Gastrointestinal agents.pptx

7/27/2019 Gastrointestinal agents.pptx

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Gastrointestinal agents

Ana Marie L. Rubenicia, RPh


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Gastrointestinal Agents

Inorganic agents used to treat gastrointestinal

disorders includes:

1. Products for altering gastric pH

2. Protectives for intestinal inflammation

3. Adsorbents for intestinal toxins

4. Cathartics or laxatives for constipation


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Antacids

Indications: to neutralize excesshydrochloric acid which maybecausing pain or ulceration.

The stomach pH can 1 when emptyor 7 when food is present.

Hyperacidity leads to:

Gastritis general inflammation ofthe gastric mucosa.

Peptic ulcer a specifiedcircumscribed erosion. Can belocated in the lower end of theesophagus(esophageal ulcer)

Esophageal ulcer occurs whenesophageal sphincter is defectivein w/c pateint freuentlyexperience heartburn.

Gastric ulcer located in thestomach

Duodenal ulcer located in theduodenum.


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Antacids

Depending on the severity

and location of an ulcer

treatment wil range for

diet and antacid and/oranticholinergic therapy

to complete bed rest

and possible surgery.

Frequently , removal of an

emotional stress

situation in indicated.


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Antacids

Antacids are alkaline

bases used to neutralize

the excess gastric HCl

associated with gastritisand peptic ulcers.


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Antacids

While no antacid is ideal , there have been certain criteriathat have been developed. These are:

1. The antacid should not be adsorbable or cause systemicalkalosis.

2. The antacid should not be a laxative or causeconstipation.

3. The antacid should exert the effect rapidly and over along period of time.

4. The reaction of the antacid with gastric HCl should not

cause a large evolution of gas.5. The antacid should buffer in the pH 4-6 range.

6. The antacid should probably inhibit pepsin.


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ANTACIDS

SODIUM BICARBONATE

- highly water soluble

antacid with a rapid

onset of action butrelatively short

duration.

-it can cause a sharp

increase in gastric pH

up to or above pH 7.

-can cause belching and

flatulence due to the

evolution of carbon

dioxide in the presenceof acids.

- found in many

effervescent antacid

preparations.


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ANTACIDSALUMINUM HYDROXIDE USP 26

The USP 26 recognizes 2 physicalforms:

1. Aluminum Hydroxide GelUSP 26

2. Dried Aluminum Hydroxide

Gel USP 26These aluminum hydroxide gelsare ideal buffers in the Ph 3-5 region due to theiramphoteric characters.

The essential characteristics of

these gels is the fine colloidalparticles that would exhibit alarge surface area and thusgreat adsorptive powers uponwhich its therapeutic valuesdepends.

A problem with these gels isthat of a loss of antacidproperties upon aging.

Due to the product watersoluble AlCl3 of the reaction

with HCl, Al(OH)3 gel causesconstipation and occasionallynausea and vomiting.


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ANTACIDSALUMINUM HYDROXIDE

USP 26

Uses:

1. Gastric antacid and isnow widely employed in

the treatment ofhyperchlorhydria andpeptic ulcer.

2. It is also indicated forthe treatment oftoxemia due to itscapability of adsorbing

HCl, toxins, gases andbacteria. This is theadvantage of the gelapparent adsorbspepsin.

Caution: can also interferewith adsorption ofother drugs.


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ANTACIDS

CALCIUMCONTAINING ANTACIDS

This group of antacids differ from the aluminumantacids in that in their action is dependentupon their basic properties and not on anamphoteric effect.

In vitro and in vivo studies show that the calciumantacids raise the stomach pH to nearly 7.

The calcium antacids tend to be constpating andare usually found in combination with

magnesium antacids.


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CALCIUM CARBONATE USP26

Synonyms: Precipitated ChalkProperties: Practically

insoluble in water butsolubility is increased byammonium salts or carbon

dioxide. It is insoluble inalcohol and dissolves witheffervescence in dilutedacetic acid , dil HCl and dilnitric acid.

Uses: because of its fast

action calcium carbonate isone of the most popularantacids.

