Factors to consider when designing dosage forms, including drug and formulation factors.

1. George Wild Science of Medicines
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The Design of Dosage Forms
On a basiclevel,amedicine will containnotonlythe active pharmaceutical ingredient(the drug) but
a host of otheradditives(excipients) thatwillmodifythe physical and/orchemical behavioursof the
dosage form.Excipientsare carefullyselectedin preformulationtoachieve the bestpossible
medicine andwill usuallybe presenttorectifyproblemsthatone of the otherconstituentscauses
(oftenthisisthe drug).Withthisinmind,itcan be possible tohave apure or nearlypure drugina
medicine, asexcipientsdon’ttendtobe addedunlesstheyare actuallyneeded,forpharmacological
as well aseconomicreasons.
A dosage formshouldseektoprovide auniform, repeatable andsafe dose of drugtoeach patientto
achieve aneffectwhichhastherapeuticbenefittothe patient.Thisrequiresthe medicine tobe
appealingtothe patient(i.e.notdisgustingflavoursfororal preparations)andforthe response
withinthe patienttobe unifiedacrosspopulations.The latterisnotreallywidelyachieved due to
patientvariationingenetics,metabolicactivityanddisease/illnesspresence orseverity.Excipients
such as viscositymodifiers,organolepticmodifiers,preservatives,stabilisersandsolventsare usedto
achieve this.
Route of Administration Dosage FormsAvailable
Oral Solution,suspension,syrup,linctus,
elixir,gel,powder,tablet,granule,
capsule
Topical Solution,lotion,suspension,cream,
gel,ointment,foam, transdermal
patch
Rectal Suppository,cream, powder,solution,
ointment
Respiratory Aerosol (solution,suspension,
emulsion,powder),spray,inhalation
Eye Solution,ointment
Nasal Inhalation,solution
Ear Suspension,solution,cream, ointment
The dosage form will reflectthe solubilityof the drug,the clinical indicationforwhichitisused,the
desiredbioavailability,particle size andotherpharmacokineticproperties.Multiple dosageformsfor
the same drug are common,whichreflectsboththe differentindicationsforwhichadrugis
prescribedandthe differentcharacteristicsthe drugpossesseswithmodification.Dosage formsfor
medicinal productsarisingfrombiotechnologywillneedtoconsiderthe macromolecularnature of
the product as well assome specificbiological andchemical properties.Assuch,biotechnological
productsare formulatedprincipallyforuse viaparenteral andrespiratorydelivery,whichlimitsthe
choice of excipientsfurther.
Dosage formsshouldtherefore take intoaccount;the biopharmaceutical propertiesorabsorption,
distribution,metabolismandelimination;the physical andchemical propertiesof the drugproduct;
and the therapeuticconsiderationssurroundingclinical indication,patientattitudesandadherence
issues.

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Biopharmaceutical Aspects of Design
The biopharmaceutical factors of dosage formdesignwill considerthe physical,chemical and
biological aspectsof the drug,whichhave implicationsforthe absorptionof the drugacross
biological membranes,it’sdistributionwithinthe body,the extentandrate at whichthe drug is
metabolised,andthe rate of eliminationfromthe body(inurine,faeces,sweatandthroughthe
lungs) eitherinmetabolisedorunchangedform.
In orderfor a drug to be absorbedbythe bodyit mustfirstbe insolution,whichnecessitatesa
degree of aqueoussolubilityfromthe drug.Once inthe body,the drug will be takenupbyeither
passive diffusionorcarrier-mediatedtransport.The rate of diffusioninthe bodyisinfluencedbythe
degree of ionisationof the drug(as nearlyall drugsare weakacids or bases) andthe lipophilicityof
the drug. Dependingonthe route of administration,the drugwill eitherbe presentatitstargetsite
or needtotravel there inthe circulatorysystem, commonlythe latterwillhappenregardlessof the
route of administration.Giventhenthatthere are variousroutesof administrationandvarious
dosage forms,there are differencesbetweenthe onsetsof actionthatdependonthese twofactors.
