OINTMENTS, CREAMS, PASTE AND GELS.ppt

ointments creams pastes and jellies

1. UNIT 5

7. Ointmentsaresoftsemisolidpreparationsmeantforexternal
applicationtotheskinormucousmembrane.Theyusuallycontain
medicament,whichiseitherdissolvedorsuspendedinthebase.
Theyhaveemollientandprotectiveaction.
Characteristicsofanidealointment:
1.Itshouldbechemicallyandphysicallystable.
2.Itshouldbesmoothandfreefromgrittiness.
3.Itshouldmeltorsoftenatbodytemperatureandbeeasilyapplied.
4.Thebaseshouldbenon-irritantandshouldhavenotherapeutic
action.
5.Themedicamentshouldbefinelydividedanduniformly
distributedthroughoutthebase.

8. Accordingtotheirtherapeuticpropertiesbasedonpenetrationofskin.
(a)Epidermicointments
Theseointmentsareintendedtoproducetheiractiononthesurfaceof
theskinandproducelocaleffect.
Theyarenotabsorbed.
Theyactsasprotectives,antisepticsandparasiticides.
(b)Endodermicointments
Theseointmentsareintendedtoreleasethemedicamentsthat
penetrateintotheskin.Theyarepartiallyabsorbedandactsas
emollients,stimulantsandlocalirritants.
(c)Diadermicointments
Theseointmentsareintendedtoreleasethemedicamentsthatpass
throughtheskinandproducesystemiceffects.

9. Theointmentbaseisthatsubstanceorpartofanointment
preparationwhichservesascarrierorvehicleforthe
medicament.
Anidealointmentbaseshouldbeinert,stable,smooth,
compatiblewiththeskin,non-irritatingandshouldrelease
theincorporatedmedicamentsreadily.
Classificationofointmentbases:
1.Oleaginousbases
2.Absorptionbases
3.Water-removableoremulsionbases
4.Watersolublebases

10. Thesebasesconsistsofwaterinsolubleoilsandfats.Themost
importantaretheHydrocarbonsi.e.petrolatum,paraffinsand
mineraloils.Theanimalfatincludeslard.Thecombinationof
thesematerialscanproduceaproductofdesiredmelting
pointandviscosity.
(a)Petrolatum(Softparaffin)
Thisisapurifiedmixtureofsemi-solidhydrocarbons
obtainedfrompetroleum.
Yellowsoftparaffin(Petrolatum;Petroleumjelly)
Thisisapurifiedmixtureofsemisolidhydrocarbons
obtainedfrompetroleum.Itmaycontainsuitablestabilizers
like,antioxidantse.g.-tocopherol(VitaminE),butylated
hydroxytoluene(BHT)etc.
Meltingrange:38to56
0
C.

11. Whitesoftparaffin(Whitepetroleumjelly,White
petrolatum)
Thisapurifiedmixtureofsemisolidhydrocarbonsobtained
frompetroleum,andpreparedbybleachingyellowsoft
paraffin.Neverusedforopthalmicointmentsasitmay
causeirritationtoeye.
Meltingrange:38to56
0
C.
ThisbaseisusedinZincointmentB.P.C
b)Hardparaffin(Paraffin)
Thisisamixtureofsolidhydrocarbonsobtainedfrom
petrolatum.
Itiscolourlessorwhite,odorless,translucent,wax-like
substance.Itsolidifiesbetween50and57
0
Candisusedto
stiffenointmentbases.

12. ((c)Liquidparaffin(Liquidpetrolatum,Whitemineral
oil)
Itisamixtureofliquid,hydrocarbonsobtainedfrom
petroleumbydistllation.Itistransparent,colourless,
odourless,tastelessviscousliquid.
Onlongstorageitmayoxidizetoproduceperoxidesand
therefore,itmaycontaintocopherolorBHTas
antioxidants.
Itisinsoubleinwaterandalcoholandsolubleinetherand
chloroform.
Itisusedalongwithhardparaffinandsoftparaffintogeta
desiredconsistencyoftheointment.
Tubesforeye,rectalandnasalointmentshavenozzleswith
narroworificesthroughwhichitisdifficulttoexpelvery
viscousointmentswithouttheriskofburstingthetube.To
facilitatetheextrusionupto25%ofthebasemaybe
replacedbyliquidparaffins.

