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PHA333 > suppositories > Flashcards

suppositories Flashcards

1
Q

What are suppositories?

A

solid, single dose preparations

they contain 1 or more active substances dispersed/dissolved in a suitable basis that may be soluble or dispersible in water and may melt at body temperature

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2
Q

types of suppositories

A

rectal

vaginal (pessaries)

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3
Q

rectal blood circulation

A

superior rectal artery - main blood supply

haemorrhoidal veins (superior, middle, inferior veins) - drug absorption

drug absorption from inferior/middle veins - bypass 1st pass metabolism

absorption from superior veins - liver, 1st pass metabolism

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4
Q

SYSTEMIC effects of rectal suppositories

A

analgesia - paracetamol/NSAIDs

CNS disorders - diazepam

infections - ampicillin

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5
Q

LOCAL effects of rectal suppositories

A

haemorrhoids
constipation
colitis

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6
Q

dosage forms used rectally

A 
suppositories
ointments
enemas
tablets
soft capsules
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7
Q

advanages of vaginal route

A

high blood supply

avoidance of liver metabolism

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8
Q

disadvantages of vaginal route

A

low moisture content - affects disintegration of some dosage forms

pH varies - 3.5-4.5, hormonal stages (pregnancy, menopause)

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9
Q

local effects of vaginal route

A

infections - candida (thrush), trichomonas infections

local HRT

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10
Q

systemic effect of vaginal route

A

HRT - oestrogens, prostaglandins

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11
Q

dosage forms via vaginal route

A 
suppositories/pessaries
gels
creams
foam
tablets
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12
Q

body temp and suppositories/pessaries

A

vehicles melt/soften at body temp

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13
Q

g of med in rectal/vaginal suppositories

A

rectal

  • 1g infant
  • 2g child
  • 4g adult

vaginal
- 3-5g

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14
Q

ideal suppository base

A
  • melts/dissolves/disperses at 37 degrese C
  • non-irritating
  • physically stable during manufacture/storage
  • chemically stable and inert (compatible with drugs)
  • convenient to handle
  • high viscosity when melted
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15
Q

types of suppository bases

A
  1. oleaginous (fatty bases)
    - cocoa butter (theobroma oil)
    - cocoa butter substitutes
  2. water soluble/dispersible (hydrophilic bases)
    - glycerinated gelatin
    - PEG mixtures
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16
Q

advantages of oleaginous/fatty bases

A
  • appropriate for water soluble drugs
  • innocuous/non reactive
  • melt at body temp
  • less irritant than hydrophilic bases
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17
Q

disadvantages of oleaginous bases

A
  • FAs can become rancid
  • melt in warm weather
  • liquefy when certain drugs are incorporated
  • polymorphism
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18
Q

cocoa-butter (Theobroma oil)

A
  • obtained from roasted seeds of Theobroma Cacao
  • saturated triglycerides and unsaturated oleic acid
  • yellowish-white solid
  • has 4 polymorphic forms
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19
Q

polymorphic forms of cocoa butter

A

alpha, beta’, beta, gamma

  • diff crystal structures, same chem structure
  • diff physical properties
  • melting points diff
  • all forms convert to beta in days/1 week
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20
Q

cocoa butter substitutes

A
  • mixture of synthetic/natural vegetable oils
  • triglycerides of natural saturated fatty acids
  • fatty alcohols C10-C18
  • eg Witepsol H15, Wecobee, Dehydag, Cotmar, Fattibase
21
Q

composition of ondansetron suppositories (Zofran)

A

ondansetron 16mg

Witepsol S58 (cocoa butter substitute)

22
Q

composition of Alvedon suppositories

A

paracetamol 60/125/250mg

Witepsol H12

23
Q

advantages of hydrophilic bases

A

appropriate for lipophilic drugs

24
Q

disadvantages of hydrophilic bases

A

hygroscopic (need to absorb rectal/vaginal fluids)

slow dissolution

mucosal irritation

25
Q

glycerinated gelatin

A
  • mixture of glycerin and gelatin
  • hygroscopic
  • ratio of water:glycerins:gelatin
    - > 10:70:20
  • laxative purposes
  • vaginal preparations
26
Q

