Pharmaceutics and pharmaceutical Technology Flashcards
what are excpients
inert or inactive substances added in the manufacturing process.
role of excipients
-palable
-enhance patient compliance and acceptability
-faciliutate the handling ,preparation and usage of pharmaceutical products
Binders
-they are added to produce the mechanical strength of drug filler mixture.
-added to granules,tablets
-they assist the flow of granules
-they impact adhesion and cohesiveness on powders
examples of binders include
gum
starch
sucrose
gelatin mucilages
polymeric substances
what are disintegrants
added to compostion of a tablet or capsule to ensure that it can be broken up into fragments to improve drug dissolution
examples of disnitegrants include
maize starch
cellulose
sodiumcarboxymethylcellulose
suspending/thickening agents
-increase the viscosity of the dispersion medium to reduce the rate of sedimentation of particles and ensure uniform withdrawal of doses
what is the common example of suspending agent
Tragacanth
what are Glidants?
substances added to assist the uniform flow of granules and powders during tableting and into capsules.
some poplular examples of glidants include
talc
magnesium stearate
at 1-2% w/w
what are lubricants?
they prevent friction btw the powders and metal surfaces.
eg is magnesium stearate
what are stabilizers
added to enhance the stability of the dosage forms and minimize degradation. eg includes surfactants
surfactants are?
surface active agents that are absorbed causing a marked reduction of surface tensions.
critical micelle concentration
where surfactants form lamella structures to bring about stabilization of the dispersed systems
what is an amphipatic molecule
molecule that has both a hydrophilic and hydrophobic region
what are diluents(bulking agent)
they increase the bulk volume of powders and size of tablets
-used in potent drugs with narrow therapeutic window
examples of diluents include
lactose
sucrose
mannitol
sorbitol
calcium phosphate
calcium hydrogen phosphate
microcrystalline cellulose
dextrose
viscosity enhancing agents
-consists of hydrophilic polymeric substances
-used to enhance a palatable preparation, flow properties, ease of pouring through orifices
examples of viscosity enhancing agents
providone
hydroethylcellulose
carbomer
hydroxypropyl methylcellulose
sweeting/flavoring/perfume agents are used to
mask unpleasant taste,odour
eg include fruit juices,aromatic oils(peppermint and lemon plant spices)
colouring agents
used to improve attractiveness and ease of identification of the product
examples of natural colours include
Chlorophyll
carotenoids
anthocyanins
riboflavines
caramel
beetroot
-unstable because of variability in stability and chemical compostion
synthetic colours include
dyes and salts
emulsifying agents
substances added to achieve emulsification and stabilty of dispersed system
hydrophilic macromolecular colloids consists of
acacia,tragacanth,gums,starches
function of acacia is
stabilizes oil in water
what are suspending agents
sunstances added to increase the viscosity of the continous phase
wetting agents
they reduce interfacial tension btw solid particles and liquid
preservatives
used to protect pharmaceutical products,foods and materials against microbial spoilage
examples of preservatives include
benzoic acid
sodium benzoate
methyl paraben
propyl paraben
quaternary ammonium compounds
what are buffering agents
substances added to maintain chemical stabilty,control tonicity and ensure physiological compatibility
what is the PH of most body fluids
7.4 hence injections ,eye drops and nasal drops should be buffered to thsi PH to avoid incompatibility or irritations
Miscallenous excipients include
density modifiers
reducing agents
antioxidant
humectants
stabilizers
what is stability?
extent to which a product retains within specified limits and throughout its period of storage and use the same properties and characteristics that it had at the time of manufacture.
what is shelf life
period of time that a pharmacuetical product is to retain its chemical,physical and microbiological stability if stored correctly.
-it is the time taken for a drug to decay to 90% of its original conc
expiration date
date given on the packaging that represents the end of the shelf lufe
Factors that affect stability of pharmaceutical products
Temp-high temp accelerates chemical reactions
PH-drugs are stable at PH 4-8
moisture-water catalyses chemical reactions
Light-most drugs absorb UV light anf can lead to oxidation
Oxygen-exposure to oxygen affects stability
what is an overage?
adding 10% to what is stated on the label
what is zero order reaction?
reaction where the reaction rate is not dependent on the conc of material.
what is first order?
the reaction rate of change K is proportional to drug conc
classification of degradative pathways
-physical-changes in physical proeprties such as product appearance or reducing its effectiveness.
-chemical-most critical factor, max reduction of 90% of theeoretical value is accepted
Hydrolysis
the breakage or cleavage of a molecular bond by reaction with water
eg of drug molecules prone to hydrolytic degradation-esters,lactams,amide groups
Hydrolytic degradation of aspirin produces?
Salicylic acid and acetic acid
Hydrolytic degradation can be catalysed by
Hydrogen(H+) OR Hydroxyl(-OH) ions
steps to prevent hydrolysis
-including buffering agents to stabilize PH
-inclusion of surfactants
-prep of an insoluble salt form of the drug
-Formation of molecular complexes with esters
-replacement of water with alcohol or prolyhydroxyl solvents
-modification of chemical structures
what is oxidation
it is the removal of an electron from a molecule
initiation stage of oxidation
where free radicals are formed
RH- R. + H
Propagation stage
there is a marked increase in the conc of free radicals
R + O2 -RO2
RO2. + RH -ROOH + R.
Termination stage
depletion of O2
rate of reaction slows down and free radicals react to form un reactive end products
eg of drugs prone of oxidative degradation include
ascorbic
vitamins
steroids
hydrocarbon bonds
ways to minimize oxidation of pharm products
-inclusion of reducing agents
-replacmement of oxygen with suitable additives
-PH adjustment
-addition of antioxidants and chelating agents
-photolysis
what is photolysis
when drug molecules absorb wavelength(300-400) of light and results in degradation of such molecules.
eg of drugs prone to photolysis include-morphine,codeine,phenols,vitamin A and B.quinine,volatile and unstaurated oils
what is wet agglumeration
process of using a liquid binder to lightly agglomerate the powder mixtture.
amount of liquid should be controlled as over wetting will make granules too hard and underwetting too soft.
what is dry granulation
this process creates granules by light compaction of the powder blend under low pressures
what is melt granulation
when powders are agglumeeated using binders that melt in the process .
eg of binders used are beeswax,carnauba wax,poloxamers,polethylene glycols,parrafin wax,stearic acid,hydrogenated castor oil.