Intravenousinjectionsare byfar the quickestactingroute of administrationbecausethe drugis
injecteddirectlyintothe bloodstream(givingit100% bioavailabilitytoo).Intramuscular,buccal,
subcutaneous,rectal andrespiratoryroutesof administrationare alsofast-actingdue tothe fact
that the drug bypassesfirst-passmetabolisminthe liveranddoesnothave topass throughthe
gastric systemorthe skin.
Thoughsome drugs maybe betterthanothersat beingabsorbedordistributedinthe body,all drugs
are essentiallyforeignbodiesandwill begintobe distributed,metabolisedandeliminatedassoonas
theyenterthe body.
Time of Onsetof Action Dosage Forms
Seconds Intravenousinjections
Minutes Intramuscularandsubcutaneous
injections,buccal tablets,aerosols,
gases
Minutesto hours Short-termdepot, solutions,
suspensions,powders,granules,
capsules,tablets,modified-release
tablets
Several hours Enteric-coatedformulations
Days to weeks Depotinjections,implants
Varies Topical preparations
The most commonroute of administrationisthe oral route,primarilybecause itissimple,reliable,
safe and providesalarge surface areaoverwhicha drugmay be absorbed(throughthe various
epitheliaandmucosainthe GI tract).However,manydrugs suchas proteins are notsuitable tobe
usedorallydue tothe enzymesandacidspresentinthe stomach(thisislessonan issue forthe small
numberof drugs that maybe takenorallyfora local effectinthe mouth).The low pH of the stomach
can alsopose problemsforbioavailabilityanddrugactionbecause of the effectithason degree of
ionisationandlipophilicity.Othersubstancespresentinthe stomachsuchas foodwill ofteninteract

3. George Wild Science of Medicines
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withdrug molecules,whichcanrenderthemtherapeuticallyinactive,reduce effectivenessorcould
evencause unwanted adverse effects.
The gastric emptyingtime isanotherfactorthatwill affectthatrate and extenttowhicha drug is
absorbedinthe GI tract. If gastric emptyingisslow,thendrugsthatare inactivatedormodifiedby
the gastric juiceswill undergodetrimental change,anddrugsthatare absorbedinthe intestine have
a delayedonsetof action.
 Tabletsare the mostcommonoral dosage formand consistof a knownquantityof the drug
compactedwithotheradditivessuchasdisintegrantsthatwill improvedissolutionand
absorptioninthe GI tract. Oftenthe tabletsare coatedwitha filmthatwill improve
organolepticpropertiesof the medicine,improve stability,protectitfromenvironmental
damage (suchas from pH or moisture) ormodifyitsreleaseinthe GItract.
 Capsules will containthe druginpowderedform, aswell asappropriate fillermaterialsthat
can increase dissolutioninthe gut.Theymayinsteadcontainmicroemulsionsorsemi-solid
fillings,butwill alwayscome inahard/softgelatine orpolymericshell thatrupturesor
dissolvesinthe stomach.
 Suspensionscontainfinelydividedparticlessuspendedinanappropriate (oftenoilyvehicle).
Thisdosage formis useful foruse whenusingthe drugintabletor capsule formisin
appropriate,andforpatientswhohave difficultyswallowing.The large surface area
presentedbythe finelydividedparticlesinasuspension improvesthe onsetof actionand
drug dissolutionandabsorption.
Rectallyadministereddrugsare insolution,suppositoryoremulsionformandare sued
advantageouslyoversome otherroutesof administrationdue tothe factthat the drug may pass
directlyintosystemiccirculationwithoutgoingthroughhepatoentericmetabolism,whichisuseful
for drugsthat are inactivatedthroughthispathway. Thisroute mayalsobe usedincaseswhere oral
administrationisprecluded(i.e.unconsciouspatient,vomitingpatient),butisdisadvantageousinas
much as itis inconvenientandthe absorptionisoftenirregularanddifficulttopredict.With
suppositories,the base orcarriermassivelyinfluencesthe degreeandrate of drug release.