Its action is limited by theamount of salt that will go

into the solution. Thus, asgastric HCl consumessolubilized CaCO3, moregoes into the solution.

Most CaCO3 preparations will

be found in combination witmagnesium antacidsbecause of calciumsconstipative effects.

USP 26 recognizes Calcium

carbonate lozenges and oralsuspension.


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TRIBASIC CALCIUM PHOSPHATE NF21[Ca3(PO4)2]

Synonyms: Precipitated CalciumPhosphate, Tertiary CalciumPhosphate, Calcium Phosphate

Properties: Insoluble in water andalcohol but dissolves readily in dilHCl and HNO3.

Uses:

As an antacid in the treatment ofhyperacidity by diminishing thehydrogen ion concentration ofthe gastric HCl by the formationof primary and secondary

phosphates.It has the advantage over NaHCO3 in

that there are no gas produced.

It is also used as source of calciumfor the system but due to itsinsolubility , very little Ca is

absorbed and is therefore notavailable in acute calciumdeficiemcy.


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ANTACIDS

MAGNESIUM CONTAINING ANTACIDS-there are a large number of official antacids containingmagnesium, with the exception of magnesiumtrisilicate, they all function in the same manner.

-they are poorly soluble salts w/c only go into soln as acid

consumes the small amount of anion already insolution. Thus, it is the anion rather than themagnesium cation that confers to its antacid properties.

The magnesium cation causes this group of antacids to belaxatives. For this reason, they are susually found in

combination with Al and Ca antacids in an attempt toequalize the constipative and laxative actions


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MAGNESIUM CONTAINING ANTACIDS

MAGNESIUM CARBONATE USP 26[Mg( CO3 )4.Mg(OH)2.5H2O]

Synonyms: Carbonate of Magnesia;Magnesium Carbonate; HeavyMagnesium Carbonate

Properties: Insoluble in alc butdissolves with effervescence in dilacids.

Uses: The antacid properties are dueto the hydroxide and carbonateanions reacting with the gastricHCl.

Due to its very limited solubility,MgCO3 dissolves only ascarbonate and hydroxide arebeing consumed.

MAGNESIUM HYDROXIDE USP 26[Mg ( OH )2]

Properties: Practically insolublein water and alcohol butdissolves in acids.

Uses: Due to its basic character,it is an efficient antacid. Inhigh doses, it used as alaxative. This due to theformation of magnesium

chloride in the stomach w/cexerts a salt action in theintestinal tract causing a mildlaxative action.


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MILK OF MAGNESIA

A suspension of magnesiumhydroxide containing nlt 7%and nmt 8.5% Mg(OH)2.

To minimize the interaction ofglass containers andMg(OH)2, small amounts ofcitric acid maybe added.

Suitable flavoring agentsmay also be added.

Uses: very popular antacid andlaxative.

MAGNESIUM PHOSPHATE [Mg3(PO4)2. 5H2O

Synonym: Tertiary Magnesium

Phosphate

Properties: Readily soluble indiluted mineral acids but

almost insoluble in water.

Use: Antacid


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MAGNESIUM OXIDE USP 26(MgO)

Synonyms: Magnesia

Properties:The USP recognizes 2

varieties of medical MgO(differ indensity):

1. Light Magnesium Oxide 5grams occupy a volume ofapproximately 40 to 50 mL andhydrolyzes to Mg(OH)2 moreeasily than the heavy oxide.

2. Heavy Magnesium Oxide 5grams occupy a volume of 10 to20ml.

They are similar in composition andpurity. Upon exposure to air,they absorb carbon dioxide andmoisture.

Uses: Magnesia is employed as

laxative, diuretic and antacid. I

It also given as arsenic

antidote.

In order to prevent the formation

of a gelatinous mass, it should

be administered in about 29

times its weight of water.

The magnesia should be added towater and not the reverse in

order to avoid the formation

of hard lump


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MAGNESIUM TRISILICATE USP26(2MgO.3SiO2.xH2O)

Composition: Defined as acompound of magnesiumoxide and silicon dioxide

containing varying portions ofwater. It contain nlt 20%magnesium oxide and nmt45% of silicon dioxide.

