Gastrointestinal Agents

GIT Agents

1. Gastrointestinal Agents

2. Acidifiers
-Ammonium chloride*
-Dilute HCl
Antacid
-Ideal properties of antacids
-Combinations of antacids
-SodiumBicarbonate
-Aluminum hydroxide gel
-Magnesium hydroxide mixture

3. •Cathartics
-Magnesium sulphate
-Sodium orthophosphate
-Kaolin
-Bentonite

4. •Antimicrobials
-Mechanism
-Classification
-Potassium permanganate
-Boric acid
-Hydrogen peroxide
-Chlorinated lime
-Iodine and its preparations

5. Acidifying agents or acidifiers
❖Thesearethedrugswhichareabletoincreasethe
acidityinGIT.Someofthesedrugsareusedtoincrease
metabolicacidosiswhereassomeoftheseareusedto
increasethegastrichydrochloricacid.
❖AmmoniumchlorideUSP,sodiumphosphateUSPand
CalciumChlorideUSPareemployedassystemic
acidifiers.

6. 1.Gastricacidifiers:Thesearedrugswhichareusedto
restoretemporarilytheacidityofthestomachin
patientssufferingfromachlorhydriaand
hypochlorhydria.E.g.diluteHCl.
2.Urinary acidifiers:These are the drugs which are
used to render acidic urine to enable treatment of
some types of urinary tract disorders.

7. 3.Systemicacidifiers:Thesearethedrugswhichare
abletoneutralizethealkalinebodyfluidsparticularly
bloodinpatientswhoaresufferingfromsystemic
alkalosis.
4.Acids:theseareusedaspharmaceuticalsaidsinthe
preparation,laboratoryqualitycontrol,etc.

8. DiluteHydrochloricacid
Preparation
•Itispreparedbyadding274gofconcentratedHCl
slowlyinto726gofpurifiedwater.
•Pungentodor
•Fuming
•Itreactwithmetalsandreleaseshydrogengas.

9. Assay
•Acidimetry-alkalimetry
•Substancedissolvedinwaterandtitratedagainst
sodiumhydroxideusingmethylredasindicator.
•Neutralizationreactiontakesplace.
•Methylredindicatorisyellowinalkalimediumandit
changestoredinacidmedium

10. Ammonium Chloride
Preparation
Commercial
• Neutralization of Ammonia with HCl yields Ammonium
chloride.
• The purification is done by sublimation from iron pan.

11. By heating ammonium sulphate with sodium chloride

12. Assay
Substancedissolvedinwaterandtoitpreviously
neutralizedformaldehydeisadded.
•Reason:Formaldehydemayhavesmallamountof
formicacid,whichmustbe
neutralizedbeforethesodiumhydroxideusing
phenolphthalein.
•TitratedagainstSodiumhydroxideusing
phenolphthaleinasanindicator

13. •Endpointistheappearanceofpalepermanentpink
color.
•Inthisammoniumchlorideundergoeshydrolysisand
yieldammoniumhydroxideandHCl.
•Thisreactionisfaciliatedbyformaldehydebyfixing
ammoniaashexamine.
•Theacidformedistitratedagainstsodiumhydroxide.
•Indicatoriscolorlessinacidandpinkinalkaline
medium.

15. Uses
•0.8%w/vsolutionisisotonicwithserum.
•Systemicacidifier
•Diuretic
•Expectorant
•Diaphoretic
•Itincreasesthelocalirritationwhichleadstoincrease
therespiratorytractsecretionsandmakestheless
viscousmucus.Soammoniumchlorideandcarbonate
areusedincoughpreparation.

16. Antacids
❖Thesearethedrugswhichareusuallyalkaline
substancesandusedforneutralizingexcessacidin
thestomachofpatientssufferingfromhyper-
chlorhydria(hyperacidity).Antacidsgive
symptomaticrelieffrompainbyneutralizingthe
excessofHCl.
❖Thusantacidsfinduseinthetreatmentofulcersby
reducingpain.Antacidsactongastrointestinaltract
afterbeingconvertedintosolublesaltsbyHCl.

17. ❖Thecationssuchascalcium,aluminum,etcare
havingconstipatingeffectwhereasthatof
magnesiumishavinglaxativeeffect.
❖Therefore,combinationsofcalcium-magnesiumor
aluminum-magnesium saltsaregenerally
employedasantacids.

