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PY366 Drug discovery > Formulation of selected molecular types for various delivery routes > Flashcards

Formulation of selected molecular types for various delivery routes Flashcards

1
Q

what is the difference between a drug substance and a drug product

A
  • drug substance is the active pharmaceutical ingredient
  • drug product is the most suitable dosage form for delivering the drug
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2
Q

what is involved in pre formulation

A
  1. identification and chemical information
  2. validated and analytical method
  3. solubility- aqueous/non aqueous
  4. physico-chemical parameters
    - pka
    -log p
    - particle size
    - melting point
  5. stability
  6. organoleptic properties
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3
Q

what are transdermal drug delivery systems

A

facilitate the passage of therapeutic quantities of the drug substances through the skin and into the general circulation to elicit their systemic effect

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4
Q

what are topical delivery systems

A

drug delivery to the skin or corneal membrane of the eye or ear
- drug acts locally to treat localised conditions

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5
Q

what are the advantages of transdermal and topical formulation

A
  1. ease of use by patient
  2. can be mass produced easily
  3. cosmetically elegant and appealing products
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6
Q

what are the disadvantages of transdermal and topical formulations

A
  1. not all drugs can be delivered by this route
  2. dosage control can be difficult
  3. amount of drug available for systemic action is limited to the drug physicochemical parameters
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7
Q

list the commonly used excipients

A
  1. solvents- water, buffers, ethanol
  2. oily formulation bases- WSP, liquid paraffin
  3. aqueous formulation bases (gelling agents)- carbomer, xanthum gum
  4. emulsifiers (surfactants)- tween 80
  5. antioxidants- vitamin E, ascorbic acid
  6. silicones- dimethicone
  7. dispersing agents- hydrated silica
  8. metal chelator- EDTA
  9. preservatives- methylparaben, sodium benzoate
  10. skin penetration enhancers- ethanol, propylene glycol
  11. lacquer resins- gantrez
  12. powders- starch
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8
Q

what are the basic rules for formulation design

A
  1. select excipients based on formulation type
  2. determine excipient compatibility with the API and other excipients
  3. use minimal number of excipients- less problems with formulation stability
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9
Q

describe the usual method of preparation for an ointment

A
  1. drug dissolved in solvent mixture
  2. heat liquid paraffin and WSP
  3. add drug solution to the molten base and cool with stirring
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10
Q

what are creams

A

semi solid preparations for external application

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11
Q

how are creams formulated

A

emulsions
- oil in water
- water in oil
- multiple emulsions
- drug is dissolved in either aqueous phase or oil phase

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12
Q

what are the advantages of cream formulations

A

better patient compliance as cosmetically elegant product

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13
Q

what is required in a formulation of a simple solution

A
  • buffer
  • formulation should be isotonic and sterile
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14
Q

describe the method of preparation of a suspension

A
  1. dissolve buffer in solvent
  2. add polysorbate80, preservative and HEC
  3. mix to form a uniform solution
  4. add API and mix thoroughly
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15
Q

what is a transdermal matrix patch

A

contains a polymeric matrix containing drug intended for systemic drug delivery

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16
Q

what is a transdermal membrane patch

A

contains a drug reservoir entrapped between backing and adhesive layers and a drug diffusion controlling membrane

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17
Q

what are the formulation requirements for a tablet

A
  1. API
  2. binder
  3. disintegrant/binder
  4. lubricant
  5. glidant
  6. filler
  7. tablet coat
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18
Q

what is the powder mixture tested for in a tablet

A

tested for powder flow
- Carrs index
- hausners ratio

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19
Q

what are the formulation characterisation tests for formulating a tablet

A
  1. friability
  2. disintegration
  3. hardness
  4. dissolution
  5. uniformity of weight
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20
Q

what excipients are usually found in a suspension

A
  1. API
  2. surfactant
  3. buffer
  4. viscosity modifier
  5. preservative
  6. solvent
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21
Q

what excipients are usually in a simple solution

A
  1. API
  2. preservative
  3. isotonic agent
  4. buffer
  5. surfactant
  6. solvent
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22
Q

what excipients are usually found in an aqueous gel

A
  1. API
  2. gelling agent
  3. preservative
  4. solvent
  5. co-solvent
  6. aqueous phase
  7. pH adjustment
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23
Q

what are the components of an aqueous phase cream

A
  1. solvent
  2. preservative
  3. aqueous phase
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24
Q

what are the components of an oil phase cream

A
  1. API
  2. solvent
  3. emulsifier
  4. oil phase
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25
Q

what are the components of an ointment formulation

A
  1. API
  2. solvent
  3. emollient
  4. hydrocarbon base
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26
Q

what is parenteral drug delivery

A

administration of a drug by injection through an alternative route such as
- sc
- IM
-IV