13. (i)Theyarenotabsorbedbytheskin.Theyremainon
thesurfaceasanocclusivelayerthatrestrictstheloss
ofmoisturehence,keepstheskinsoft.
(ii)Theyarestickyhenceensuresprolongedcontact
betweenskinandmedicament.
(iii)Theyarealmostinert.
(iv)Theycanwithstandheatsterilization,hence,sterile
ophthalmicointmentscanbepreparedwithit.
(v)Theyarereadilyavailableandcheap.

14. i)Itmayleadtowaterloggingfollowedbymacerationofthe
skinifappliedforaprolongedperiod.
(ii)Itretainsbodyheat,whichmayproduceanuncomfortable
feelingofwarmth.
(iii)Theyareimmisciblewithwater;asaresultrubbingonto
thesurfaceandremovalaftertreatmentbotharedifficult.
(iv)Theyaresticky,hencemakesapplicationunpleasantand
leadstocontaminationofclothes.
(v)Waterabsorptioncapacityisverylow,hence,thesebases
arepoorinabsorbingexudatefrommoistlesions.

15. Thesebasesaregenerallyanhydroussubstanceswhich
havethepropertyofabsorbing(emulsifying)
considerablequantityofwateryetretainingits
ointment-likeconsistency.
Theyarejustsimilartohydrocarbonbasesbuthaving
onedifferencethattheyarehydrophilicinnature.
Preparationsofthistypedonotcontainwaterasa
componentoftheirbasicformulabutifwateris
incorporatedaW/Oemulsionresults.

16. 1.WoolFat(anhydrouslanolin)
Itisthepurifiedfatlikesubstanceobtainedfromthewoolofsheep.
Itispracticallyinsolubleinwaterbutcanabsorbwaterupto50%of
itsownweight.Thereforeitisusedinointmentswherethe
proportionofwateroraqueousliquidstobeincorporatedin
hydrocarbonbaseistoolarge.
Duetoitsstickynatureitisnotusedalonebutisusedalongwith
otherbasesinthepreparationofanumberofointments.
e.g.SimpleointmentB.P.contains5%andtheB.P.eyeointment
basecontains10%woolfat.
2.HydrousWoolFat(Lanolin)
•Itisamixtureof70%w/wwoolfatand30%w/wpurifiedwater.It
isaw/oemulsion.Aqueousliquidscanbeemulsifiedwithit.
Itisusedaloneasanemollient.
Example:-HydrousWoolFatOintmentB.P.C.,CalamineCoalTar
Ointment.

17. 3.WoolAlcohol
Woolalcoholisobtainedfromwoolfatby
treatingitwithalkaliandseparatingthefraction
containingcholesterolandotheralcohols.It
containsnotlessthan30%ofcholesterol
Itisusedasanemulsifyingagentforthe
preparationofw/oemulsions.
Itisalsousedtoimprovethetexture,stability
andemollientpropertiesofo/wemulsions.

18. 4. Beeswax
It is purified wax, obtained from honey comb of bees.
It contains small amount of cholesterol. It is of two
types: (a) yellow beeswax and (b) white beeswax.
Use:-
Beeswax is used as a stiffening agent in ointment
preparations.
Examples:-Paraffin ointment B.P.C. contains beeswax.
5. Cholesterol
It is widely distributed in animal organisms. Wool fat
is also used as a source of cholesterol.
Use:-It is used to increase the water absorbing power of
an ointment base.

19. Advantagesofabsorptionbases:
(i)Theyarelessocclusivenevertheless,aregoodemollient.
(iiTheyassistoilsolublemedicamentstopenetratetheskin.
(iii)Theyareeasiertospread.
(iv)Theyarecompatiblewithmajorityofthemedicaments.
(v)Theyarerelativelyheatstable.
(vi)Theycanabsorbalargequantityofwateroraqueous
substances.
Disadvantages:Inspiteoftheirhydrophilicnature,
absorptionbasesaredifficulttowash.

20. W/OEmulsionBases
Lanolinandcoldcreamareexampleofw/oemulsionbases,used
asemollient.Theaqueousphasehydratestheskin.Oilyphase
formsanocclusivecoveringwhichpreventslossofwaterby
evaporation.MainDrawbackofw/oemulsionbaseistheir
greasyandsticknature.
O/WEmulsionBase
iHydrophlicointmentandvanishingcreamaretypeofo/w
emulsionbase.
iiEasilyremovedwithwater.
iiiTheyarenongreasyandnonsticky.
ivVanishingcreamareoftenusedascosmetic.

