roldo exam content Flashcards
(158 cards)
1
Q
what are disperse systems?
A
two phase systems in which an insoluble or immiscible dispersed phase (e.g solid particles or liquid droplets) is distributed through a continuous phase
2
Q
what are the different dispersed systems?
A
dissolved, single phase and dispersed
3
Q
what are the advantages of solid oral dosage forms?
A
-convenient and clean
-light and compact (economic) as they are easy to transport and store
-dry (stable)
-accurate dose
-may give controlled release
-can mask taste
4
Q
what are the disadvantages of solid oral dosage forms?
A
-difficult to swallow
-difficult to dilute
-difficult for liquid drugs
5
Q
what are tablets?
A
solid preparations each containing a single dose of one or more active substances
-they are intended for oral administration
6
Q
how are tablets obtained?
A
by compressing uniform volumes of particles
-they sometimes have different shapes and the size varies from 50mg to 500mg
7
Q
what are the general properties of tablets?
A
strength:to withstands shock during manufacturing, packing, shipping dispensing and use
-efficacy:drug content must be bioavailable,release must be reproducible
-safety:chemically and physically stable,uniform in weight and in drug content
8
Q
what are the different types of tablets?
A
uncoated or coated
-soluble/dispersible or orodispersible
-effervescent
-chewable
-buccal
-sublingual
-gastro-resistant or enteric coated
-modified or controlled release
-oral lyophilisates
9
Q
why does nothing happen when enteric coated tablets reach the stomach?
A
the coating is not soluble in the acidic pH
10
Q
what are the different types of tablet excipients?
A
-diluents-form the bulk of the tablet
-binders-for granulation
-disintegrating agents-for drug release
-glidants-promote granule flow
-lubricants
-coating agents-protection
-colouring-helps patients differentiate between different tablets
-flavouring
11
Q
what do lubricants do?
A
prevent tablet from sticking to the die wall or punches in the tablet press
12
Q
what do tablet coatings do?
A
-protects the active ingredients
-organoleptic-taste,colour,smell
-improves product quality
-aids identification (e.g colour)
-protects the tablet during packaging/storing
-prevents contamination and dust problems
-can control drug release
13
Q
what are the different types of tablet coating?
A
-sugar coating-excipient=sucrose
-film coating-excipient=HPMC-hydroxypropylmethylcellulose (or hypromellose)
-press coating
14
Q
what are the advantages of sugar coating for tablets?
A
the appearance-rounded,highly polished tablets are produced
15
Q
what are the disadvantages of sugar coating for tablets?
A
-Multistage (time consuming)
-Difficult to automate
-Not for controlled release.
-increase tablet size by 30 – 50 %
-Indented logos not feasible
16
Q
what are the advantages of film coating for tablets?
A
-Increase tablet size by 2-3%
Can be automated
-Single stage process
-Good for controlled release
-Indented logos can be used
17
Q
what are the disadvantages of film coating for tablets?
A
-Environmental – extraction of organics into atmosphere
-Safety – explosion / fire / & toxic hazards (expensive to deal with)
-Solvent residues must be investigated
-Alternative aqueous route: hydrolysis causes problems, heating can destroy drug
18
Q
what are the advantages of press coating for tablets?
A
-separates incompatible materials (one in layer,one in core)
19
Q
what are the disadvantages of press coating for tablets?
A
-they are based on compaction of coating around pre-formed core.
-requires relatively complex, specialist equipment
20
Q
what are the 2 functional coatings?
A
-enteric coatings
-controlled release
21
Q
describe enteric coatings…
A
-insoluble at low pH therefore not attacked by HCL in the stomach
-sharp increase in solubility at higher pH e.g 5.2 for cellulose acetate phthalate coating
-Other materials:
polyvinylacetate phthalate and acrylic derivatives
22
Q
describe controlled release coatings…
A
they are polymers with restricted water solubility or permeability
23
Q
what are the three mechanisms of controlled release?
