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week 11 (Y2) > the medicine > Flashcards

the medicine Flashcards

1
Q

what is pharmacokinetics

A

processes that affect the drugs stay in the body

Study of what the body does to the drug.
Examines processes of absorption, distribution, metabolism, and excretion.
Influences drug concentration in the body over time, aiding in dosage determination.

studys how the body processes the drug

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2
Q

what is pharmacodynamics

A

drug or target / drug interactions

Study of the effects of drugs on the body and their mechanisms of action.
Explores interactions with target receptors and molecular components.
Focuses on dose-response relationship, potency, and efficacy of drugs.

looks at drugs effects on the body

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3
Q

describe the process of physiology and mission control

A

cellular/tissue/organ housekeeping/maintenance

instruction outflow: neuronal/peptides and small molecules

activators: release of factors
increased neuronal output
increased protein synthesis

activator effects feedback to mission control indirectly via sensors

biosensors: pressure
neuronal activity
change in peptides
small molecules
ions

data flow:
neuronal/ peptides/ small molecules

site: organelles, cells, tissues, organs

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4
Q

mission control overview

A

mission
instruction outflow (neuronal)
activators
effects feedback
biosensors
data inflow
site (organelles / cells)

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5
Q

medulla oblongata overview
pathology BP control

A

mission: BP control

hypertension: command to increase BP

instruction outflow: neuronal / peptides

activators: vascular resistance / heart rate and force

activator effects feedback to mission co tell i directly via sensors

sensors: peripheral vascular resistance / central medulla pressure receptors

hypertension: se sores read pressure as too low

data inflow: largely neuronal

back to medulla oblongata

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6
Q

what is physiology

A

Physiology is the study of animal (including human) function and can be investigated at the level of cells, tissues, organ systems and the whole body. The underlying goal is to explain the fundamental mechanisms that operate in a living organism and how they interact.

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7
Q

what is pathology

A

the science of the causes and effects of diseases, especially the branch of medicine that deals with the laboratory examination of samples of body tissue for diagnostic or forensic purposes.

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8
Q

treated pathology (medulla oblongata example)

A

drug to lower BP

sensors detect drug effect

this is reported to the medulla

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9
Q

what do we demand from drugs

A

hit the target and nothing else

the drug must be selective

drug must have specificity

drug must have efficacy
(affinity and potency)

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10
Q

what does specificity mean

A

the quality of belonging or relating uniquely to a particular subject

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11
Q

what does efficacy mean

A

the ability to produce a desired or intended result

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12
Q

what does affinity mean

A

.
BIOCHEMISTRY
the degree to which a substance tends to combine with another

attraction between drug and receptor of enzyme

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13
Q

what does potency mean

A

Potency is an expression of the activity of a drug in terms of the concentration or amount of the drug required to produce a defined effect,

wether the interaction operates the receptor system

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14
Q

what is affinity plus potency

A

agonist

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15
Q

what is affinity plus no potency

A

antagonist

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16
Q

what do agonists do

A

mimic endogenous agents

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17
Q

what do antagonists do

A

drug blocks endogenous agent

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18
Q

what are anticander drugs

A

cytotoxic

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19
Q

what are streptokinase drugs

A

enzymatic

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20
Q

what are antacids

A

neutralizing agents

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21
Q

what are chelators in metal poisoning

A

binding agents

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22
Q

what are antibiotics

A

they kill invadors

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23
Q

what happens when an antagonist / agonist is activated

A

transporter molecule

function of receptor/protein channel/transporter has changed

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24
Q

how do agonists work

A

endogenous agent stimulates a substrate of a receptor / enzyme

the effect is proportional to the conc of the agent

drug conc is proportional to its pharmacological effect based on a certain affinity and maximal response

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25
Q

what happens with a partial agonist

A

burning or ligand response is less than 100% / response of full agonist

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26
Q

how do antagonists work

A

endogenous agent stimulates substrate of receptor or enzyme

effect is proportional to conc of the agent

blocks the endogenous agent or drug agonist and prevents the endogenous effect

antagonist has a similar affinity for the receptor / enzyme. it has no potency so prevents the function

