Pharmacology

Question 1

who regulates the use of medicines in the uk

Answer 1

the medicines air and human medicines regulations 2012 regulate the use of medicines In the uk

before any meeiidicne can bee supplied it is required to have marketing authorisation granted by thee medicines and healthcare products regulatory authority

Question 2

what is the legality we need for prescription only medicines

Answer 2

has to be prescribed – in order to use the medicine you need a prescriber to supply the medicine ,

Question 3

what are prescription only medicines

Answer 3

can only be obtained with a prescription

Question 4

what is pharmacy medicine

Answer 4

can only be purchased under the supervision of a pharmacist in registered premises

Question 5

what is general sales list medicines

Answer 5

can be sold in general shops without supervision

Question 6

why can we allow access to medicines without a prescription

Answer 6

If anyone buys gsl and someone dosnt follow instructions the harm they can cause is limited

Question 7

what legal category does paracetamol 500mg x 32 fall under

Answer 7

legal category is pharmacy only

Question 8

what legal category does paracetamol caplets 500mg fall under

Answer 8

this is a pom

prescription only medicine - has to be prescribed

Question 9

what legal category do small packs of paracetamol fall under

Answer 9

small packs (16) of paracetamol are general sales list

Question 10

what are p and gsl medicines referred to

Answer 10

often the p and GSL medcines are described as ‘‘over the counter’’ medicines

the term oct has no legal meaning

Question 11

what is the legislation behind ahps being able to prescribe drugs

Answer 11

The Crown Reviews (1998/99) - recommendations about the use of medication without a prescription (Medicines Act exemptions and Non-Medical (independent) prescribing)

“Legal authority for new professional groups to prescribe or to authorise NHS expenditure ..limited to medicines in specific therapeutic areas related to the particular competence and expertise of the group and may include prescription only medicines within those areas.”

Legislation amended to enable adequately trained HCPs to become Ips- independent prescribers- and some to exemptions to supply and administer POMs (Eg. Paramedics, midwives and most recently, podietrists & orthoptists).

Question 12

what is pharmacokinetics

Answer 12

the movement of drugs into and out of the body

'’what the body does to the drug’’

Question 13

what is pharmacodynamics

Answer 13

how drugs work when they reach their site of action

'’what the drug does the body’’

Question 14

what is first pass metabolism

Answer 14

First pass metabolism is the process in which a drug is partially metabolized or broken down by the liver before it enters the bloodstream and reaches the rest of the body. Essentially, when you take a medication by mouth, it travels to the liver first, where some of it may be changed into different forms before circulating throughout the body. This can affect the effectiveness and concentration of the drug that actually reaches the target tissues or organs.

Question 15

describe the pharmokinetic process

Answer 15

starts with administration of the drug this can be extravacualrly or intravscualry e.g. swallowing pills or injections (intravascular administration)

it then gets absorbed into the gut wall and then the blood and then it gets distributed to the body tissus and then it gets metabolised by the liver and eliminated by the kidney

Question 16

what type of metabolism does extravascular administration of drugs elicit

Answer 16

first pass metabolism

First-pass metabolism, also known as the first-pass effect, is a phenomenon that occurs when drugs or other substances are taken orally (by mouth) and pass through the liver before entering the systemic circulation (the bloodstream). This process can significantly affect the bioavailability and effectiveness of the drug.

Not all drugs are subject to significant first-pass metabolism. Some drugs are designed to be resistant to this process, while others are intentionally administered orally because first-pass metabolism can lead to the formation of active metabolites.

Question 17

how are people are long term drugs managed to ensure there kidney and liver function isn’t affected

Answer 17

Blood tests done once a year to check liver and kidney functions
Blood level against time when durg is put into body
Liver – LFT, KIDNEYS – U and E

(urea and electrolytes)

Question 18

where are the following routes of administration absorbed in the body:

sublingual

buccal

intraocular

respiratory tract

Answer 18

sublingual
under tongue

buccal
oral mucosa

intraocular
eyes

rectal
lower GIT

respiratory tract
nasal passages or lungs

Question 19

where are the following routes of administration absorbed in the body;

intravenous

intramuscular

subcutaneous

intracathcal

intravitrial

Answer 19

intravenous
directly into venous blood

intramuscular
muscles

subcutaneous
into blood from skin layers

epidural
epidural space

intracathecal
directly into cerebrospinal-spinal fluid

intravitrial
into vitreous space near retina

Question 20

what are the advantages of taking medication orally

Answer 20

Advantages
Convenient
Self administration
Simple
Economical
Liquids often available
“first pass metabolism”- formulate drug to undergo first pass metabolism and produce a metabolite