21. Watersolublebasescontainonlythewatersolubleingredientsandnotthefats
orothergreasysubstances,hence,theyareknownasgrease-lessbases.
Watersolublebasesconsistsofwatersolubleingredientssuchaspolyethylene
glycolpolymers(PEG)whicharepopularlyknownas“carbowaxes”and
commerciallyknownas“macrogols”.
Theyarearangeofcompoundswiththegeneralformula:
CH
2OH.(CH
2OCH
2)
nCH
2OH
ThePEGsaremixturesofpolycondensationproductsofethyleneandwater
andtheyaredescribedbynumbersrepresentingtheiraveragemolecular
weights.Liketheparaffinhydrocarbonstheyvaryinconsistencyfromviscous
liquidstowaxysolids.
Example:-
Macrogols200,300,400viscousliquids
Macrogols1500 greasysemi-solids
Macrogols1540,3000,4000,6000waxysolids.
DifferentPEGsaremixedtogetanointmentofdesiredconsistency.

22. AdvantagesofPEGsasointmentbase:
(a)Theyarewatersoluble;hence,veryeasilycanberemoved
fromtheskinandreadilymisciblewithtissueexudates.
(b)Helpsingoodabsorptionbytheskin.
(c)Goodsolventproperties.Some water-soluble
dermatologicaldrugs,suchassalicylicacid,sulfonamides,
sulfuretc.aresolubleinthisbases.
(d)Non-greasy.
(e)Theydonothydrolyze,rancidifyorsupportmicrobial
growth.
(f)Compatibilitywithmanydermatologicalmedicaments.

23. Disadvantages:
(a)Reductioninactivityofcertainantibacterial
agents,e.g.phenols,hydroxybenzoatesand
quaternarycompounds.
(b)Solventactiononpolyethyleneandbakelite
containersandclosures.
Certainothersubstanceswhichareusedaswater
solubleointmentbasesincludetragacanth,
gelatin,pectin,silicagel,sodiumalginate,cellulose
derivatives,etc

24. Awell-madeointmentis
(a)Uniformthroughouti.e.itcontainsnolumpsofseparatedhigh
meltingpointingredientsofthebase,thereisnotendencyforliquid
constituentstoseparateandinsolublepowdersareevenlydispersed.
(b)Freefromgrittiness,i.e.insolublepowdersarefinelysubdivided
andlargelumpsofparticlesareabsent.Methodsofpreparationmust
satisfythiscriteria.
Twomixingtechniquesarefrequentlyusedinmakingointments:
1.Fusion,inwhichingredientsaremeltedtogetherandstirredtoensure
homogeneity.
2.Trituration,inwhichfinely-subdividedinsolublemedicamentsare
evenlydistributedbygrindingwithasmallamountofthebaseorone
ofitsingredientsfollowedbydilutionwithgraduallyincreasing
amountsofthebase.

25. Whenanointmentbasecontainanumberofsolidingredientswithdifferent
meltingpointssuchaswhitebeeswax,cetylalcohol,stearylalcohol,stearic
acid,hardparaffin,etc.ascomponentsofthebase,itisrequiredtomeltthem.
Themeltingcanbedoneintwomethods:
Method-I
Thecomponentsaremeltedinthedecreasingorderoftheirmeltingpointi.e.
thehigherm.p.substanceshouldbemeltedfirst,thesubstanceswithnext
meltingpointandsoon.Themedicamentisaddedslowlyinthemelted
ingredientsandstirredthoroughlyuntilthemasscoolsdownand
homogeneousproductisformed.
Advantages:
Thiswillavoidover-heatingofsubstanceshavinglowmeltingpoint.
Method-II
Allthecomponentsaretakeninsubdividedstateandmeltedtogether.
Advantages:
ThemaximumtemperaturereachedislowerthanMethod-I,andlesstimewas
takenpossiblyduetothesolventactionofthelowermeltingpointsubstances
ontherestoftheingredients.

26. Thismethodisapplicablewhenthebaseissoftandmedicament
isinsolubleinbase.
(i)Solidsarefinelypowderedarepassedthroughasieve(#250,#
180,#125).
(ii)Thepowderistakenonanointment-slabandtrituratedwitha
smallamountofthebase.Asteelspatulawithlong,broadblade
isused.Tothisadditionalquantitiesofthebaseareincorporated
andtriturateduntilthemedicamentismixedwiththebase.
(iii)Finallyliquidingredientsareincorporated.Toavoidlossfrom
splashing,asmallvolumeofliquidispouredintoadepressionin
theointmentandthoroughlyincorporatedbeforemoreisadded
inthesameway.Splashingismoreeasilycontrolledinamortar
thanonatile.