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27
Q

what is competitive

A

agonist / antagonist have similar affinities

bind to the receptor / enzyme active site

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28
Q

what is non competitive

A

antagonist binds at a different site and prevents function

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29
Q

what is uncompetativity

A

inhibitor binds to receptor / enzyme / agonist complex

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30
Q

what is irreversibility

A

drug destroys enzyme or receptor

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31
Q

what is the law of mass action

A

when the agonist overcomes the inhibitor effect

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32
Q

when do you need enough agonist

A

lower affinity can still reach max potency by adding more agonist

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33
Q

what can non competitive inhibition overcome

A

the law of mass action

binds to allosteric site

antagonist cuts back max potency

34
Q

what type of interaction is uncompetitive inhibition

A

three way

not a common interaction

substrate binds to active site
inhibitor is on top of the substrate

no example of this

35
Q

what is quasi irreversible binding

A

binding of metabolic intermediate complex
MIC

active site metabolite mediates destruction

36
Q

when do you have to make a new enzyme

A

irreversible antagonists

37
Q

how to calculate the therapeutic index

A

TI = toxic concentrations / normal therapeutic range

changes in a narrow TI are more serious

38
Q

what % of hospital admissions can be drug adverse effect related

A

15%

half of these admissions are drug interaction related

39
Q

drugs that cancel each others effects

A

acwtylcholinesterases amd neuromuscular blockers

40
Q

binding to different systems but achieving the same effect drug examples

A

benzodiazepines and propofol

41
Q

same site competition drugs examples

A

benzodiazepines and barbiturates

42
Q

drug interactions
serotonin syndrome symptoms

A

agitation
restlessness
confusion
rapid and high heart rate
BP
dilated pupils
loss of muscle co ordination
twitching muscles
muscle rigidity
heavy sweating
diarrhea
headache
shivering
fever
seizures
death

43
Q

what is the key reasons for pharmacokinetic changes

A

hepatic metabolic changes
accumulation - drug toxicity - hours
disappearance - drug failure - days

44
Q

how can drugs be limited in their effectiveness

A

pharmacokinetics
pharmacodynamics
biological systems are dynamic, aware, and resistant

45
Q

what is the difference between specificity and selectivity

A

In summary, while specific drugs target a particular receptor or pathway with high affinity, selective drugs exhibit a preference for their intended target while minimizing interactions with other similar targets. Specificity refers to the precision of drug-target interactions, while selectivity relates to the degree of preference for a particular target over others.

selective - preferance for a receptor / target

specific - higher affinity

46
Q

describe non competative inhibition

A

Non-competitively-antagonist binds at a different site*, prevents function.

47
Q

example of non competative inhibition

A

miraviroc (anti-HIV)

allosteric effect

48
Q

what is preformulation

A

Preformulation is a branch of pharmaceutical sciences that utilizes biopharmaceutical principles in the determination of physicochemical properties of a drug substance

involves the preliminary investigation of a drug’s physical and chemical properties before formulation into a dosage form.

49
Q

goals of preformulation

A

to choose the correct form of drug substance
evaluate its physical properties
generate a thorough understanding of the material’s stability under various conditions, leading to the formulation of optimal drug delivery system

50
Q

why is preformulation so important

A

First learning phase in dosage form development
Fundamental physical and chemical properties are ascertained
Only small quantity of drug substance available (mg)

51
Q

what two things can you caracterise from preformulation

A

drug characterisation
analytical charactisation

52
Q

pharmaceutical profiling of drug charactarisation, how do you do it
give examples of methods used

A

Assay - UV, HPLC, TLC
Solubility (aqueous, pKa, salts, solvents, partition co efficient, dissolution)
Melting point
Stability
Microscopy
Powder flow (bulk density, angle of repose)
Compression properties
Excipient compatibility

53
Q

Analytical preformulation
give examples of methods used

A

Identity
- NMR, IR, UV, DSC, TLC
Purity
- Moisture content, inorganic and organic
impurities, DSC
Assay
- UV, HPLC
Quality
- Appearance, odour, colour, melting point

All the above used to confirm structure and purity

54
Q

when do compounds tend to have bioavailibility issues

A

Compounds with solubility less than 1% (pH 1-7 at 37⁰C) potentially have bioavailability issues

55
Q

what are the poential solutions for drugs that may have possible solubility issues

A

Solubility in the range of 1-10mg/ml – salt formation desirable (only possible for ionisable drugs)
Alternatively, liquid filling in capsules eg: neutral molecules, steroids etc

56
Q

what is the definition of intrinsic solubility (Co)

A

– the fundamental solubility in an unionised state

57
Q

why is solubility measured at two tempratures

A

Solubility measured at two temperatures – 4⁰C (to support physical stability and short term storage) and 37⁰C (for biopharmaceutical evaluation)

58
Q

what does solubility data shed light on?

A

Solubility data sheds light on pKa and formulation approaches

59
Q

tell me about pKa, and what is it?

A

75% of all drugs are basic
20% are weak acids
5% non ionic

pKa stands for the acid dissociation constant, which is a measure of the strength of an acid in a solution. Specifically, it represents the equilibrium constant for the dissociation reaction of an acid in water.