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27
Q

what are the advantages of parenteral drug delivery

A
  1. quick drug delivery and rapid onset of action
  2. ideal alternative when oral therapy is not possible
  3. used for both local or systemic
  4. implants and depot for prolonged action
  5. suitable for parenteral nutrition and for continuous medication
28
Q

what are the disadvantages of parenteral drug delivery

A
  1. can be administered only by trained medical personnel
  2. patient compliance could be a problem
  3. bypasses most of the bodys natural defence mechanisms
  4. nearly impossible to reverse effects once drug administered
  5. stringent manufacturing and packaging requirements leading to higher production costs
29
Q

what are the requirements of a formulation

A
  1. must be clean, pure and free from physical, chemical and biological contaminants
  2. product must be sterile
  3. good manufacturing practice
  4. product quality must meet stringent requirements
30
Q

what are the different types of formulations of parenteral drug delivery

A
  1. solutions
  2. suspensions
  3. liposomes
  4. emulsions
  5. nanoparticles and microparticles
  6. implants
31
Q

what are the different formulation sizes for parenteral drug delivery

A
  1. small volume parenteral products
    - single bolus injections suitable for IM, SC, IV
    - dose from 0.1ml-1.5ml
  2. large volume parenteral products
    - suitable for IV infusion
    - dose >100ml
    - drug and saline infused over time
    - parenteral nutrition
  3. implants
32
Q

what does the choice of small volume parenteral and large volume parenteral products depend on

A
  1. route of administration
  2. onset/duration of action
    - quick acting SVP
    - prolonged/continous duration- LVP
  3. concentration of drug in product
33
Q

what are the excipients that can be used for injections

A
  1. solvents
    - aqueous- water for injection
    - aqueous miscible- glycerol, ethanol
    - non aqueous- sesame oil
  2. buffers- salts
  3. preservatives
  4. antioxidants
  5. solubilising agents (surfactants)
  6. viscosity modifiers- methylcellulose
34
Q

what aqueous vehicles can be used for parenteral drug delivery

A
  1. water for injection- distillation or reverse osmosis process
    - free from particulates, bacteria and pyrogens
    - quick production to utility to minimise contamination
  2. water miscible solvents- used as cosolvents to increase solubility/stability
    - concentration of solvents depends on route of administration
35
Q

when are non aqueous vehicles usually used

A
  • for intramuscular depot injections
  • sustained release of drug
  • can be used for water insoluble drugs
36
Q

what are the disadvantages of using non aqueous vehicles

A

can cause irritation and topical allergic reaction

37
Q

what are preservatives used for

A

to prevent bacteria growth

38
Q

how should formulations be prepared in regards to pH

A
  • should be close to physiological pH (7.4)
  • formulations prepared at lower pH diluted in suitable IV infusion solutions before administration
39
Q

how does tonicity affect formulation

A
  • essential to maintain osmolality of final products (LVP)
  • hypertonic preferable to hypotonic
40
Q

give an example of a tonicity modifier

A

sodium chloride, mannitol

41
Q

what does the formulation of an injection include

A
  1. API and excipients
    - highest chemical grade
    - free of microbial and pyrogen contamination
    2.antimicrobial agents
    - added to multi dose units
    - compatible
    - effective concentrations
  2. antioxidants
    - metal chelator- EDTA
    - aqueous
    - lipophilic
42
Q

what is involved in the formulation of poorly aqueous soluble drugs

A
  1. pH manipulation
  2. cosolvents and non aqueous vehicles
  3. surfactants
  4. complexing agents
  5. emulsions
  6. stability of final product
43
Q

describe the formulation of suspensions as parenteral products

A

to control the rate of absorption
- IM depot injections
- absorption rate is dependant on rate of dissolution
- particle size is critical- should be less than 5um
- eg. cholera vaccine