Parenteral routesof administrationinvolve the use of ahollow needle todeliversolutionor
suspensionof drug,atvariousdepthsandlocationsof the body.Intravenousinjectionsare the most
commonlyusedparenteral administrationandwillinvolveinjectingtinyorlarge volumesof the drug
directlyintoavein,whichcanbe painful andinconvenient.Despite this,IV injectionsare the best
wayof administeringadrugfast (i.e.inemergency) whilstavoidingfirst-passmetabolism, and
produce predictable bloodplasmaconcentrationlevels.The preparationsare sterile andoften
include “waterforinjections”asthe solvent,perhapswithavasoconstrictorlikeadrenalinewhena
local and notsystemiceffectisrequired.Intramuscularandsubcutaneousinjectionsinvolve injecting
a volume of drugeitherdeepintoskeletal muscleorjustunderthe skinrespectively,producinga
slow reservoirof drugintothe body;the “depot” effect.
Topical deliveryinvolvesapplyingthe drugpercutaneously,whichisseldomusedforsystemic
circulationdue tobeingerraticandpoor, more oftenforlocal effect.Transdermal patchesfor
analgesiaandsmokingcessationexist,butmore commonlytopical applicationswillhave an
antiseptic,antifugal oranti-inflammatoryfunctionalongwithskinemollientsforprotective effects.

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Topical formulationslike ointments,pastesandcreamsinvolve the drugbeingcarriedinasemi-solid
base whichcan be hydrophobicorhydrophilicincharacter.Ointmentsare hydrophobicbecauseof
theiroilynature,creamsare semi-solidemulsionsandpastesare harderthanointmentsbecause of
a greatersolidmass.Ophthalmicpreparationsare alwayssterile,nasal dosage formsare always
solutionsof suspensionsandearformulationsare usuallyviscous toprolongthe contactwiththe
affectedareas.
Respiratoryadministrationprovidesanexcellentsurface forabsorption throughthe alveolar
epithelium,butthismeansthatparticle size playsanimportantrole inthe extenttowhicha drugis
absorbed.Drugparticleswithadiameterof 0.5 – 1 micronreach the alveolarsacs,anysmallerthan
thisand theyare exhaled;anylargerandtheyare depositedonthe bronchial airways.Thisroute of
administrationisuseful forthe directtreatmentof asthmaandothersuchillnesses,viapowdered
aerosolsormetereddose aerosolswithaliquefiedinertpropellant. Asaroute,thisisalso being
increasinglyrecognisedasa route of administeringbiotechnological therapeuticagentsfortargeted
delivery,likeproteinsandpeptides.
Drug Factors and Dosage Form Design
Many physical andchemical drugfactors require careful considerationbefore adrugwithproven
therapeuticbenefitbecomesalicensedmedicine foruse inthe publicdomain.These factorsinclude;
polymorphictendencies,aqueoussolubility,particle size,drug-excipientinteractionsandsolid-state
stability,whichcanall have huge differencesonthe physiological effectsof the druginthe body.