60
Q

why is pKa useful

A

Used to maintain solubility by altering pH of solution
Formation of appropriate salts for the poorly soluble parent drug

61
Q

tell me abot salt formation, adv and dis

A

Salts of strong acids/bases are freely soluble but suffer from high hygroscopicity leading to instability in tablet/capsule formulation

Weaker acids/bases used to form salts (eg: maleate, acetate, aluminium)

62
Q

what is intrinsic pH

A

“Intrinsic pH” typically refers to the inherent pH of a solution or medium without the addition of any external acidic or basic substances. It is determined by the concentration of hydrogen ions (H+) in the solution, which in turn affects its acidity or basicity.

63
Q

what are the impacts of salt formation

A

Lowers intrinsic pH thereby increasing solubility exponentially

Dissolution rate of salt higher than parent drug

However, alterations in solubility/dissolution may affect bioavailability

64
Q

what is QbD

A

QbD stands for Quality by Design, a systematic approach to pharmaceutical development that emphasizes the understanding of product and process variability and the application of scientific principles to ensure product quality. In essence, QbD shifts the focus from merely testing the final product to designing quality into the product from the outset of the development process.

65
Q

Preformulation characteristics of Temazolamide?

A

Temazolamide is a medication used primarily in the treatment of certain types of brain tumors, such as glioblastoma multiforme. Before formulating Temazolamide into a dosage form, various preformulation studies would be conducted to understand its physical and chemical characteristics. Here are some preformulation characteristics of Temazolamide:

solubiity
stability
particle size
pKa

66
Q

tell me about solvents and the most commonly used one

A

Water is the commonly employed solvent
However aqueous instability is sometimes an issue (eg: chlordiazepoxide HCl is hydrolysed)
Water miscible solvents used instead
To improve solubility/ stability eg; glycerol, propylene glycol
In analysis for extraction and separation eg: methanol, ethanol

67
Q

what is the partition coefficient

A

Kw

Def: the solvent : water quotient of drug distribution
Uses:
- gives information on aqueous and mixed solvent solubility
- drug absorption in vivo
- choice of column (HPLC) or plate (TLC)

68
Q

what is the equation for Kw

A

K⁰w = (∑C-Cw)/(Cw)
C = concentration in aqueous phase before partitioning
Cw = concentration after partitioning

69
Q

what partition is the most commonly employed

A

Octanol/ water partition most commonly employed
Method : Shake flask method
- drug assayed in aqueous phase of the mixture

70
Q

tell me about dissolution

A

Dissolution rate of drug is important where it is the rate limiting step in absorption
When dissolution controlled solely by diffusion, rate proportional to the saturated concentration of the drug in solution

71
Q

what are the two types of dissolution and the differneces between them

A

Dissolution rate of drug is important where it is the rate limiting step in absorption
When dissolution controlled solely by diffusion, rate proportional to the saturated concentration of the drug in solution

In summary, intrinsic dissolution measures the rate of dissolution of pure drug substance under controlled conditions, providing insights into its inherent dissolution properties. Total dissolution, on the other hand, assesses the complete release of the drug from a dosage form, helping to evaluate its performance and bioavailability in practical applications. Both intrinsic dissolution and total dissolution testing are important tools in drug development and quality control.

72
Q

what are the units for intrinsic dissolution

A

mg cm^2 / min^-1

73
Q

what are the units for total dissolution

A

mg/ml

74
Q

what is IDR

A

intrinsic dissolution rate

It refers to the rate at which pure drug substance dissolves under standardized conditions, typically measured in micrograms per minute or milligrams per square centimeter per minute.

Independent of formulation effects and measures intrinsic properties of drug

75
Q

IDR equation

A

IDR = K1 X Cs

IDR = rate constant X solubility or concentration in sink conditions

76
Q

what is total dissolution, and what cannot be controlled

A

exposed surface area cannot be controlled as disintegration, disaggregation and dissolution proceed

77
Q

what is the equation for total dissolution

A

Dc/Dt = A/V X K1 X Cs

surface area / volume X rate constant X solubility or concentration in sink conditions

78
Q

what is the common ion effect

A

Common ion significantly reduces the solubility of a slightly soluble electrolyte
Two types
Salting out: due to removal of water molecules as solvents i.e. hydration of other ions
Salting in: due to larger anions which open the structure of water eg: benzoates, salicylates

79
Q

what is salting in

A

Salting in: due to larger anions which open the structure of water eg: benzoates, salicylates

Salting out: due to removal of water molecules as solvents i.e. hydration of other ions

80
Q

what is salting out

A

Salting out: due to removal of water molecules as solvents i.e. hydration of other ions

Salting out occurs when the addition of a common ion to a solution decreases the solubility of a slightly soluble salt.

81
Q

how can melting point be measured

A

Can be measured using three different techniques
Capillary melting- to determine melting range
Hot stage microscopy – consists of heated sample stage
Differential scanning calorimetry (DSC)
Uses
Melting point determination and phase changes shed light on polymorphism
Also used for excipient selection

82
Q
A

week 11 (Y2) (3 decks)

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