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Pharmacy Y3S1 > Oral Dosage Forms > Flashcards

Oral Dosage Forms Flashcards

1
Q

How do small lipophilic compounds permeate?

A

Paracellular water channels

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2
Q

How do lipophilic compounds permeate?

A

Transcellular Route

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3
Q

Are Class I drugs eligible for a Biowaiver?

A

Yes

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4
Q

Are Class II drugs eligible for a Biowaiver?

A

If weak acids, highly souble at pH6.8 pluss dissolution

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5
Q

Are Class III drugs eligible for a Biowaiver?

A

If very rapidly dissolving

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6
Q

Are Class IV drugs eligible for a Biowaiver?

A

No

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7
Q

When are drugs considered highly soluble?

A

Highest dose dissolves in <250ml water over pH 1-7.5

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8
Q

When are drugs considered highly permeable?

A

If >90% of the dose is absorbed

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9
Q

What solubility impairs solubilisation during formulation?

A

<10mg/ml

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10
Q

What form are BSC class I more clinically effective in?

A

Immediate release or controlled release

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11
Q

What effects does a low solubility have in vivo?

A

Decreased bioavailability
Suboptimal
Increased chance of food effects
Increased issues in patients with diseases - esp GIT problems relating to blood flow
More frequent incomplete release of drug
Higher inter-patient variability
Inability to optimise lead compounds
Harsh excipients required
Extreme basic or acidic conditions needed
Uncontrollable precipitation after dosing
Non-compliance due to dosing

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12
Q

Which factors affect solubility and permeability?

A 
Wettability
Surfactants
Particle size
Solid dispersions
Polymorphs
pH solubility
Soluble prodrugs
Complexation
Adsorbents
Viscosity
Degredation
Diluents
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13
Q

How can permeation be enhanced?

A

Absorption enhancing excipients
Efflux inhibitors
Lipid filled capsules
GI motility consideration

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14
Q

How can solubility be enhanced?

A 
Particle size reduction
Soluble salts
Solid dispersions
Self-emusifying systems
Surfactants
Nanoparticles
Cyclodextrin
pH diffusion layer
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15
Q

How can both solubility and permeability of a drug be enhanced?

A 
Prodrugs
Salt forms
CO-solevents
Solubilisation by surfactants
Lipid-filled capsules
Nonparticles
Liposomes
Lyophilisation
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16
Q

What is the structure of Cyclodextrins?

A

Hydrophobic interior
Hydrophilic exterior
Form complexes with hydrophobic compounds

17
Q

How are CD’s formed?

A

Supersaturating a CD solution with a drug and agitate

Kneading a drug/CD.solvent slurry to paste which is dried and sieved

18
Q

How can CD solubilising effect be improved?

A

Hydrophilic polymers (HPMC) so less CD needed for same amount of drug

19
Q

What is the disadvantages of CD’s?

A

Toxicity and stability issues

20
Q

What is the disadvantages of amorphous solid dispersions?

A

Unstable

Prone to recrystallisation

21
Q

How are amorphous compounds created?

A

Formulation with polymers
Spray dry using solvents or supercritical fluids
OR
Hot melt extrusion (soften polymer, add drug, mix as it flows through extruder. rapidly cool)

22
Q

Describe PEG as a Polar excipient

A

Can be used as a co-solvent in liquid-based formulations - prevent precipitation
Topical and parenteral admin
Acts as a wetting agent/enhances dispersion
Incorporated by solvent evaporation/freeze drying
Can combine with other excipients

23
Q

Describe Gelatin as a polar excipient

A

Both positive and negative charges

Used to improve the wettability of hydrophobic compounds when used as a granulating agent

24
Q

Describe Sugar glasses as a polar excipient

A

Parenteral and pulmonary use, GRAS for oral
Inulin + drug + freeze dry = sugar glass
Improves dissolution profile and stability
Used in the formulation of cyclosporin, diazepam, amoxicillin, bacitracin, tetrahydrocannabinol

25
Q

Describe Lipids as a polar excipient

A

Used in self emulsifying systems (lymphatic delivery)

26
Q

How does particle engineering improve solubility?

A

Reduce size = increased surface area
Can used lipid or anti-solvents to recrystallise which reduces particle size
Conventional communition and spray drying = mechanical stress

27
Q

What are the benefits are nanoparticle formulations of drug delivery?

A

Greater bioavailability - higher Cmax, AUC
Less variability with food
AUC proportional to dose

28
Q

How are nanoparticles created?

A

Micromilling with pysical and thermal stress = sub-microns
Piston gap methods with hydrodynamic cavitation = microns
Supercritical Fluids create by control of solubility using pressure and temperature in solvents such as CO2

29
Q

What are Supercritical fluids used for?

A

To produce different sizes and shapes of drug particles

30
Q

How do supercritical fluids work?

A

At a temperature above their thermodynamic critical points, they assume the properties of both a liquid and a gas

31
Q

What size can SCF solubilised drug particles re-crystallise at?

A

5-2000nm

32
Q

How are SCF’s manipulated?

A

At near critical temperatures SCF’s are highly compressible - moderate changes in pressure or temp can alter density, mass transport and solvating power - improving diffusivity and reducing viscosity and surface tension

33
Q

What role do non-ionic surfactants have in self-emulsifying systems?

A

Improve drug solubilisation and prevent drugs from precipitating out of the micro-emulsion

34
Q

What are Tweens and

Labrafil with high HLB used for in a self emulsifying systems?

A

Ensure immediate formulation of O/W droplets

35
Q

What are ethanol/PEG/propylene glycol used for in a self emulsifying systems?

A

Increase the amount of drug dissolved in the lipid base

36
Q

How are solid particles formulated into self emulsifying systems?

A

Suspension-dried

Produces a stable colloidal micro-emulsion suspension of sub-micron drug particles in a solid lipid matrix

37
Q

What is a self emulsifying system used for?

A

Poorly soluble, lipophilic drugs

38
Q

What does the presence of lipid in the duodenum stimulate?

A

Secretion of biliary lipids - generates colloidal micelles, mixed micelles and emulsion droplets

Pharmacy Y3S1 (14 decks)

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