Properties Processingstresses Manufacturingprocedures
Particle size (surface area)
Particle surface chemistry
Solubility
Dissolution
Partitioncoefficient
Ionizationconstant
Crystal properties
Polymorphism
Stability
Organolepticnature
Molecularweight
Pressure
Mechanical
Radiation
Exposure toliquids
Exposure togassesand vapours
Temperature
Precipitation
Filtration
Emulsification
Milling
Drying
Mixing
Granulation
Compaction
Autoclaving
Crystallisation
Handling
Storage
Transport
The size of particlesisanaspectof preformulationstudiesthatisof massive importance,formany
reasons.Itis widelyrecognisedthatparticlesof asmallersize representalargerspecificsurface
(surface areaof drugparticles) thanlargerparticles,whichisseentoaidinthe dissolutionand
therefore solubilityof manydrugs.Fordrugslike griseofulvinandtolbutamideinwhichabsorption
involvesadissolutionrate-limitingstep,itisknownthatthe bioavailabilityof the drugmaybe
increased throughdecreasingthe particle size toincrease the specificsurface.Thisisbecause a
largersurface area resultsinfasterdissolutionof the drugandso will increase the rate of passive
diffusion.Nowadaysdue tothe fact that manynew drugsemerge withincrediblypooraqueous

5. George Wild Science of Medicines
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solubility,more novel methodsof improvingthispropertyare beingadopted,suchas;complexation
witha hydrophilicpolymer,co-precipitationwithadjuvantchemicalsandco-crystal formation.It
shouldbe notedthough,thatratesof dissolutioncanbe affectednegativelywhenexcipientsare
incorrectlyselected,despitethe factthatdrug particlesof a smallersize are used.Fine powderscan
actuallyincrease airabsorptionandagglomerationcomplications.Suspensions,inhalationaerosols
and topical formulationscanalsobe affectedwhenexcipientsare correctlyselectedbutthe particle
size iswrong,i.e.suspensionflowpropertiescanbe modified,topical preparationscanbe abrasive
and grittyand inhalationaerosolscanhave theiruptake acrossalveolar/bronchi mucosaimpaired.
Solubilityitself isanobviousfactortoconsiderinpreformulationthatcanand isoftenimproved
throughmodifyingthe saltorchemical derivatives,complexingwithanothercompound,micronizing
or usingsoliddispersiontechniques.Mostdrugsare acidicor basicand sothe extenttowhichthey
ionise willbe dependentuponthe pHat variouslocationsalongthe GI tract, whichinturn affects
theirsolubilityatthese sites.
The rate at whicha drugenterssolutionistermedasthe dissolutionrate andisoftenanimportant
stepthat mustbe overcome foranyand all drugsthat are not alreadyadministeredinsolutioni.e.
intravenoussolutionororal aqueoussolution.The rate itself isdeterminedbyanumberof factors
and can be illustratedthroughthe Noyes-Whitneyequation(below),wherekrepresentsthe intrinsic
dissolutionrate constant,A representsthe specificsurface,dm/dtrepresentsthe differenceinmass
dividedbythe difference in time andCS – C is the solubilityminusthe concentrationattime =t.
dm
dt
=kA(CS-C)
So,whena drug dissolvesparticleswill leave the bulkandenteradiffusionlayerarounditwhere the
concentrationisquite high.Fromhere,particleswilldiffuse outintosolutionandbe absorbed
throughvariousabsorbingmucosa,beingreplacedconstantlybyparticlesleavingthe bulk.If the
rate of dissolutionisquick,thenitfollowsthatthe rate-limitingstepof absorptionwill be dependent
on the abilityof the drugto meetwithandcross the variousbiological membranesatthe site of
action.
Drugs withintrinsicdissolutionrates(k) of below 0.1mg-1
cm-2
are expectedtoshow absorptionthat
isdissolutionrate-limited,because the valueof kischaracteristicand indeedindicative of manysolid
compounds,whenA andotherexperimental variablesare keptconstant. Thismeansthatdissolution
rate data,whenviewedinconjunctionwithpKadata,solubilitydataandpartitioncoefficientresults
can provide agood indicationof the invivoabsorptioncharacteristicsof the drug.However,invitro
testsare neededinassociationwiththesepredictionstoaccuratelyassessthe clinical implicationsof
the drug’sbehaviour.