A
-Diffusion control-rate of release controlled by the rate of diffusion of drug through the coating
-Erosion-coatings designed to erode gradually
-Osmosis-osmotic pressure used to control release of drug
24
Q
what is a capsule?
A
a capsule consists of a dose of a drug enclosed in a water soluble shell made of gelatin
25
why is gelatine used in capsules?
because it is:
non toxic
soluble at body temp,
has good film forming properties
-changes from a gel to solid at temps just above room temperature
26
what is a hard gelatine capsule?
hard capsule consists of gelatin and water with dyes and pigments to add colour
-it comprises of a two piece shell (body and cap) which lock together
27
what must the material going in a hard gelatine capsule need to be?
-accurately filled
-not react with gelatin (must not contain aldehydes or water)
-must not leak out of the shell
28
what are the different fill materials?
-powders
-Granules
-Pellets
-Tablets
-Pastes
-Low viscosity,non aqueous liquids
29
what are soft shell capsules?
-capsules that consists of a solid flexible shell surrounding a liquid or semi-slid fill
-permits liquids to be presented as solid dosage forms
-the drug is protected from water and oxygen
30
what does the shell of soft shell capsules comprise?
comprises gelatin,plasticiser (usually glycerol,sorbitol or propylene glycol),water,preservatives,dyes
31
what are soft gelatine capsules (soft gels)?
-one piece sealed shells
-they are round,oval,oblong or tubular in shape
-they are formed,filled and sealed in one go
32
how much non-aqueous liquid are soft gels filled with?
with 0.1 to 0,8mL of non-aqueous liquid
-liquid can be hydrophilic (e.g polyols surfactants) or lipophilic (i.e mineral or natural oils eg cod liver oil)
-hydrophilic oils can allow rapid attainment of therapeutic drug levels (e.g with temazepam)
33
what are the liquids that soft gels can be filled with?
-the liquids can be hydrophilic (e.g polyols surfactants) or lipophilic (i.e mineral or natural oils eg cod liver oil)
-hydrophilic oils can allow rapid attainment of therapeutic drug levels (e.g with temazepam)
34
what are the problems with soft gels?
-migration of fill material through the capsule shell (sweating)
-migration of shell contents the other way which can possibly cause instability
-both soft and hard capsules are unstable for drugs that are unstable in the presence of moisture
-moisture in atmosphere may cause the shell to soften and break
-dry conditions may cause cracking
35
what are the factors that can influence the choice of capsule or tablet?
-company policy
-market research
-competitor products
-production preferences
-equipment available
-production costs
-required unit dose
-dissolution rate
-compression characteristics
-particle size
-stability
36
what are lozenges?
-they stay in the mouth for 10-15mins
-often release an antibacterial or anaesthetic (local effect)
37
what are chewable tablets
tablets designed to be broken down rapidly in the buccal cavity by action of the teeth
38
what are the properties of chewable tablets?
-mannitol is often used for a cooling taste
-a flavouring agent is frequently used
-no disintegrant
-no need for all ingredients to be water soluble
39
what are the properties of lozenges?
-they contain no disintegrate
-diluents are selected for them to ensure they have a smooth texture and pleasant taste
-sugars (e.g sucrose/glucose) are often used
40
what are dispersible tablets?
tablets that must disintegrate rapidly in cold water to produce a suspension for ingestion
-it is paramount the disintegrate is effective in water
41
what are soluble tablets?
tablets that are formulated to dissolve in water, so all ingredients must be highly soluble
42
what are orodispersible tablets?
tablets designed to disintegrate in the mouth
43
what are effervescent tablets?
-tablets that give rapid disintegration
-sucrose is hygroscopic therefore often used as a sweetener to increase stability
44
why are standard lubricants not used for effervescent tablets?
because the lubricant magnesium stearate slows the access of water and leaves a scum on the surface of water so sodium lauryl sulphate is often used
45
what are sublingual and buccal tablets?
tablets that are absorbed though the mucosa and passed to the jugular vein, hence bypassing the GI tract and liver
46
what are the properties of sublingual and buccal tablets?