18. Ideal requirements of an antacid are as
follows:
1.Itshouldbeinsolubleinwaterandhasfineparticle
form.
2.Itshouldnotbeabsorbableorcausesystemic
alkalosis.
3.Itshouldbeabletoexertitseffectgraduallyand
overalongperiodoftime.
4.Itshouldnotbealaxativeorcauseconstipation.

19. 5.Itshouldnotcauseanysideeffects.
6.Itshouldbestableandreadilyavailable.
7.ThereactionbetweenantacidandgastricHCl
shouldnotproducelargevolumeofgas.
8.TheantacidshouldbufferinthepHrange4to6.

20. 9.Theantacidshouldprobablyinhibitpepsin,the
proteolyticenzyme.
❖Althoughnocompoundorpreparationisconsidered
tobeidealfortheabovecriteriayetsome
compoundslikealuminum,calciumandmagnesium
arewidelyused.

21. Aluminiumcompoundsasantacids
❖Aluminiumcompoundsformoneofthemostwidely
usedclassesofantacids.Amongaluminium
compound,Al(OH)
3iswidelyused.
AluminiumHydroxide Gel
❖Itisanaqueouswhiteviscoussuspensionofhydrated
aluminiumoxidehavingvaryingamountsofbasic
aluminiumcarbonate.Thepreparationcontainsnot
lessthan3.5%andnotmorethan4.4%w/wof
aluminiumoxide(Al
3O
3).

22. Preparation
❖Itispreparebyaddingahotsolutionofpotashalum
slowlywithconstantstirringtoahotsolutionof
sodiumcarbonate.Aftercompleteremovalofcarbon
dioxidetheprecipitatedaluminiumhydroxideis
filtered.
❖Itiswashedthoroughlywithhotwateruntilit
becomesfreefromsulphateion.Theprecipitateis
suspendedindistillwatertotherequiredstrength.
3Na
2
CO
3
+ 2KAl (SO
4
)
2
+ 3H
2
O 3Na
2
SO
4
+ 2Al (OH)
3
+ 3CO
2

23. Assay
➢Weighed5gofsubstanceisaccuratelyweighedand
takeninaflaskandadd3mlofHCl.
➢Thesolutioniswarmedonwaterbath,coolingand
transferredtoa100mlvolumetricflaskandmake
100mlwithdistilwater.
➢Now20mlofthesolutionistakenfromthe
volumetricflaskintoconicalflaskandadd40ml
0.05MdisodiumEDTAfollowedby80mlofwater
andafewdropsofmethylredsolution.

24. ➢Tothis1NNaOHsolutionisaddedtoneutralizethis
solutionbychangeofcolorfromredtoyellow.
➢Nowtheflaskiswarmedonawaterbathforabout
30minutesandthenadded3ghexamineandfew
dropsofxylenolorangesolutionasanindicator.
➢Theadditionof0.05Mleadnitratesolutionuntil
violetcolorisappearsattheendpointdueto
formationofleadxylenolorangecomplex.

25. Uses
Itisaveryeffectiveslow-actingantacid.Al (OH)3 + 3HCl AlCl3 + 3H2O
Aluminumhydroxideisrecognizedbythetwophysical
forms.
1.Aluminumhydroxidegel:itisawhiteviscous
suspension,fromwhichsmallamountsofclearliquid
mayseparateonstanding.IthaspHbetween5.5to
8.0.

26. 2.Driedaluminumhydroxidegel:itisnotatypical
gelbutisawhite,odorless,tasteless,amorphous
powderinsolubleinwaterandalcoholbutsolublein
dilutemineralacidsandsolutionsoffixedalkali
hydroxides.

27. ➢Boththegelanddriedgelarepopularantacids.
➢Theypossessmanyofthepropertiessoughtinthe
idealantacidalthoughtheironsetofactionis
slower.
➢Aproblemwiththegelsisthatofalossantacid
propertiesonaging.
➢Thisismoreofaproblemwiththedriedgelthan
withtheliquidsuspensionandseemstoberelated
tothemanufacturingprocess

28. Calcium compounds as antacids
❖Calciumcarbonateandcalciumphosphateis
widelyusedasantacids.
Calcium carbonate
Formula:CaCO
3
Mol. Wt:100.09
Synonym:precipitated Chalk

29. Preparation
❖Thecompoundisobtainedbymixingtheboiling
solutionsofcalciumchlorideandsodiumcarbonate
togeneratecalciumcarbonateprecipitation.
❖Theprecipitateiscollectedonfilterandwashed
withboilingwateruntilitbecomesfreefrom
chlorideionsandfinallyprecipitateisdried.
CaCl
2+Na
2CO
3 CaCO
3+2NaCl

