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53 > 9. Formulations > Flashcards

9. Formulations Flashcards

1
Q

where are the drugs absorbed in the nose

A

olfactory region (connected to CNS, highly vascularised, 15 cm2 surface area)

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2
Q

3 types of intranasal transport

A
  • Paracellular transport (passive)
  • Transcellular transport (active)
  • Intraneuronal transport (active)
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3
Q

describe paracellular transport

A

(passive): rapid uptake, passive transport through gaps between cells

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4
Q

how does high turnover of olfactory sensory neurons affect paracellular transport

A

high turnover of olfactory sensory neurons can leave more gaps → increase paracellular transport

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5
Q

describe transcellular transport

A

(active): slow process

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6
Q

describe intraneuronal transport

A

(active) - interact with surface of synapses

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7
Q

advantages of intranasal delivery (4)

A
  • non-invasive
  • self-administered
  • bypass hepatic first-pass effect
  • short onset of effect (short distance btw nose and brain)
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8
Q

barriers to intranasal delivery (7)

A
  • Nasal epithelial layer - drug need to penetrate the epithelial layer
  • Nasal mucus - trap the drug
  • Metabolic enzymes - can breakdown drug
  • Efflux pump - decrease drug absorption
  • Hair - trap drugs
  • Mucociliary CL - sweep drug out of nose
  • Volume - dilute the concentration of drug at site of absorption (olfactory region)
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9
Q

Characteristics of an ideal drug candidate for CNS drug delivery

A

Lipinski’s rule of 5
- ≤ 5 hydrogen bond donor
- ≤ 10 hydrogen bond acceptor
- < 500Da
- < 300Da for N2B access of hydrophilic drugs
- < 1kDa for N2B access of lipophilic drugs
- Log P < 5 (higher log P more lipophilic)
- Unionised

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10
Q

size of hydrophilic drug for N2B access

A

< 300Da

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11
Q

size of lipophilic drug for N2B access

A

< 1kDa

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12
Q

how can delivery systems help to deliver drug to CNS

A
  • make drug physically manageable - API too small in quantity (make into tablets/ liquids)
  • improve drug solubility
  • improve drug absorption/ permeation
  • protect drug from degradation (by macrophages) and excretion (decrease renal excretion of larger drugs)
  • improve drug retention (drug stay longer in the body = increase opportunity to interact with target)
  • reduce off target SE through targeting
  • increase dosing (can add more drugs in)
  • reduce frequency of administration → increase compliance
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13
Q

CNS drug formulations

A
  • solutions
  • suspensions (nano/microemulsions, liposomes /lipid bilayers, nanoparticles)
  • powders
  • gels (more viscous can last longer in the nose)
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14
Q

excipients

A

are ingredients aside from API, pharmacologically inert

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15
Q

diluent eg

A

water

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16
Q

buffer salts eg

A

(weak acid/base to maintain pH) - acetic and citric acids, acetate, phosphate

17
Q

pH adjuster eg

A

(strong acid/base) - NaOH, HCl

18
Q

preservatives eg

A

benzalknoium chloride, benzyl alcohol, chlorhexidine, chlorobutanol, parabens, phenylethyl alcohol

19
Q

tonicity adjusters eg

A

(salts) - KCl, NaCl

20
Q

stabilisers/ co-solvent (increase solubility of drug in diluent)

A

ethanol, ether, glycol, glycerol, glycine, PEG, glyceryl dioleate

21
Q

surfactant eg

A

glyceryl monoleate, lecithin, polysorbate, tyloxapol

22
Q

permeation enhancers function

A

increase absorption of drug

23
Q

viscosity modifiers eg

A

microcrystalline cellulose

24
Q

flavouring agents eg

A

menthol, saccharin sodium, sorbitol

25
Q

considerations for intranasal formulation

A
  • pH 4-7.4
  • tonicity 300-700 mOsm
  • volume 200uL max
26
Q

packaging and storage

A
  • container material should not have chemical or physical interactions with drugs and excipients
  • protect formulation from contamination and degradation
  • store in cool and low moisture environment, not in fridge/ freezer
27
Q

excipients in sumatriptan nasal spray:
- monobasic potassium phosphate
- anhydrous dibasic sodium phosphate
- sulfuric acid and NaOH (strong acid and base)
- purified water

A
  • monobasic potassium phosphate: buffer salts (since drug is ionisable, need to have buffering agent to control pH)
  • anhydrous dibasic sodium phosphate: buffer salts
  • sulfuric acid and NaOH (strong acid and base): pH adjusters
  • purified water: diluent
28
Q

why are there no tonicity adjusters in sumatriptan nasal spray formulation?

A

drug is providing the osmolarity hence there is no tonicity adjusters

29
Q

requirements for nasal spray

A
  • formulation must be stable with nasal spray
  • user friendly
  • reliability in use (mechanism cannot fail)
30
Q

advantages of nasal spray

A
  • single use → no need preservatives
  • nozzle bypass nasal vestibule (hair) → less drugs trapped by hair
31
Q

considerations for nasal spray

A

spray content uniformity (amt of drug delivered per pump), spray pattern and plume geometry

32
Q

nasal powder device (blow from mouth, powder enters nose) advantages & disadvantages

A
  • blowing avoids negative pressure and traps powder in nasal cavity → less drug lost
  • may cause irritation
33
Q

midazolam MOA

A

activation of GABA receptors

34
Q

SE of midazolam

A

can cause dependence (do not use more than max dose)

35
Q

excipients:
- ethanol
- PEG
- propylene glycol
- purified water

A
  • ethanol, PEG, propylene glycol → cosolvent (midazolam poorly soluble in water need cosolvent to increase solubility)
  • purified water → diluent
36
Q

in situ gels

A

Low viscosity solutions but increase in viscosity once administered → enhance retention time

  • activated by salt conc., pH, temperature

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