-the tablets should not disintegrate
-rapid dissolution is required
-they help to avoid unpleasant tastes
47
what is the definition of solubility?
-the maximum amount of solute that dissolves in a given amount of solvent at a particular temperature and pressure
48
what factors can affect the solubility of a drug?
-structural features
-hydration and solvation
49
what are the two aspects of the structural features factor that affects solubility?
1-molecular surface area/molecular weight
2-hydrophobic/hydrophillic ratio and the position of substituents
50
how does molecular surface area affect solubility?
-it determines the number of solvent molecules that can pack around the solute molecule
-linear or branched structure affects the surface area
-boiling/melting point reflect the interactions within the molecules-higher the boiling/melting point=reduced solubility
51
how does molecular weight influence solubility?
-increasing the molecular weight decreases solubility
52
how does the hydrophilic/hydrophobic ratio affect solubility?
-polar and non polar portions of a drug can interact in different ways with the solvent
-the greater the area of the hydrophilic portion relative to the area of the hydrophobic portion the greater the aqueous solubility
-the distribution of the functional groups can also determine how the molecule interacts with solvent molecules
53
how can the solubility of a drug be manipulated?
by adding solubilising groups to the structure
-the three main aspects that are considered are:
*the type of group added
*whether the reaction is reversible or irreversible
*the chemical route of introduction/methods of introduction
54
what can the addition of polar groups do to solubility?
-can enhance the solubility of the parent compound in water
55
what are the highly polar functional groups?
-alcohol
-amine
-amide
-carboxylic acid
-sulphonic acid
-phosphorous oxyacid
56
what are the less polar functional groups?
-ethers
-aldehydes
-ketones
-esters
57
how does a reaction being reversible or irreversible affect solubility?
-a reversible link can be used to change the solubility temporarily they use the ability of endogenous enzymes of chainGph to break the bond with new functional groups and release the drug
58
how does the chemical route of introduction/method of introduction affect solubility?
-water solubilising groups can be introduced at any stage in the synthesis or post synthesis and consideration often needs to be given to the protection of groups already present in the molecule
59
what is a partition coefficient?
-it measures the way a compound distributes itself between an organic (lipid phase and an aqueous phase)
-the activity of a drug can often be correlated with partition coefficient and this can be used as a predictive tool
60
what is used to work out the partition coefficient?
-the log value in which the ratio of the concentration of unionised compounds at equilibrium between the organic and aqueous phases is looked at
61
formula for partition coefficient…
logP=log10[unionised compound]octanol/[unionised compound]water
62
what does it mean if log p is a value between -1 and 1?
-it is a polar compound
-it has good aqueous solubility
-it has poor lipid solubility
-it has poor absorption and distribution
63
what does it mean if log p is a value between 2 and 4?
-a compound of intermediate polarity
-there is a good balance between aqueous and lipid solubility
-there is good absorption and distribution
64
what does it mean if log p is a value between 4 and 6?
-it is a non-polar compound
-there is poor aqueous solubility
-there is good lipid solubility
-there is an accumulation in lipid-rich environments
-there is slow excretion
65
what is the most common method for determining logP?
-shake flask method
-the candidate drug is shaken between octane and water layers and an aliquot is taken and analysed
66
what is the value of the partition coefficient affected by?
-temp
-pH
-nature of the solvent
67
what are micelles formed by?
surfactants
68
what are surfactants?
-amphiphillic molecules that have a hydrophilic head and a hydrophobic tail
69
what do micelles do in water?
-they arrange in order to minimise the contact between the hydrophobic tail and the solvent
-at low concs they align on the surface of water
-at higher concs they self-assemble to form micelles
-hydrophobic drugs are entrapped in the core of the micelles
70
what are liposomes formed by?