27. Chemicalreactionswereinvolvedinthepreparationof
severalfamousointmentslikeiodineointmentwhichis
presenteitherinfreeorcombinedform.
(a)Ointmentcontainingfreeiodine
Iodineisonlyslightlysolubleinmostfatsandoils.
Iodineisreadilysolubleinconcentratedsolutionof
potassiumiodideinwaterduetotheformationof
molecularcomplexes(polyiodides)KI.I
2,KI.2I
2,KI.3I
2etc.
e.g.StrongIodineOintment(i)solventusedshouldbe
nonvolatileDuetoimproperstoragethewaterdriesup
andtheiodinecrystalsirritatetheskin,henceglycerolwas
sometimesaddedtodissolvetheiodine-potassiumiodide
complexinsteadofwater.

28. (b)Ointmentcontainingcombinediodine
Fixedoilsandmanyvegetableandanimalfatsabsorb
iodinewhichcombineswiththedoublebondsofthe
unsaturatedconstituents,andnofreeiodineislefte.g.
CH
3.(CH
2)
2.CH=CH.(CH
2)
7.COOH+I
2CH
3.(CH
2)
2.CHICHI.(CH
2)
7.COOHi.e.Oleicacidtodi-
iodostearicacid.
Theseointmentsaredark,greenishblackincolour.It
leavesnostainwhenrubbedintotheskin.
Hencetheyareknownasnonstainingiodine
ointment.

29. Anemulsionsystemcontainanoilphase,anaqueousphaseandan
emulsifyingagent.
Foro/wemulsionsystemsthefollowingemulsifyingagentsareused:
(i)watersolublesoap
(ii)cetylalcohol
(iii)glycerylmonostearate
(iv)combinationofemulsifiers:triethanolaminestearate+cetylalcohol
(Forw/oemulsioncreamsthefollowingemulsifiersareused:
(i)polyvalentionse.gmagnesium,calciumandaluminiumareused.
(ii)combinationofemulsifiers:beeswax+divalentcalciumion

30. Procedure:
(i)Water immiscible components e.g. oils, fats,
waxes are melted together over water bath (70
0
C).
(ii)Aqueous solution of all heat stable, water soluble
components are heated (70
0
C).
(iii) Aqueous solution is slowly added to the melted
bases with continuous stirring until the product cools
down and a semi-solid mass is obtained.
N.B. The aqueous phase is heated otherwise high
melting point fats and waxes will immediately solidify
on addition of cold aqueous solution

31. Theseareviscoussemisolidemulsionswhichare
meantforexternaluse.Theyusuallycontainawater
solublebaseduetowhichtheycanbeeasilyremoved
fromtheskin.
Theyareofsofterconsistencyandhavelightweightin
comparisontotrueointments.
whenappliedtotheskincreamsleavenovisible
evidenceoftheirpresenceonskin.

32. 1.Aqueouscreams:theseemulsionsareoilinwater
type.Thesecreamsarerelativelynongreasyandare
offurther3typesdependinguponthetypeof
emulsifyingagentused:
i.Anionicemulsifyingwaxcreams-emulsifying
ointment.
ii.Cationicemulsifyingwaxcreams–prepared
usingcetostearylalcoholandcetrimide
iii.Non-ionicemulsifyingwaxcreams-prepared
usingselfemulsifyingsorbitanester,macrogol
esters,polysorbates,PVAetc.

33. MethodofPreparation:
Thesecreamsarepreparedbyfusionmethod.Thewax
andoilyingredientsaremeltedtogetherandcooledto
about60
0
c.Thewateroraqueoussolutioniswarmedto
thesametemperatureandmixedwiththeoilymixture
withcontinuousstirring,continueduntilcold.

34. 2.Oilycreams:theseemulsionsarewaterinoiltype.
Thesecreamsarerelativelygreasyandareoffurther2
typesdependinguponthetypeofemulsifyingagent
used:
i.Sterolcreams:thesecreamsarew/otypeemulsions
inwhichwoolfatorwoolalcoholisusedas
emulsifyingagent.
ii.Soapcreams:thesearewaterinoilemulsionsin
whichtheemulsifyingagentsusedare
triethanolaminesoap,calciumsoaporboraxsoap

35. Thesecreamsarepreparedbyfusionmethod.Thewax
andoilyingredientsaremeltedtogetherandcooledto
about70
0
c.Thewateroraqueoussolutioniswarmed
tothesametemperature(70
0
c)andaqueousphaseis
mixedwiththeoilymixturewithcontinuousstirring,
continueduntilcold.