Question 21

what are the disadvantages of taking medication orally

Answer 21

Not all drugs active orally e.g. insulin
Unpredictable absorption- some loss as the drug crosses lipids in the body
Delayed onset of action
Gastrointestinal side effects
“first pass metabolism”

Question 22

what are the advantages of taking medication intraveously

Answer 22

Advantages
Immediate
Predictable effect
Large volumes
Infusion allows maintenance of effect
Avoids ‘1st pass’ metabolism

Not extravscuallry going straight into blodtsrem therefore immeadite relase in blood stream ni lipid lyers for durg to be broken down at

Question 23

what are the disadvantages of taking medication intravenously

Answer 23

Risky
Infection
Phlebitis
Preparation time
Anaphylaxis
Infusion calculations
Expensive
Staff involvement
Incompatibilities

Question 24

what are topical drug examples

Answer 24

Topical drug therapy ‘Apply to affected area’

Creams
Ointments
Nasal sprays
Eye drops / ointment
Ear drops
Inhalers
[Nasal sprays]
[Eye drops / ointment]
[Transdermal Patches (Buprenorphine, fentanyl, hyoscine, HRT)]

transdemeral patches are not topical drugs

Question 25

what are the advantages of topical drug therapy

Answer 25

ADVANTAGES
↓ systemic side effects-
Useful if swallowing difficulties
Onset of action may be quicker
Compliance

Question 26

what are the disadvantages of topical drug therapy

Answer 26

Compliance?
Physical difficulties?
Reactions at site
Staining of clothing
Delayed onset of action-relys on skin intergrity e.g. hydrated
Misconception that topical = safe

Question 27

what does the pharmokinetic paramete ‘‘half life’’ refer to

Answer 27

Half life is the time required to reduce the (drug) plasma concentration to half of its original value

Also refered to as t ½
Can vary from drug to drug and from person to person
Does not depend on dose / dose frequency
Use to calculate dosage frequency / time to ‘steady state’

Question 28

what does the pharmokinetic parameter bioavailabliity refer to

Answer 28

Bioavailability is the fraction of the administered dose that reaches the systemic circulation of the patient- fraction of the drug we give that reaches systemic circulation – e.g. by iv injection = 100 percent
Affected by:
Dosage form
Dissolution and absorption of drug
Route of administration
Stability of the drug in the GI tract (if oral route)
Extent of drug metabolism before reaching systemic circulation
Presence of food/drugs in GI tract

Question 29

what is half life

Answer 29

Half-life is the time taken for the concentration of the drug in the blood to fall by half

Question 30

how is the frequency of drug dosing affected by half life (e..g. short life drugs)

Answer 30

Generally a drug with a short half-life is given more frequently
E.g. paracetamol t ½ = 2 – 4 hours
Usual dose? -
1g every 4 to 6 hours to maintain effective pharmcodynamic effect from paracetamol;

Question 31

how is the frequency of drug dosing affected by half life (e.g. long half life drugs)

Answer 31

Generally a drug with a long half-life is given less frequently
E.g. warfarin t ½ = 24 hours
Usual frequency? -
Given once daily

Question 32

what is the significance of bioavailablity

Answer 32

How do we need tp change doses if we are going from iv route to oral route

Bioavailability when changing from IV to oral route of administration
e..g propanol iv 100%

oral 30 to 40%

\

Question 33

what are the four processes of the pharmokinetic process

Answer 33

4 process
Absorptiion
Dstribution
Metabolism
Eliminarion

Question 34

describe the adsorption part of pharmokinetics

Answer 34

Most medicines are given orally and they must pass through the semi-permeable (lipid) membrane of the gut before reaching the systemic circulation (blood stream). – risk of loss of molecules – what yo put in ihg tnot be available for pharmacodynamic reaction

Absorption can be affected by many factors – including the route in which the medicine is given but is generally proportional to the lipid solubility of the medicine. – main barrier to absorption = has pt used meds and have they used it in the right way

Therefore, the absorption of non-ionised molecules is favoured as these are far more lipid soluble.