-phospholipids
71
what is the structure of phospholipids?
-as surfactants the are amphiphilic and have a hydrophilic head and two hydrophobic tails
72
what do liposomes do in water?
-they self assemble to form a lipid bilayer
-they can solubilise hydrophobic drugs in the bilayer
-they can solubilise hydrophilic drugs in the water core
73
what do liposomes do in general?
-they are used to encapsulate drugs that are toxic or labile
74
what does osmotic pressure depend on?
-the concentration of solute in solution
-as micelle form at the addition of each molecule of surfactant there is no increase of number of entities in solution
75
what are cyclodextrins used for in special dosage forms?
to enhance the solubility, stability and bioavailability of drugs
76
what is the relationship between micelles and surface tension?
-positioning of surfactants on liquid surfaces breaks solvent-solvent bonds reducing surface tension
-once micelles are formed no more surfactant place themselves on the liquid surface
77
why are dosage forms developed?
for
-safety
-convenience
-efficacy
-accuracy
-reproducibility
-convenience
78
how is a dosage form made?
-active pharmaceutical ingredient (API) + excipients
79
what are excipients?
give examples
non active ingredients of various functions e.g
-solubilising
-preserving
-adding flavour
-avoiding oxidation
80
what factors influence the choice of dosage form?
-patient
-disease
-setting
81
what are the advantages of the oral route?
-simplest route
-patient compliance
-self administration
-safest route (if used properly)
82
what are the disadvantages of the oral route?
-onset of slow action
-absorption may be irregular from GIT
-there can be degradation of drugs due to enzymes and other secretions
-the first past effect decreases the drug concentration
-drug solubility may be altered due to interaction with other substances
-gastric emptying may vary due to food, drugs,disease etc
83
what is the sublingual route?
-involves the area under the tongue
84
what is the buccal route?
-it involves the area between the upper lip and gum or on the cheek
85
what is the difference between the sublingual and buccal route?
-the sublingual route has a fast onset of action but a shorter duration the buccal route has a quick onset but longer duration of action
86
what are the advantages of the buccal route?
-saliva facilitates the dissolution
-drugs are absorbed into circulation
-the first past effect is avoided
-drugs can be administered to unconscious patients
-antiemetic drugs may be administered via this route
87
what are the advantages of the rectal route?
-can be used when the oral route is unsuitable
-can be used with uncooperative patients such as children or babies
-it is useful if a drug causes GI irritation
88
what are the disadvantages of the rectal route?
-absorption is irregular and unpredictable
-less convenient
-there is low patient acceptability in the UK
89
what is the topical route?
-it involve the skin used as a site of administration
-there is a local effect
-there is also a systemic effect so there is no first pass effect
90
what is the difference between local and systemic effect?
-the local effect targets specific areas of the body to achieve localised effects, while systemic effect delivers medications into the bloodstream for distribution throughout the body
91
what are the different dosage forms included in the vaginal route?
-pessries
-tablets
-capsules
-solutions
-sprays
-creams
-ointments
-foams
92
what are the parenteral route dosage forms?
-subcutaneous
-intramuscular
-intravenous
-transdermal
-implantation
93
what is the inhalation (pulmonary) route?
-involves the nose or mouth
-can be a systemic or local effect
-predominantly used for local effect e.g asthma
-smaller dose is needed
-large surface area required
-there are less side effects
94
how is the nasal route?
-it has a local effect
-it is good vasculature for systemic effect
-it avoids first pass metabolism
95
what are emulsions?
-2 immiscible liquids, one is uniformly dispersed through the other
96
what do pharmaceutical emulsions do?
-formulate oil and water soluble drugs together
-enhance palatability of oils by disguising taste and oiliness
97
what are the different emulsion types?