30. Assay
❖Itmaybeassayedbycomplexometricmethod.1gof
accuratelyweighedsamplesufficientlymoistened
withwaterandsufficientlyHClisaddedtogetaclear
solution.Addingamorewaterandvolumeismade
up250ml.take5omlofthissolution
❖adjustpHwithfreshlyprepared1NNaOHsolution.
Thenadd40mgofmurexideand3mlsolutionof
naphtholgreenandtitratedwith0.05MEDTA
solutionuntiladeepbluecolourisobtained.

31. Uses
❖Theprecipitatedchalkusedasdentifrice.Itis
rapidlyactingnon-systemicantacid.Itneutralizes
gastricacidandformscalciumchloride.
❖Thelatterisconvertedinintestinetoaninsoluble
calciumsaltwhichtendstobeconstipating.Hence,
calciumandmagnesiumantacidsareusuallygiven
incombination.
CaCO
3+HCl CaCl
2+CO
2+H
2O

32. Milk of Magnesia
Formula: Mg (OH)
2
Mol.wt: 58.32
Itisasuspensionhavingnotlessthan7%w/wandnot
morethan8.5%w/wofMg(OH)
2inpurifiedwater.

33. Preparation
❖Itispreparedbyeitherreactionbetweensolutionof
NaOHandMgSO
4orsolutionofNaOHandMgO.
❖Theprecipitatedissettlingdownandfiltersit.The
residueiswashedwithwateruntilitbecomesfree
fromsulphateions.
❖Ifthepreparationisdonefrommagnesiumsulphate
andsodiumhydroxide,thentheprecipitateof
Mg(OH)
2isgelatinoustranslucentsuspension.

34. ❖Ifmagnesiumoxideisused,thesuspensionappears
whiteandofacreamyconsistency.
MgO+H
2O Mg(OH)
2
MgSO
4+2NaOH Mg(OH)
2+Na
2SO
4

35. ❖Pharmacopoeiaallowstheuseof0.1%citricacidsoas
tominimizetheactionoftheglasscontainerofmilkof
magnesia.Theadditionof0.2%ofmethylparabenor
0.125%ofsodiumbenzoateisalsousedasa
preservativeinthepreparation.
❖Themilkofmagnesiaisusuallydispersedinblue
colouredbottles.Becauseitenhanceswhitenessand
makestheappearanceofpreparationmorepleasing.

36. Assay
❖Anaccuratelyweighedsample(5ml)is
takeninaflask.Add25mlof1NH
2SO
4is
added.Nowexcessofacidisbacktitrated
with1NNaOHusingmethylredasan
indicator.
Uses
❖Itisusedasantacidandlaxative.
Mg(OH)
2+ 2HCl MgCl
2+ 2H
2O

37. Sodium bicarbonate
Formula:NaHCO
3
Mol.wt:84.01
Synonym:Baking soda
Preparation
Onasmallscale,itispreparedbypassingCO
2gas
throughasolutionofsodiumhydroxide.Thesolution
isconcentratedtogettheproduct.
NaOH + CO
2 Na
2CO
3 + H
2O
Na
2CO
3+ H
2O + CO
2 NaHCO
3

38. ❖Onindustrialscale,itisobtainedbytheSolvay
process.Brinesolution(NaCl)issaturatedwith
ammoniatoremovetracesofimpuritieslikeMg
andFe.Thesolutionisfilteredandpassedthrough
thecarbonatingtower.Inthisitisallowedtocome
incontactwithacurrentofCO
2andtoweris
cooledtoenhanceprecipitation.Theprecipitateis
filteredanddried.
H
2O + CO
2 H
2CO
3
NH
3+ H
2CO
3 NH
4HCO
3
NaCl + NH
4HCO
3 NaHCO
3+ NH
4Cl

39. Assay
1gsampleisweighedaccuratelyanddissolved20ml
ofwater.Itistitratedwith0.5NH
2SO
4usingmethyl
orangeasanindicator.
Uses
Inmedicine,compoundisusedasantacid.Itisalso
usedforpreparingbuffersolutions.
NaHCO
3+ HCl NaCl + H
2O + CO
2

40. HyperchlorhydriaHypochlorhydria
DefinitionHyperchlorhydria
refers to the state in
the stomach where
gastric acid levels are
higher than the
normal range.
Achlorhydria or
hypochlorhydria refers to
states where the
production of gastric acid
in the stomach is absent
or low, respectively.