44
Q

what are the advantages of pulmonary drug delivery

A
  1. non invasive drug delivery
  2. large absorption surface area
  3. very thin absorptive mucosal membrane
  4. quick acting
  5. rapid and quantifiable amounts of drug delivered to lungs
  6. can be both for local and systemic treatment
  7. avoids first pass metabolism
45
Q

what are the disadvantages of pulmonary drug delivery

A
  1. use of propellants required (CFC)- not environmentally friendly
  2. drug particle size needs to be strictly controlled
  3. drug and formulation stability
  4. drug safety
  5. absorbed proportion of deposited drug
  6. pharmacokinetics
  7. some devices require inhalation effort which requires coordination from patient
46
Q

give examples of pulmonary drug delivery

A

theophylline, salbutamol

47
Q

describe the formulation procedure for a nebuliser

A
  1. dissolve drug in water, followed by NaCl
  2. preservatives dissolved in PG
  3. mix both solutions with constant stirring
  4. aseptic manufacture or sterilise after manufacture
48
Q

describe the usual method of preparation of an MDI

A
  1. dissolve drug in ethanol
  2. transfer solution into the vial
  3. Seal the vial
  4. fill the vial with propellant
  5. can form single, 2 or 3 phase system
49
Q

give examples of propellants used

A
  • fluorinated hydrocarbons
  • hydrocarbons
50
Q

what are the requirements of the excipients used for an MDI

A
  • should be chemically inert
  • miscible with non polar solvents
51
Q

describe the method of preparation of a DPI

A
  1. mix drug and carrier particles and glidant in increasing amounts
  2. fill powders into capsules
  3. capsules packaged into blister packs
52
Q

give examples of carrier particles used for DPI

A
  • lactose
  • dextrose
53
Q

give examples of glidants used for DPI

A

magnesium stearate

54
Q

what is a suppository

A

a solid dosage form intended for insertion into body orifices where it melts, softens or dissolves and exert local or systemic effects

55
Q

what are the 3 main types of suppositories

A
  1. rectal suppository- inserted into rectum
  2. pessary- inserted into vagina
  3. urethral suppositories- inserted into urethra
56
Q

what are the advantages of rectal and vaginal drug delivery

A
  1. patients unable to take drugs orally
  2. infants and geriatrics
  3. 1st pass metabolism
  4. drug stability in gastric pH
  5. gut enzymatic stability
  6. drugs causing gastric irritation
  7. local or systemic effect
  8. can be used for prolonged action
57
Q

what are the disadvantages of rectal and vaginal drug delivery

A
  1. patient compliance- difficult to self administer for arthritic or physically compromised patients
  2. large scale production is difficult
  3. not all drugs delivered via this route
  4. patient to patient variation in response
  5. slow and incomplete absorption
  6. stringent storage conditions
58
Q

what excipients are included in suppositories

A
  1. suppository base
    - fatty or oleaginous bases
    - water soluble/miscible bases
    - miscellaneous bases
59
Q

what are the characteristics of fatty or oleaginous bases

A
  • hydrogenated fatty acids or vegetable oils
  • exhibits polymorphism
  • melts at body temperature
60
Q

what are the characteristics of water soluble/miscible bases

A
  • eg. glycerinated gelatin, PEG
  • dissolves and absorbed in the body
61
Q

what are miscellaneous bases

A

mixture of fatty and water soluble bases containing a surfactant

62
Q

what is the displacement value

A

number of parts by weight of drug that displaces 1 part by weight of base

63
Q

what is the equation for calculating the amount of base required

A

amount of base required for preparing suppositories= N x Y - (N x D)/DV
- N= number of suppositories
- Y= weight of mould
- D= weight of drug in each suppository
- DV= displacement value

64
Q

describe the process of preparing a suppository

A
  1. mix API with other ingredients
  2. melt base above its melting point
  3. mix API with molten base
  4. lubricate mould
  5. pour into mould
  6. allow to solidify
  7. remove excess from top and remove from mould
  8. pack individually
65
Q

what other methods of preparations can be used for making suppositories

A
  1. compression- carried out at room temperature
    - suitable for thermo labile API
    - dry mix ingredients thoroughly and fill and compress into mould
    - but shape can only be a cylinder
  2. hand rolling and shaping

PY366 Drug discovery (15 decks)

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