-oil in water (o/w)
-water in oil (w/o)
-water in oil in water (w/o/w)-has delayed action
97
oil in water
-oral and iv administration
-topical,less greasy, easily washed off the skin,cosmetically acceptable
98
water in oil (w/o)
-intramuscular
-topical-rubs more easily into the skin
-occlusive effect, hydrates skin (emollient)
99
what are the three parts to the formulation of emulsions?
-oil phase
-water phase
-emulsifying agent
100
how is the emulsion type determined by the solubility of the emulsifying agent?
-if the emulsifying agent is more soluble in water then the emulsion type is o/w
-if it is more soluble in oil then the type is w/o
101
when does a phase inversion occur?
-if the solubility of an emulsifier is altered by addition of a chemical (emulsifying agent)
102
what are the ideal properties of emulsifying agents?
-colourless
-odourless
-tasteless
-non-toxic
-non-irritant
-produce stable emulsion at low conc
103
what are the natural types of emulsifying agents?
-polysacharrides-acacia,tragacanth,pectin,starch,carrageenan
-semisynthetic polysaccharides
-sterol containing substances
104
what does acacia do?
-forms a thick film at interface between oil and water to prevent coalescence
-it is best for oral emulsions and is too sticky for external use
105
what does tragacanth do?
-increases viscosity and prevents creaming
106
what do semisynthetic polysaccharides include?
-low viscosity methycellulose and carboxymethylcellulose which will form a o/w suspension
107
what do sterol containing substances include?
-beeswax,wool fat and wool alcohol
-hydrous wool fat made up of 7 parts wool fat and 3 parts water
-they act to form w/o emulsions
108
how do you choose an emulsifying agent?
-it is determined by the active ingredient and the use of the product (external or internal )
-natural polysaccharides and non-ionic emulsifying agents are used for internal preparations
-only certain non-ionic surfactants are used for parental use
-acacia is not used for products being made for external use
109
how are natural polysaccharides and non-emulsifying agents?
-non-toxic and non-irritant
-soap emulsions irritate the GI tract and have a laxative effect
-taste should be bland and palatable
-polysorbates require flavouring agents
110
give some non-ionic surfactants that are used for parenteral use?
-lecithin,polysorbate 80,gelatin,serum albumin
111
what is the relationship between the HLB value and the surfactant used in the emulsion?
-HLB>9=surfactant with lipophilic character
-HLB between 9 and 11=surfactant with intermediate character
-HLB>11=surfactant with hydrophilic character
112
what are the steps for the formulation of emulsions?
-water phase
-oil phase
-emulsifying system
-antioxidants-soluble in oil phase
-antimicrobial preservatives-free from toxic effects, odour and taste
-colouring and flavouring-only internal preparations are flavoured
113
how are antimicrobial preservatives?
-they are bactericidal not bacteriostatic
-have rapid action, wide antibacterial spectrum over wide pH and temp range
-partition into water phase but also into oil phase
-if the oil phase is increased the concentration in the water phase will decrease
114
what can affect the stability of emulsions?
-cracking (breaking coalescence)-interfacial film broken
-creaming-emulsion separated based on density
-flocculation
-phase inversion-(conversion of o/w emulsion to w/o or vice versa
115
what ingredients are used in the water phase of skin preparations?
water phase includes water, ethanol,macrogols
116
what ingredients are used in the oil phase of skin preparations?
-mineral oils-soft white or yellow paraffin, liquid paraffin, hard paraffin
-vegetable oils e.g peanut, caster or coconut oil
-synthetic oils-e.g silicone oils
117
state some o/w emulsifying agents
ANIONIC-sodium lauryl sulphate
CATIONIC-centrimide emulsifying wax BP
NON-IONIC-non-ionic:cetomacrogol 1000 emulsifying wax
-cetostearyl alcohol
118
what are the steps for the formulation of creams?