The partitioncoefficientof drugsrepresentthe extenttowhicha drug will partitionacross
absorbable andunabsorbable fractions,whichisdependentuponlipophilicnature,hydrophilic
nature,degree of ionisationandparticle size.Whereasthe dissolutionrate isoftenthe limitingstep
indrugs that exhibitpooraqueoussolubility,foraqueousdrugsandthose withbettersolubilitiesit
will be the rate of absorptionthatdeterminesthe overallrate.Inthe firstinstance,physicochemical

6. George Wild Science of Medicines
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propertiesof the drugmay be modified,butthisislessapplicable whenitcomestomodifyingthe
absorption,whichismore dependentupon ioniccharacter;inthese instances,itwillbe molecular
modificationsthatare usedto improve the rate of absorption.Mostdrugs withsmall molecular
weightsare acidicor basicin nature and sowill be ioniseddependentuponpHinthe various
environmentsinthe GItract. Membranesinthe bodyare hydrophobicinnature andare more
permeable tolipophilicmoleculesthanhydrophilicones.Thisisbecause those moleculesthatare
lipophilicare unionisedandsodonot attract many watermolecule,causing asize increase.They
may therefore approachthe biological membranesandpassthroughwithoutbecomingboundor
repelledbythe variouschargesthatfeature onthe outside of the membrane.Onthe otherhand,
ionisedspecieswill eitherinteractwiththe membrane orbe toolarge to passthrough,resultingin
poor absorptionacrossthe membrane.Therefore,the overrulingfactorsaffectingabsorptionare;
the pH at the site of absorptionandthe lipophilicityof the unionisedspecies.
Usingthese ideasand the Henderson-Hasselbalchequationondrugionisation fractions,we can
buildthe pH partitionhypothesis thatfocussesonlipophiliccharacteraffectingabsorption.There
are flawsinthishypothesishowever,asthere are drugswithlow pH partitioncoefficientsand/or
whichare ionisedoverthe entire bodilypHrange thatstill exhibitgoodbioavailability;there MUST
therefore be otherfactorsinvolvedthatare notaccountedfor inthistheory.
The crystal propertiesof adrug mustalsobe considered, because inrealitymostdrugswill be
handledintheircrystalline formatsome pointduringtheirmanufacture.Crystalscanbe amorphous,
crystalline,anhydrous,hydrated(tovariousdegrees)orsolvatedif the solventisnotwater,andwill
exhibitdifferentcharacteristicswithregardtohardness,shape andsize.Some drugsmayalso
presentthemselvesinmore thanone crystal form, dependinguponsolventof crystallisation,
temperature of crystallisationandrate of cooling;these are saidtoexhibitpolymorphicactivity.
These differentpolymorphswill likelyhave differentphysicalpropertiessuchasrate of dissolution,
stabilityandmeltingpoint,whichwill undoubtedlyhave knock-oneffectsforthe therapeuticeffect
of the drug.It is notuncommon that lessstable (metastable) formsof adrug will revertnaturally
back to the more stable polymorphovertime orunderspecificconditions,whichcaneitherbe of
benefitorharm.Thisis because the more stable polymorphwilllikelyhave ahighermeltingpoint
due to a strongerand more stable lattice arrangement,whichmaycause the drug to precipitate
fromsolutionorsuspensionasreversionoccurs,whichhasobviousimplicationsforpatient
adherence anddrugsolubility.
Thistransitionbetweendifferentchemical formscanoccur inthe body,as withinsulinthe presence
of an acetate bufferandzinc.Here,aninsoluble complex formsof eitheramorphousorcrystalline
nature dependinguponpH.The amorphousformcontainsparticlesof 2micronsin size,whichare
quicklyabsorbedwithashortdurationof action,whereasthe crystallineformexhibitslargercrystals
10 – 40 micronsinsize that take longertoabsorb and therefore have alongerdurationof action.
These changesmayalsooccur duringmilling(i.e.digoxinandspironolactone),granulationanddrying
and othercompactionprocesses.Changesthatoccurduringthe lifetime of the medicine,suchasin
suspensions,maybe counteredbythe presence of additivesandsurface-active agents(surfactants).