41. CausesIncorrect & irregular
eating habits,
Smoking, tobacco
chewing, spicy foods
and some medicine
cause acidity
carcinoma of the
stomach, chronic
nephritis, chronic
alcoholism,
hyperthyroidism,
tuberculosis, pellagra,
parasitic infections

42. SymptomsUncomfortable feeling of
overeating, a growing
hungry feeling between
meals, heartburn,
stomach pain,
hemorrhage
Mild diarrhea,
frequent bowel
movements,
epigastric pain and
sensitivity to spicy
foods
TreatmentUsing antacids compounds
such as NaHCO
3, Mg(OH)
2,
Ca(OH)
2, Al(OH)
3etc.
Using Acidifying
agents such as NH
4Cl,
CaCl
2etc.

43. ➢Antacidsgivesymptomaticrelieffrompainby
neutralizingtheexcessofHCl.Thusantacidsfinduse
inthetreatmentofulcersbyreducingpain.Antacids
actongastrointestinaltractafterbeingconverted
intosolublesaltsbyHCl.
➢Thecationssuchascalcium,aluminum,etcare
havingconstipatingeffectwhereasthatof
magnesiumishavinglaxativeeffect.Therefore,
combinationsofcalcium-magnesiumoraluminum-
magnesiumsaltsaregenerallyemployedasantacids.

44. LAXATIVE, CATHARTICS AND PURGATIVES
❖Catharticsmaybedefinedassubstanceswhich
bringaboutdefecation.Theyarebeneficialin
constipationandforexpulsionofintestinalparasites.
Theymayalsobegivenforclearingbowelsbefore
surgery.
❖Purgativesareactsimilarlytocatharticsbutthey
aremildinnatureofaction.Purgativesactsimilarly
tocatharticsbutaremildinnatureofaction.
❖Laxativesactsimilarlybutaremildtypeof
purgatives.Hence,theygivetosameeffectbutvaryin
natureandinmechanism.

45. Catharticsorpurgativesorlaxativesareactby
fourdifferentmechanisms
1.Stimulants:Thesearethedrugsorchemicals
whichactbylocalirritationonintestinaltractand
bringaboutstimulationofperistalticactivity.Ifthey
actdirectlyonintestineandstimulateperistalsis,they
aretermedasstimulants.E.g.senna,rhubarb,
podophyllum,castoroil,aloe,bisacodyletc.

46. 2.Bulkpurgatives:Thesearetheagentswhichareableto
increasebulkofintestinalcontents.Thesearecelluloseor
non-digestibletypesofmaterialswhichswellconsiderably
whenwetandbecauseofincreasedbulkstimulate
peristalsis.
3.Lubricants:Inconstipation,contentsofintestine
becomehardbecauseofabsorptionofwaterbybodythere
resultsdifficultyinclearingofbowels.Substancesuchas
liquidparaffin,glycerin,mineraloilsetc.actaslubricants
andcausesmoothclearanceofthefecalmaterial.

47. 4.Salinecathartics:Theseactbyincreasingthe
osmoticloadofintestinebyabsorbinglargequantityof
waterandtherebystimulateperistalsis.Thesaline
catharticsarewatersolublemainlyinorganic
chemicalsandtheyaretakenwithplentyofwater.This
ishelpfulinrestrictingexcessivelossofbodyfluidand
reducesnauseaandvomiting.

48. Magnesium sulphate
Formula: MgSO
4
Mol.wt: 246.5
Synonym: Epsom salt
Preparation
ItisobtainedbytheactionofdiluteH
2SO
4on
magnesiumcarbonateormagnesiumoxideorfrom
nativecarbonate.
MgCO
3+ H
2SO
4 MgSO
4+ H
2O + CO
2

49. Assay
0.3gsampleisdissolvedin50mlofwaterandadded
10mlammonia-ammoniachloridesolutionthen
titratedwith0.05Mdisodiumethylenediaminetetra
acetateusing0.1gofMordantBlack11mixtureas
indictoruntilthepinkcolourchangedtoblue.

50. Uses
Itisusedassalinecathartics.MgSO
4isnotabsorbed
fromintestinaltractandthusretainssufficientwater
withlumen.Thehydrostaticpressureisableto
promotemotoractivityorperistalsisofbowel.Itis
alsousedinpatientswithimpairedrenalfunction.