PEG base with:
96% PEG 1000, 4% PEG 4000

COMPARED TO

75% PEG 1000, 25% PEG 4000

A

base 1: (96%, 4%)

  • low mp, refrigerate in summer
  • rapid drug release

base 2 (75%, 25%)

  • higher mp
  • slower drug release
27
Q

types of macrogols

A

300-600 -> clear liquid, miscible with water, soluble in alcohol

> 1000 -> white waxy appearance, soluble in water

28
Q

how to package PEG

A

in tightly closed containers

they absorb water

can be stored without rifrigeration

29
Q

problems with PEG

A

incompatible with many drugs

membrane irritation - deplete cavity of fluids

30
Q

ortho-gynest pessary composition

A

estriol 0.5mg
benzoic acid - preservative
butylated hydroxytoluene BHT - antioxidant
PEG 400 - base hydrophilic
PEG 1000 - base hydrophilic
sorbitan monostearate - surfactant, enhances sol of drug during release
Witepsol S55 - base lipophilic, cocoa butter substitute

-> hydrophilic and hydrophobic bases together to adjust the solubility of the drug

31
Q

formulation considerations for suppository base properties

A

type

melting/dissolution characteristics

viscosity at 37 degC

32
Q

formulation considerations for drug properties

A
  • solubility of drug in base and rectal/vaginal fluids
  • solubility of drug in molten and cooled base
  • particle size
  • > dissolution rate
  • > physical stability
  • total amount of drug
  • displacement value
33
Q

what bases for liphophilic and hydrophilic drugs

A

lipophilic drug -> hydrophilic base

hydrophilic drug -> oleaginous base

34
Q

displacement value DV definition

A

mass of drug that displaces 1g of base

35
Q

When does displacement value DV apply?

A

when dug dispersed in the molten base

36
Q

excipients

A 
hardening agents
surfactants
non-hygroscopic agents
permeation enhancers
preservatives and antimicrobial agents
37
Q

hardening agents

A
  • prevent base leaking
  • when mp of fatty base is lowered by other ingredients

eg. beeswax, cetyl esters wax

38
Q

surfactants

A
  • help to break up suppositiry and disperse drug
  • increases wetting of base in rectal fluids
  • lipophilic base and/or drug

eg. Span, Tween

39
Q

non-hygroscopic agents

A
  • reduce water uptake
  • physical and chemical syability on storage

eg. colloidal silicon dioxide

40
Q

permeation enhancers

A

disrupt membrane calcium channels in rectal cavity

increase diffusion of drug

-> not in vaginal drug delivery

41
Q

preservatives & antimicrobial agents

A

prevent microbial growth in water soluble bases

42
Q

2 methoda of supposiroty manufacture

A
  1. moulding

2. compression

43
Q

moulding method manufacture

A
  • lubrication of mould
  • calibration of mould
  • melting of base and addition of medicaments in a heat tank
  • filling of moulds with molten mass
  • cooling
  • removal
  • > automated process
44
Q

compression method manufacture

A
  • base and medicaments mixed and heated together to a soft paste
  • paste forced though a cylinder to fill suppository die
  • appropriate for thermolabie (heat sen) drugs
45
Q

manufacturing considerations with theobroma oil/cocoa butter

A

controlled melting to get right polymorph

  • temp
  • rate of cooling
  • agitation
  • don’t heat above 35 C
  • heat enough to remove alpha, gamma, beta’, BUT KEEP BETA
  • can add beta seed crystals from stock
  • store at 28-30 C
46
Q

drug release from oleaginous/fatty base and hydrophilic base

A

oleaginous

  • melts and spreads
  • drug partitions from molten base

hydrophilic base
- absorbs water and dissolved fluids

47
Q

properties that affact release/diffusion

A

drug properties

  • pKa
  • partition coefficient

rectal/vaginal fluid properties

  • pH
  • volume
  • viscosity/composition

membrane permeability
contents
pressure from membrane wall

48
Q

QC of suppositories

A
  • appearance
  • drug content and uniformity of content
  • fragility
  • melting and dissolution behaviour

PHA333 (27 decks)

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