A medicine given by intravenous injection is put straight in to the blood stream and is therefore rapidly distributed to tissues

Question 35

what are barriers to absorption

Answer 35

Concordance *******
Food / Drink
Formulation
Blood flow- e.g. diabetes
Route of administration
Lack of specific receptor needed for absorption
Gastric emptying- drug on empty stomach – drug is dormant
GI motility
Inactivation of drug in gut or liver
Pre-existing medical conditions
Drug interactions

Question 36

describe the distribution part of pharmokinetics

Answer 36

required to distribute the medicine to body tissues

Process where drug moves away from site of absorption to other areas of the body

Each drug is uniquely distributed in the body, some go into the fat (lipid) and others remain in the extracellular fluid

Drugs are found remotely from the desired site of action which can account for some side effects

Major barriers to distribution: Cell membranes
Capillaries
Blood Brain Barrier- thick lipid barrier

Question 37

what are the barriers to distribution

Answer 37

Plasma protein binding Competition for protein binding sites (distribution may rely heavily on plasma protein binding)
NB Bound drug– inactive / free drug – active- protein acts as a drug carrier – makes the drug inactive because using energy to adhere to protein when it reaches site of action drug is active – if drug becomes dsrbuted wrongly can become active in wrong places

Regional blood flow - Reduced blood flow e.g. Diabetics

Lipid solubility - Blood/brain barrier – generally if increased lipid solubility then increased penetration

Disease - Liver disease can cause low plasma protein levels. Renal disease causes high blood urea levels

Question 38

describe the metabolism part of pharmokinetics

Answer 38

The liver is the main site of drug metabolism. However, the gastrointestinal system and the lungs have considerable metabolic activity.
The primary aim of drug metabolism is to render a molecule as water soluble as possible so that it can be eliminated from the body by the kidneys.
Metabolites tend to be less active than the parent compound although some, termed ‘active metabolites’ may be more potent if the parent compound was administered as a ‘pro-drug’ (an inactive compound on administration which is activated by metabolism).

Question 39

what is first pass metabolism

Answer 39

Compounds given orally are primarily absorbed in the small intestine and enter the portal system which takes the drug molecule to the liver before effective distribution to body tissues.
If the result of this first pass metabolism is an ineffective compound, then the medicines is not therapeutically viable by the oral route

Question 40

what factors affect metabolism

Answer 40

Genetic factors
e.g acetylation status – breakdown meachanism in liver = acetylation (‘fast- break down meds to quick /slow- risk of accumalatig meds metaboliser’)

Age
Impaired or immature hepatic enzyme activity
Elderly- may metabolise less effectively
Children < 6 months (especially premature babies)

Other drugs
hepatic enzyme inducers- quickens metabolism in liver
hepatic enzyme inhibitors- slows down metabolism could result in accumulation of medication

Question 40

describe the process of elimination/ excretion

Answer 40

Many compounds are primarily excreted by the kidneys.
Water soluble compounds appearing in the glomerular filtrate will be eliminated in urine whereas lipid soluble compounds will be reabsorbed by passive diffusion in to the renal tubules.
Some compounds are concentrated in bile and excreted in to the intestine where they may be re-absorbed (enterohepatic re-circulation-can increase the persistence of the drug in the body) or eliminated in faeces.
Other routes of elimination include sweat, tears, genital secretions and breast milk

Question 41

how is kidney function and age correlated

Answer 41

Kidney function declines with age – drop In filtration rate in the kidneys

Question 41

deine pharmacodynamics

Answer 41

How drugs work when they reach their site of action

Question 42

what are the actions of drugs

Answer 42

Drugs may act on:

One of the components of the cell
One of the critical chemical pathways of the cell
Transport mechanisms allowing chemicals into and outside of cells
Chemical messaging systems between cells
DNA / RNA replication

Question 43

how to drugs interact with animal cells

Answer 43

drugs can damage cell walls

Question 44

how to drugs act on cell walls

Answer 44

Some antibiotics damage the bacterial cell wall
Cell becomes leaky and dies and therefore as bavteria usually proliferate to creates infection stops bacteria from proliferating
Example: penicillin

Question 45

how to cells transport molecules though cell walls

Answer 45

Cells need to transport molecules into and out of the cell
Some molecules can pass through according to:

Size Smaller the better

Electric charge Less highly charged the better
Polarity

Question 46

how to cells ensure a molecule gets through a cell

Answer 46

By giving the molecule polartity it forces the molecule through the cell membrane even though it is to big

Question 47

what is osmosis

Answer 47

Osmosis is the passage of solvent such as water through a semi-permeable membrane from a less concentrated solution into a more concentrated one

ie.spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides).