Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MP422 > CNS DRUG FORMULATIONS > Flashcards

CNS DRUG FORMULATIONS Flashcards

1
Q

requirements to cross the BBB

A

lipid-soluble
MW <400 Da

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

why can/t dopamine pass the BBB

A

hydrophilic
too polar
low lipid solubility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

why can the dopamine precursor levodopa pass the BBB but not dopamine

A

levodopa is hydrophobic but can cross the BBB by carrier-mediated transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how do anti-epileptics cross the BBB

A

diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

dosing for AEDs

A

long enough half-life to allow once daily dosing (except sodium valproate, carbamazepine and gabapentin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

advantages of conventional tablets

A
  • accurate dosing of the drug
  • convenient to handle
  • easy to take
  • controlled release of the drug
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

disadvantages of conventional tablets

A
  • poor bioavailability of some drugs
  • local irritants effects
  • harm caused to the GI mucosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

enteric coats for GR tablets

A

polyvinyl acetate phthalate
diethyl phthalate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

gastro-resistant tablet design properties

A
  • barrier coating to control the site of the release of the drug
  • designed to resist the low pH of gastric fluids (1.5-4) but to dissolve when the tablet reaches the higher pH of the duodenum (from 5)
  • should be swallowed whole
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

advantages of gastro-resistant tablets

A
  • delay the release of the drug until it reaches the small intestine
  • protect the drugs that would be degraded by gastric fluid
  • protect the stomach against drugs that can produce nausea or mucosal irritation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

orodispersible tablet properties

A
  • disintegration of the tablet in the mouth within one min in the presence of saliva
  • can be dispersed in a liquid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

advantages of orodispersible tablets

A
  • no difficulty swallowing
  • more accurate dosage of drug to young children
  • fast effect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

example of gastro resistant tablets

A

sodium valproate (epilim)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

examples of orodispersible tablets

A

co-beneldopa (PD)
lamotrigine (epilepsy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

chewable tablet properties

A
  • tablets mechanically disintegrated in mouth
  • drug dissolved in the stomach or intestine
  • no need of a disintegrant (composition)
  • need of flavouring: use of sorbitol and mannitol as fillers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

advantages of chewable tablets

A
  • quick and complete disintegration of the tablet
  • rapid drug effect
  • easy administration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

examples of chewable tablets

A

carbamazepine (tegretol chewtabs)
phenytoin (epilepsy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

matrix system types in modified-release tablets

A

erosion-controlled matrix systems
diffusion-controlled matrix systems
diffusion-and-erosion controlled matrix systems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

erosion-controlled matrix systems

A
  • the rate of drug release is controlled by the erosion of a matrix in which the drug is dispersed
  • eroding matrix: lipids, waxes, polymers (hydroxyethylcellulose)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

example of erosion-controlled matrix system MR tablets

A

carbidopa + levodopa (sinemet)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

diffusion-controlled matrix system

A
  • drug dispersed as solid particles within a porous matrix formed of a water-soluble polymer (polyvinyl chloride)
  • dissolution of drug particles located close to the surface
  • diffusion of the drug through pores
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

example of diffusion-controlled matrix system MR tablets

A

ropinirole (ReQuip XL)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

three-layered tablet

A
  • a central, active-containing, slow-release layer
  • 2 placebo outer layers acting as barrier layers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

diffusion and erosion-controlled matrix systems

A
  • penetration of GI fluids in the matrix
  • dissolution of the drug, diffusion
  • erosion: separation of the matrix surface from the core > release of the drug
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

examples of diffusion and erosion-controlled matrix systems MR tablets

A

pramipexole ER
sodium valproate (epilim chrono)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

extended release tablets

A
  • tri-layer capsule-shaped rigid tablet
  • use of the osmotic release oral system (OROS) technology
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

osmosis

A

spontaneous flow of solvent through a selectively permeable membrane from a compartment with a low solute concentration to a compartment with a high solute concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

disadvantages of modified-release capsules

A
  • no opening of the capsules
  • not suitable for patients with swallowing difficulties
  • unsuitable for administration via enteral feeding tubes
29
Q

advantages of granules

A
  • ensures more even plasma concentration throughout the day
  • easy to swallow
30
Q

disadvantages of granules

A
  • must not be administered with hot meals or drinks (damage to the ethyl cellulose shell granule coat)
  • should not be crushed or chewed
31
Q

when is an oromucosal solution the most suitable

A
  • prefilled oral syringe containing midazolam solution, pH 2.9 to 3.7
  • treatment of prolonged acute convulsive seizures in infants, toddlers, children and adolescents (3 months to <18)
  • slow insertion of the solution into the space between the gum and cheek
  • fast absorption of the drug in the circulation
32
Q

transdermal administration CNS drug requirements

A
  • have a low molecular weight (<500Da)
  • have an aqueous solubility higher than 1mg/ml to be removed by the blood supply
  • be moderately lipophilic (log P between 1 and 5)
  • be effective at low dose
  • have a low melting point
33
Q

what do transdermal drugs need a low melting point

A

MP <250 degrees
the lower the melting point of the drug, the higher its solubility in the stratum corneum lipids

34
Q

matrix-type transdermal patch (Neupro for PD)

A

ex. rotigotine (Neupro)
- application of the patch once a day at the same time
- patch remains on the skin for 24 hours
- it will be replaced by a new one at a different site

35
Q

advantages of matrix-type transdermal patch (Neupro for PD)

A
  • slow release and long lasting > indicated for the treatment of the signs and symptoms of early stage PD as monotherapy
  • avoidance of hepatic first pass metabolism
  • can be removed quickly and easily in case of adverse reactions
  • application to various body parts
36
Q

disadvantages of all matrix-type transdermal patches

A
  • no exposure to external heat source: risk of increasing the rate and extent of drug absorption: overdose
  • no exposure to water (adherence)
  • the backing layer of Neupro contains aluminium > removal of the patch if the pt undergoes MRI or cardio version to avoid skin burns
  • contact sensitisation: erythema
37
Q

rectal administration formulation and drug example

A

suppositories
intestinal gel

Ex: co-beneldopa (duodopa): gel that is pumped continuously through a tube inserted into the intestine (jejunum)

absorption of the drug in the blood

38
Q

advantages of duodopa

A
  • suitable for patients who have no control of PD symptoms with traditional treatments
  • continuous release
  • less likely involuntary movements, fewer ‘off’ periods, help to control PD symptoms at night
  • avoid problems of gastric emptying
39
Q

advantages of solutions for injections/infusions

A
  • dependable and reproducible effects
  • entire administered dose reaches the systemic circulation immediately
  • preferred route when rapid absorption is essential
40
Q

disadvantages of solutions for injections/infusions

A
  • pain at the injection site
  • all parenteral products must be sterile
  • IV injection of drugs may cause local reactions
41
Q

preferred formulations in neurosis

A

oral/transdermal

42
Q

preferred formulations in psychosis

A

IV/IM

43
Q

compliance with benzodiazepines

A
  • dependence may occur after 4-6 weeks of treatment
  • decrease dose by 1/8th every fortnight
  • withdrawal can take months
44
Q

compliance with antidepressants SSRIs

A
  • use of full dose for 4-6 months after symptoms have subsided is essential to prevent relapse
  • non-compliance is frequent when the patient’s mood has improved
  • withdrawal over 2-4 weeks
45
Q

schizophrenia - issues with compliance and formulations

A

paranoid delusional state > pt not swallowing tablets

concentrated oral liquid forms help because they cannot be hidden in the mouth rather than swallowing

syrup-base preparations can cause tooth decay and obesity in long term > oral dispersible forms are preferred

  • minimum 5 year maintenance period recommended
  • compliance discouraged with weight gain, precipitates diabetes
46
Q

sublingual tablets

A
  • drug release in the mouth followed by systemic uptake of the drug
  • rapid systemic effect, without first pass liver metabolism
  • placed under the tongue

Ex: buprenorphine (addiction)

47
Q

extended release capsules containing 2 types of beads

A

beads without release control membrane (uncoated beads): 30% of dose rapidly released

beads with release control membrane (coated beads):
70% of dose continuously release

48
Q

advantages of suspensions

A
  • drug absorption faster than tablets or capsules
  • convenient when the drug is not soluble in water and when non-aqueous solvent cannot be used
  • the insoluble solids act as a reservoir and continuously release the drug > long-term efficacy
49
Q

disadvantages of suspensions

A
  • risk of sedimentation
  • risk of inaccurate dosage (use of a spoon)
50
Q

advantages of solutions/syrups

A
  • drug already dissolved > absorption faster than solid dosage forms or suspensions
  • masking the unpleasant taste of the drug
  • easy to adjust the dose for a child’s weight
51
Q

disadvantages of solutions/syrups

A
  • risk of deterioration faster than solid dosage forms
  • risks of inaccurate dosage (spoon)
52
Q

matrix-type transdermal patch (methylphenidate and buprenorphine)

A
  • application of the patch to the hip area 2 hours before an effect is needed
  • removal of the patch 9 hours after application
  • regular drug release for 9 hours
53
Q

injections

A

sterile solutions, emulsions or suspensions, in water or non-aqueous liquid

54
Q

depot therapy

A
  • injection of a drug with a substance that slows the release and prolongs the action of the drug
  • IM injection into skeletal muscle > slow release of the drug to the plasma
55
Q

chemistry behind depot therapy

A

esterification of the drug, dispersion of the drug in an oily vehicle

de-esterification of the drug by hydrolysis to be active

56
Q

duration of depot therapy

A

effective plasma therapeutic level reached within one week, maintained for 14 to 28 days > injection every 2 to 4 weeks

57
Q

advantages of depot therapy

A
  • lower dose compared to oral administration
  • regular contact with patient by carers
  • supervised administration
  • no accumulation or abuse of unused tablets
  • no issue of compliance
58
Q

disadvantages of depot therapy

A
  • pain at the injection site
  • no rapid elimination from the body
  • considerable patient resistance
59
Q

BBB crossing - donepezil hydrochloride

A

carrier mediated transport (organic cation transporter such as choline transport system)

60
Q

BBB crossing - rivastigmine

A

diffusion

61
Q

BBB crossing - galantamine

A

choline and carnitine transport systems

62
Q

BBB crossing - memantine

A

organic cation/carnitine transporter

63
Q

formulation/compliance issues with elderly patients

A
  • high numbers of drugs to take > risk of mistakes
  • difficulties to remove meds from their blisters/containers
  • may not remember to take their medication
  • difficulties swallowing (dysphagia)
64
Q

dose and side effects of conventional tablets of donepezil (Aricept)

A
  • coated tablets to facilitate swallowing
  • 5mg daily at bedtime
  • increased to 10mg after 1 month if no s/e

side effects: diarrhoea, muscle cramps, fatigue, nausea, vomiting and insomnia

65
Q

dose and side effects of conventional tablets of memantine (Ebixa)

A
  • 5mg once daily
  • increased weekly to max 20mg

side effects: dizziness, headache, constipation, somnolence and hypertension

66
Q

dispersible tablets of donepezil hydrochloride

A
  • taken at bedtime
  • should be placed on the tongue, allowed to disperse and swallow
  • disintegration of the tablet in the mouth within one minute in the presence of saliva
67
Q

advantages of dispersible tablets

A
  • suitable for patients who cannot swallow tablets or capsules
  • fast release of the drug
68
Q

3 layers in dispersible tablets

A

drug
fast dissolving granules
disintegration agent

69
Q

process of disintegration of dispersible tablets

A
  1. contact with saliva
  2. swelling of the disintegration agent
  3. creation of channels for the saliva
  4. penetration of saliva
  5. dissolution of fast dissolving granules
    - disintegration of the tablet

MP422 (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions