liver and kidney action
Liver assists clearing by metabolising and or excreting drugs through bile. Drugs can therefore be excreted in faeces or reabsorbed within the liver to be excreted via the kidney.
In certain instances, lungs are the main organs for elimination