-melt all oily components in a water bath at 60*c-add the oil soluble drugs here
-dissolve all hydrophilic components in H2O and warm up to 60*c-add the water soluble drugs here
-mix the two phases and stir until cold-unstable and insoluble drugs should be added by trituration here
119
what are the steps for the formulation of ointments?
-weigh the solid excipients p
-melt the excipients in an evaporating basin (60-70*c) starting with the waxy ones-soluble and stable drugs should be added here
-stir until cold,continously to avoid lumps, gently to avoid air bubbles-less stable drugs should be added here
-ointment-here it is unstable and difficult to disperse drugs (inclusion by trituration)
120
what is the definition of packaging?
-the package is the economical mean of providing presentation, protection,identification/information,containment,convenience/compliance to the drug during storage,carriage and display use
121
what do pharmaceutical companies aim to do when developing packaging?
-aim to develop packaging that has the minimum overall cost, they will aim at maximising sales and maximising consumer confidence
122
what does cheap and expensive packaging result in?
-cheap packaging=poor sales and low profitability
-expensive packaging=more sales
123
what does packaging provide protection against?
-Climate – surrounding atmosphere, temperature, humidity
- Microbiological hazards – infestation by bacteria, moulds, yeasts
-Biological hazards – insects, rodents, human pilferage, etc.
-Chemical hazards – interaction and exchange between product and pack
-Use – professional or patient misuse
123
how is primary packaging?
-predominately functional, i.e. blister pack, a pouch, etc.
- Primary function to preserve the integrity of a dosage form, i.e. chemical and physical stability, robustness during transport and storage, etc
124
how is secondary packaging?
- controlled by legislation in most countries
- presentation and protection of the product
- includes information leaflets and any dispenser
125
what high quality standards does the protection provided by the package contribute to?
-safety-childproof closure, tampering evidence, give correct and clear instructions
-uniformity of dose-dispensers, single doses
-reproducibility-between batches
-integrity-of dosage form and package
purity-no contamination, tampering evidence
-shelf life-good packaging can improve stability and prolong shelf life
126
what are the pharmaceutical applications of suspensions?
-drugs with low solubility can be formulated as suspensions
-they are easier to swallow than solid dosage forms=improved patient acceptability
-drugs with unpleasant tastes in their soluble form can be formulated in more palatable insoluble form
-the rate of absorption is faster than from the solid oral dosage form
-it improves stability
127
why are intramuscular, intra-articular or subcutaneous injection formulated as suspensions?
-to prolong release
128
what are the properties of a good suspension?
-ready redispersion of sediment which forms during storage
-after shaking, particles stay in suspension long enough for accurate dose
-suspension is pourable
-suspension is free from gritty texture-particles are small
129
what are the excipients required for the formulation of suspensions?
-suspending agent
-wetting agent
-preservative
-colouring (if required)
-flavouring (if for oral administration)
-sweetening (if for oral administration)
-vehicle (water)
130
what are the steps for the formulation of suspensions?
-tare bottle
-grind solids (insoluble) down into the powder using a mortar and pestle and the geometric addition technique
-add suspending agent and mix-not too much pressure to avoid gumming or caking
-add little liquid to make a paste (wetting agents first)
-gradually add water until suspension can be poured into tarted bottle
-rinse pestle and make up volume
131
how do you form suspensions from tablets or capsules?
-obtain as much physical, chemical and microbial info as possible
-crush tablet or empty capsule in mortar
-add suspending agent
-form paste with vehicle and dilute to suitable volume-in preservative or flavour
132
how are diffusible solids?
-insoluble solids that are light and easily wetted
-they mix readily with water
-they are dispersed long enough for an adequate dose to be measured
133
how are indiffusible solids?
-not easily wetted
-may form large porous clumps
-will not remain in the suspension for accurate dose
-may not redisperse easily
134
what must you aim to have when it comes to the prep of suspensions?
-deflocculated suspensions with sufficient viscosity to prevent sedimentation
-flocculated suspension with suitable combination of rate of sedimentation and pourability
134
what are the wetting agents for the oral formulation of suspensions?