7. George Wild Science of Medicines
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Chemical stabilityisperhapsone of the fundamental aspectsof medicinesbehaviourthatmustbe
consideredwhendesigningadosage form.Stabilitytestingprogrammesare usedtoassessdrug-
drug and drug-additive interactionsaswell astendencies toundergohydrolytic,oxidative,thermal
and light-relateddegradations.Esterslikeaspirincommonlyundergohydrolyticbreakdownif
exposedtomoisture orwaterandthe correct conditionsandvitaminslikeascorbicacidwill undergo
oxidative decomposition,whichmustbe consideredindevelopingadrugthat ischemicallystable
and therapeuticallyactive overthe maximumpossible range of conditions.Drugsensitivityto
breakdowncanbe classifiedaccordingtofourcategories:
- ONE: stable acrossall conditions,i.e.kaolin
- TWO: stable if handledcorrectly,i.e.aspirin
- THREE: moderatelystable,withspecial handling,i.e.vitamins
- FOUR: veryunstable,i.e.manyantibioticsinsolution
The mechanismsbywhichsome drugmoleculesbreakdownare oftencomplex tounderstand,but
thenan intricate understandingisnotactuallyrequiredinthe formulationof manydosage forms;
the problemscanbe overcome withthe simpleadditionof additivesand/orthe correctselectionof
packaging.Forexample,drugsthatare susceptible tohydrolyticbreakdownmayhave adesiccant
addedto them,be formulatedwithminimal moistureexposure (tolow moisture specifications) and
be packagedin moisture-freepacking. Otherdrugsthatsufferfromoxidative decompositioncanbe
formulatedwithantioxidants,andthose sensitive tolightcanbe placedamberglassbottlesor
appropriate tabletpackaging. Comparedtothe costsof developingandmodifyingthe physical,
chemical andmolecularpropertiesof the compound,packagingismuch, MUCH more economical.
Drugs insolutionshouldhave stabilitiesandeffectsthatare well understoodforthe pHrange 1 – 8
(i.e.the bodilypHrange),asstabilitycanoftenbe improvedsimplythroughthe additionof abuffer
to the solution.Preservativesmayalsobe neededforthose liquiddosage formsthatare particularly
susceptibletomicrobial contamination,suchasoral preparationsthatcontainsweetenersand
sugars.
It’salso importanttorememberthatstabilitymustbe consideredintermsof drug-druganddrug-
additive interaction,suchasbetweencolourants,flavours,flavourenhancers,preservatives,
viscositymodifiers,solvents,co-solvents,differentAPIs,emulsifiers,stabilisers,buffersandmore.
Nowadays,these interactionscanbe identifiedthroughmicrocalorimetryandDSC(differential
scanningcalorimetry).
Organolepticpropertiesmustalsobe consideredforpreparationsoftenadministeredorally,asit
requiredthatdrugsubstancesare acceptable tothe patient,asto increase the adherence.Flavours
are commonlyaddedtoovercome drugsthatare unpalatable,butthe drugmayalsobe placedina
capsule,microencapsulated,coatedorplacedinsuspensiondependingonvariousphysical and
chemical factorssuchas solubilityandpHeffects.The taste budsof the tongue respondquicklyto
bitterandsour tastes,whichcan be overcome throughthe additionof acitrus flavouring,butwater-
insolublederivativesof the drug(like amitriptyline palmoate) mayalsobe usedwhichhave little or
no taste.It isvital that the presence of flavoursormodificationof themmustnotinterferewiththe
bioavailability(andotherfactors) of the drug.

8. George Wild Science of Medicines
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The target populationissomethingthatmustbe thoughtof whenchoosinga flavouringaswell,as
paediatricmedicationsare likelytobe betteracceptedwhentheyare sweettastingandare
flavouredtomatchthe psychological connotationsof specificcolourings(i.e.lemontaste –yellow
colour).Diabeticpopulationswill notbe able totake medicineswhichhave ahighsucrose content
and so these preparationswill needtohave asweetenerlike sorbitol thatisnotbrokendowninto
glucose inthe body.Colourshelpstandardisecoloursof medicinesandcanbe natural like
carotenoids,syntheticlikeamaranth,aqueouslike amaranth,oil solublelike SudanIV,orinsoluble in
bothvehicles,like aluminiumlakes.Lakesare generallyaluminiumorcalciumcomplexesthatare
useful intabletcoatingsandtabletsbecause of theirimprovedlightstability.