51. Sodium orthophosphate
Mol. Formula: NaH2PO4
Properties
1. Dry Powder, Pellets Large Crystals, Wet Solid
2. Colorless
3. Solubility-14.5 g/100 g water at 25 deg C
4. Density-2.54 g/cu cm
5. Decomposition-75°C
6. pH-11
7. Molecular Weight-163.939 g/mol

52. Assay
Dissolveanaccuratelyweighedquantityofthe
sample,equivalenttobetween5.5and6gofanhydrous
Na3PO4,in40mlofwaterina400-mlbeaker,andadd
100mlof1Nhydrochloricacid.
Passastreamofcarbondioxide-freeair,infine
bubbles,throughthesolutionfor30mintoexpel
carbondioxide,coveringthebeakerlooselytoprevent
lossbyspraying.

53. Washthecoverandsidesofthebeakerwithafewml
ofwater,andplacetheelectrodesofasuitablepH
meterinthesolution.
Titratethesolutionwith1Nsodiumhydroxidetothe
inflectionpointoccurringataboutpH4,
thencalculatethevolume(A)of1Nhydrochloric
acidconsumed.Protectthesolutionfromabsorbing
carbondioxidefromtheair,andcontinuethetitration
with1Nsodiumhydroxideuntiltheinflectionpoint
occurringataboutpH8.8isreached.

54. Calculatethevolume(B)of1Nsodiumhydroxide
consumedinthetitration.When(A)isequalto,
greaterthan,2(B),eachmlofthevolume(B)of1N
sodiumhydroxideisequivalentto163.9mgof
Na3PO4.When(A)islessthan2(B),eachmlofthe
volume(A)-(B)of1Nsodiumhydroxideis
equivalentto163.9mgofNa3PO4.

55. LightKaolin,IP
Preparation:Itdiffersfromtheheavyvarietymainly
inthedegreeofpurityandinparticlesize.Itis
preparedfromheavykaolinbyelutriation,Reducing
grittyandcoarseparticles.Itshouldnotcontainany
dispersingagent.Properties:Itisalightwhite
powder,unctuous(Ointmentlike,soft)totouch.

56. Uses:
Usedincathartics.
Lightkaolinismainlyusedasadsorbentfortoxic
substancesfromthegastro-intestinaltractandto
providebulkbyswellingwithwaterinconditionsof
diarrhoea.Itmayalsobeusedinpoultices.dusting
powders,toiletpowdersandasfilteringaid.

57. HeavyKaolinIP
Occurrence:Thisisapurifiedformofanaturalclay
havinganapproximatecompositionAl2O3.
2SiO2.2H2O.Naturalkaoliniscontaminatedwith
carbonatesofcalciumandmagnesiumandferric
oxide.Thesecanbeeasilyremovedbytreatment
withhydrochloricacid,followedbyfiltration,
washinganddrying

58. Properties:Itisasoftwhitishpowder,odorlessand
almosttasteless.Itisinsolubleinwater,organic
solvents,mineralacidsandalkalisolutions.
Uses:-Heavykaolinisusedinthepreparationof
poultices.Asitisliabletobecontaminatedwith
sporebearingbacilliandotherbacteria.

59. Bentonite
Thetermbentoniteisappliedcommerciallytoany
plastic,colloidal,andswellingclayregardlessofits
geologicalorigin.Suchclaysareordinarily
composedlargelyofmineralsofthemontmorillonite
group.
Bentonitederivedfromashfallstendstobeinbeds
ofuniformthickness(fromafewmillimetresto15
m)andextensiveoverlargeareas.

60. Bentonitefromashfallsandothersourcesoccurs
worldwideinstrataspanningabroadrangeofages,
butismostabundantinCretaceousoryounger
rocks.
Bentoniteisarockoraclaybaseindustrial
material.Itisthereforeamixtureofminerals.

61. Uses
Bentoniteisusedasfillerinpharmaceuticals,and
duetoitsabsorption/adsorptionfunctions,itallows
pasteformation.Suchapplicationsincludeindustrial
protectivecreams,calaminelotion,wetcompresses,
andantiirritantsforeczema.Inmedicine,bentoniteis
usedasanantidoteinheavymetalpoisoning.
Personalcareproductssuchasmudpacks,sunburn
paint,babyandfacepowders,andfacecreamsmay
allcontainbentonite.