-ethanol,glycerol,glycols and syrup
135
what is the wetting agent for the external preparations of suspensions?
-sodium lauryl sulphate
136
what is the role of suspending agents in the formulation of suspensions?
-they are viscosity enhancers
-they may ind to medicaments making them less bioavailable
-thixotropic behaviour
137
what are the different categories of suspending agents?
-natural polysaccharides
-synthetic polysaccharides
-clays
-synthetic thickeners
-miscellaneous compounds-gelatin
138
give examples of natural polysaccharides
-tragacanth
-acacia
-alginate
-guar gum
139
give examples of synthetic polysaccharides
-they are derived from natural occurring polysaccharide cellulose
-methycellulose
-hydroxyethylcellulose
-sodium carboxymethylcellulose
140
give examples of clays?
-bentonite
-magnesium aluminium silicate (external preparations)
141
give examples of synthetic thickeners
-carbomer (Carbopol)
-colloidal silicon dioxide
-they are introduced to circumvent variable quality of natural products
142
how do you preserve suspensions?
-water can be a source of contamination so avoid high water content
-you need to choose a suitable preservative for internal or external preparation:chloroform water, benzoic acid and hydroxybenzoates
143
what are rectal preparations intended for?
-rectal use in order to obtain a systemic or local effect or they may be intended for diagnostic purposes
144
what are suppositories?
-solid,single dose preparations, the shape, volume and consistency of suppositories are suitable for rectal administration
144
what are vaginal preparations intended for?
-they are liquid, semisolid or solid preparations intended for administration to the vagina in order to obtain a local effect
-they contain 1 or more active substances in a suitable basis
145
how many active substances do suppositories contain?
-one or more and they are dispersed or dissolved in a suitable basis
146
what excipients can be added to suppositories?
-if necessary and authorised by the competent authority, excipients such as diluents, adsorbents,surface active agents, lubricant,antimicrobial preservatives and colouring matter may be added
147
how are suppositories prepared?
-compression or moulding
-sometimes the active substances are ground and sieved through a suitable sieve
-the medicated mass is sufficiently liquified by heating and is poured into the suitable mould
-the suppository solidifies on cooling
148
what excipients are available for the process of the production of suppositories?
-hard fat
-macrogols
-cocoa butter
-gelatinous mixtures consisting of gelatine,water and glycerol
149
what are the 4 main steps of formulating and compounding?
-mould preparation
-base preparation(DV calcs)
-prep of the active drug
-mixing and pouring
150
what happens in mould preparation?
-the mould must be clean and dry
-Lubrication may be needed-glycerin (inc fatty acids) and mineral oil (inc hydrophilic bases)
-mould needs to be equilibrated at room temp before use
-Each mould has a specific capacity
-Moulds are filled by volume so not all moulds and all bases give 1g suppositories
-Each mould needs to be calibrated
151
what happens in base preparation?
-the temperature of melting must be controlled depending on the base used
-the amount of base needed will depend on the amount of drug included-displacement value calculation
152
what happens during the preparation of the active drug?
-the drug ideally needs to be included as a powder as liquids occupy too much volume
-inclusion of liquids might require the use of emulsifiers to form an emulsion
-Powders are included by:direct mixing when soluble in the base,trituration when insoluble in the base
153
why is it important to reduce the particle size of the powder during the pre of the active drug?
-to improve the dispersion in the base
154
what happens during the mixing and pouring step?
-enough mixing time needs to be allowed in order to have a homogeneously dispersed drug
-continuous mixing needs to happen until there is an increase in viscosity which indicates that the base is about to set (congealing point)
-base needs to be poured into the first cavity of the mould
-the cavity of the mould needs to be overfilled to allow for shrinkage
-then move to the next cavity without stopping pouring to avoid the formation of layers
-trim the excess the solidified
-allow to cool