Havingdiscussedsome of the drugfactors thatneedto be considered,it’salsoimportantto
rememberthatmattersof practicalityconcerningflowability,compactability,hygroscopicityand
othersuch elementsneedtobe consideredtoavoidlater,costlycomplicationsinformulation.Those
drugsthat are otherwise infallible buthave ahygroscopicnature canbe manufacturedin
environmentswithlowmoisture,thosewithpoorflow qualitiescanhave flow agentslike fumed
silicaadded,andthose thathave poor compactionpropertiescanbe identifiedreasonablyearlyon
(before large-scale manufacture)ininstrumentedtabletingmachines,duringpreformulation.
Therapeutic Considerations and Dosage Form Design
It’sall well andgoodif a drug physicallyworksandcanbe used,butit’salsonecessaryto consider
whathappensto a drug and itsuse indifferentscenarios.Dependingonthe patient’scondition,age,
weight,swallowingabilities,it maynotbe practical or evenpossibletoadministerone druginjust
one dosage form.Thisnecessitatesthe preparationof severaldifferentdosage formstomeetthe
needsof the clinicianaswell asforthe needsof certainsituations.It’salsotrue that differentdosage
formshave theirownadvantagesoverothers;some provide systemicbenefit,othersprovidelocal
effects,some drugsare requiredforimmediate effect,otherscanhave delayedorprolongedeffects
dependingonthe conditions.Thisversatilityhelpsformulationscientiststoproduce arange of
productsthat can be usedina varietyof importantclinical scenarios.
For example,asthmasuffererssufferingfromanasthmaattack will needemergency(immediate)
relief of the symptomsandsoinhalationaerosolshave beenformulatedtoprovide animmediate hit
of the drug to the affectedarea.Patientsrequiringimmediatereliefof anginapectoriswilltake
sublingual nitroglycerinsothatthe drugis rapidlyabsorbedintothe bloodstreamtorelieve the
patientof the painful andpotentiallydangerouseffectsof the condition.
The age of the patientisconsideredimportantbecause childrengenerallyshow betteradherence
withliquiddosage forms,due todifficultyswallowingsoliddosage forms, whereasolderpatientswill
prefersoliddosage formsbecause they’re generallymore practical.Liquiddosage formsbeing
administeredtochildrenalsocarriesthe advantage thatthe liquidcanbe dilutedtovaryingdegrees
to suitthe weightof the patienttowhichthe drug is tobe administered.
Targeteddrug deliverythroughthe use of liposomesandnanoparticlesisalsoacontentiousareaof
formulationsciencebecause of the benefitsof deliveringthe drugmainlytothe site where it was
originallyintended.Thishasparticularbenefitstopatientsreceivingdrugswithwidely-feltharmful

9. George Wild Science of Medicines
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effects,suchaspatientswithcancerreceivingcytotoxicchemotherapy. Alternative preparation
methodslike supercritical fluidprocessingwithCO2 asa solventand crystal engineeringtoprovide
specificcrystal propertiescanalsobe utilised.Withthe adventof gene therapy,formulation
scientistswillneedtouse these existingmethodsanddevelopmore novel approachestodrug
deliveryinordertodeliverlabile macromoleculestospecificphysiologicaltargets.Computational
pharmaceuticsisan emergingareaof thisfieldthatfocussesonthe use of in-silicoproceduresto
predictdrugproperties,experimental design,AI,neuralcomputingandoptimisationtoolsto
facilitate fasterandrational formulationdesign.