36. Thewidemouthedjarsareusedforstorageofcreams
wheretheriskofcontaminationinuseisconsideredto
beminimum.
Containersmustbewellclosedtopreventevaporation
ofwater.
Mouthofthejarshouldbecoveredwithadiscof
greaseproofpaper.
Collapsibletubesaretobepreferredtostorecreams
whichreducesthechancesofcontamination

37. Secondarylabel“FOREXTERNALUSEONLY”and
“STOREINACOOLPLACE”.
Thecreamsshouldbestoredinacoolplaceand
shouldbeprotectedfromhighertemperatureordirect
sunlight.

38. Pastesaresemisolidpreparationsintendedforexternal
applicationtotheskin.
Thesearegenerallyverythickandstiff.
Theydonotmeltatordinarytemperatureandthus
formsaprotectivecoatingovertheareawheretheyare
applied.
Theyaremainlyusedasantiseptic,protectiveor
soothingdressingswhichareoftenspreadonlint
beforebeingapplied.

39. 1.Hydrocarbonbases:softparaffinandliquid
paraffinarecommonlyusedbases.
2.Watermisciblebases:emulsifyingointmentand
glycerineisusedasawatermisciblebasesforthe
preparationofpaste.
3.Watersolublebases:suitablecombinationofhigh
andlowmolecularweightpolyethyleneglycolsare
mixedtogethertogetproductofdesiredconsistency
whichsoftenormeltwhenappliedtotheskin

40. 1.Fusion method: It is used when the base is liquid or
semi solid.
2.Trituration method: It is used when the base is
semi solid or solid.

41. Gelsaretransparentortranslucent,nongreasy,
semisolidpreparationgenerallyappliedexternally.
Theyareusedformedication,lubricationandsome
miscellaneousapplications.
Theymaybepreparedfromnaturalgumssuchas
tragacanth,pectin,sodiumaliginateorfromsynthetic
derivativesofnaturalsubstancessuchasmethyl
celluloseandsodiumCMC.
Thesearesimilartomucilageaspreparedfromgums
butdifferinhavingjellylikeconsistency.

42. Medicated Jellies
Lubricated Jellies
Miscellaneous Jellies
a.For patch testing
b.For electro cardiography

43. Thesearechieflyusedonmucousmembrane.Water
solubledrugslikelocalanesthetics,spermicidesand
antisepticsaresuitableforincorporationinthegels.They
areeasytoapplyandevaporationofthewatercontent
producesapleasantcoolingeffect.Themedicinalfilm
usuallyadhereswellandgivesprotectionbutiseasily
removedbywashingwhenthetreatmentiscomplete
e.g.Ephedrinesulfatejelly-usedtoarrestbleedingfrom
nose.
PramoxineHCl,alocalanesthetic-relievesdiscomfortof
pruritisandhemorrhoids.
Phenylmercuricnitrate–asspermicidalcontraceptive.

44. Catheters,itemsofeletrodiagnosticequipment,such
ascystscopes,andrubberglovesorfingerstallsused
forrectalandotherexaminationsrequirelubrication
beforeuse.
Thelubricantsmustbesterileforarticlesinsertedinto
sterileregionsofthebody,suchasurinarybladder.For
painfulinvestigationsalocalanaestheticmaybe
includedasinLignocaine.

45. PatchTesting:
Controlledapplicationofbiologicalorchemicalsubstancestotheskininorder
todetectifthesubjecthasanallergichypersensitivitytooneofthem.Thetest
wasoriginallydevelopedtotestnewchemicalcompoundsfortheirallergic
potentialonanimalsbuthassincebecomewidelyusedtodiagnoseallergiesin
humans.Patchtestingisusuallydoneontheskinoftheupperbackortheouter
arm.Smallamountsoftestsubstancesdilutedinasolventsuchaswater
orpetroleumjellyareappliedtotheskinunderapatchofclothorsoftpaper
andanimpermeablemembrane.Thepatchisleftinplacefor48hours,after
whichtheskinreactionisexaminedandscoredfrom0(noapparentreaction)
to4+,indicatingsevereblisteringaswellasangryrednessoftheexposedsk
Electrocardiography:
Toreduceelectricalresistancebetweenthepatient’sskinandelectrodesofthe
cardiograph,anelectrodejellymaybeapplied.ThiscontainsNaCltoprovide
goodconductivityandoftenpumicepowderwhichwhenappliedontotheskin,
removespartofthehornylayeroftheepidermis,themainlayerofelectrical
resistance

46. Pharmaceuticalgelsareusuallypreparedbyaddinga
thickeningagentsuchastragacanthorcarboxy
methylcellulose(CMC)toanaqueoussolutionin
whichdrughasbeendissolved.Themassistriturated
inamortaruntilauniformproductisobtained.
Forthepreparationofgelswholegumispreferred
ratherthanpowderedgumbecausetheformergivesa
clearpreparationofuniformconsistency.
Thefollowinggellingagentsareusedforthe
preparationofgel

47. Themainhydrophiliccomponentoftragacanththatgelsinwaterhas
beennamedbassorin-hence,tragacanthjelliesaresometimescalled
bassorinpaste.
Theamountofgumrequiredforapreparationvarieswithitsuse:
Forlubricatingjelly2to3%.
Fordermatologicalvehiclesabout5%.
Forincorporationofichthamol,resorcinol,salicylicacidandother
medicaments,about5%isgenerallyused.Allformulationscontain
alcoholand/orglyceroland/oravolatileoiltodispersethegumand
preventlumpinesswhenwaterisadded.
Theyvaryinviscosity,duetothenaturaloriginofthegumand
variationsinmillingandstorage.
Thefilmleftontheskintendstoflake.
ViscosityisrapidlylostoutsidethepHrangeof4.5to7.0.
Theyaresusceptibletomicrobialgrowth

48. Aslubricant-1.5to2%isused.
Asdermatologicalvehicle-5to10%isused.
AtraceofCa-salt(CaCl
2)maybeaddedtoincrease
theviscosityandmostformulationscontainglycerolas
adispersingagent.
Advantage:Sodiumalginatehasanadvantageover
tragacanththatisavailableinseveralgradeor
standardizedviscosity.

49. Pectinisaverygoodgellingagentandisusedinthe
preparationofmanytypesofgelsincludingediblegels.
Glycerinisusedasadispersingagentandhumectants
indermatologicalgels.
Gelsmustbepackedinwell-closedcontainersbecause
theylosewaterrapidlybyevaporationandthisis
increasedbythesusceptibilityofpectingelsto
syneresis(i.e.exudationoftheaqueousphaseasa
resultofcontractionofthegel).

50. Starchmucilagepreparedalonewithwaterleadto
bacterialgrowth,soasuitablepreservativeisadded.
Starchincombinationwithgelatinandglycerinis
commonlyusedforpreparationsofgels.
Glycerinin50%mayactaspreservative.
Medicamentsareincorporatedinthecoldgelby
trituration.

51. •Insolubleincoldwaterbutswellandsoftensinit.Itis
solubleinhotwater.
•Hotsolutioncontaining2%gelatinformsajellyon
cooling.
Verystiff(15%)gelsaremeltedbeforeusedandafter
coolingtodesiredtemperatureareappliedwitha
brushtotheaffectedarea.

52. Methylcelluloseandsodiumcarboxymethylcellulose
produceneutralgelsofstableviscosity.
Havegoodresistanceagainstmicrobialgrowth.Clear
duetofreedomfrominsolubleimpurities.Produce
strongfilmafterdryingontheskin.
NaCMCisusedtopreparejelliesforlubricationas
wellassterilejellies.

53. Gels containing 7 to 20 % of bentonite can be used as
dermatological bases

54. Thesearepreparedbyaddingathickeningagentsuch
astragacanth,carboxymethylcelluloseetctoan
aqueoussolutionofdrug.Themassistrituratedin
mortaruntilauniformproductisobtained.
Theglasspestleandmortarisusedincaseofdark
coloureddrug.
Thewholegumshouldbepreferredoverthepowdered
gumasitformsaclearpreparationofuniform
consistency.

55. •Althoughsomebaseslikeclaysandcellulosederivative(s)
resistmicrobialcontaminationbutsinceallthejellies
containlargeamountofwater,thereforemustbesuitably
preserved.e.g.Methylparaben0.1to0.2%iscommonly
used.
Lossofwatercanquicklyleadtoskinformationonjellies
andtopreventthehygroscopicsubstances,e.g.glycerol,
propyleneglycolorsorbitolsolutionmaybeadded.
•Basesandmedicamentssensitivetoheavymetalsare
sometimesprotectedbyachelatingagente.g.(EDTA)

56. EVALUATION OF SEMISOLID DOSAGE
FORMS

65. THANK YOU