Properties: It is assayed in termsof silicon dioxide and MgO and

must have definite SiO2/MgOratio. As the amount of SiO2increases with respect to MgO,there is lost in antacidproperties.

Use: gastric antacid especiallyvaluable in peptic ulcer.

2MgO.3SiO2.xH2O + 4H+

3SiO2.xH2O+2Mg+2H2O

The colloidal silicic acid orhydrous silica which is formedin the reaction has adsorptive

powers and could protect theulcer from further acid andpeptic attack and possibleadsorbs the pepsin.


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COMBINATION ANTACID

PREPARATION

Mixtures of antacids are made to balance the constipative effect ofcalcium and aluminum with laxative effect of magnesium. Also, amixture of an antacid with rapid onset of action and one withsupposedly longer duration of action.

a.) Aluminum Hydroxide Gel Magnesium Hydroxide

Combination: Aludrox, Wingel, Maalox, and Cremalib.) Aluminum Hydroxide Gel Magnesium Trisilicate

Combination: Gelusil, Tricreamalate, Triosgel

c.) Magaldrate chemical combination of Al(OH)3 and Mg(OH)2(Riopan)

d.) Simethicone(defoaming agent) containing antacids: Di-Gel,Mylanta. Prevent being gassy.

e) Alginic acid NaHCO3 containing antacids: Gaviscon, Foamtab. Thisformulation attemp to provide symptomatic relief of refluxesophagitis.


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PROTECTIVES AND ADSORBENTS

Ana Marie L. Rubenicia, RPh


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PROTECTIVES AND ADSORBENTS

This group of gastrointestinal agents is

commonly used for the treatment of mild

diarrhea.

Most products for the treatment of diarrhea will

consist of an

1. adsorptive-protective

2. antidiarrheal agent and possibly an

3. antibacterial agent.


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BISMUTH-CONTAINING PRODUCTS

The use of bismuth salts as antidiarrheal agentseems to be supported chiefly by tradition.

They are considered as water insoluble but a

small amount go into solution. The solublebismuth cation supposedly exerts a mildastringent and antiseptic action.

Intestinal hydrogen sulfide acts upon the

bismuth salts to form bismuth sulfide, hence, theblack stool resulting from the oral administrationof bismuth-containing preparations.


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BISMUTH SUBNITRATE USP 26

[Bi (OH)2(NO3)4.BiO(O H)]

Synonyms: Basic Bismuth Nitrate;

White Bismuth

Properties: Bismuth Subnitrate

occurs as white, slightly

hygroscopic powder which

gives an acid reaction using

blue litmus paper. It is

practically insoluble in water

and alcohol but dissolves in

HCl . It is assayed in terms of

bismuth trioxide (Bi2O3).

Bismuth subnitrate is incompatiblewith tragacanth, in whichtragacanth precipitates as a hardmass in the presence of the salt.The difficulty maybe overcome bthe addition of sodium

biphosphate or trisodiumphosphate.

Uses: it is used as an effective non-irritant intestinal antiseptic.Bismuth salts lessens gastricsecretion and reduce acidity,

hence it is employed in treatinggastric ulcers and inflammations.Bismuth Subnitrate is a commonremedy against diarrhea.


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BISMUTH SUBCARBONATE USP26 [BiO2(CO3)2. H2O]

Synonym: Basic BismuthCarbonate

Properties: It is a white or pale

yellowish white,odorless,tasteless powder which isstable in air but is slowlyaffected by light. It ispractically insoluble in waterbut dissolves in HCL with

effervescence. BismuthSubcarbonate is assayed interms of its bismuth trioxidecontent.

Uses:

It is used for its protective andantacid effect ininflammations of the stomachand bowels.

It is also given in large doses (60grams) for rendering thealimentary canal opaque to x-ray.

It is used as an astringent andadsorbent and in the

treatment of diarrhea anddysentery.


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MILK OF BISMUTH USP 26

Synonyms: Bismuth Magma,Bismuth Cream

Uses: Astringent and antacid

Composition: Milk of Bismuth

contains bismuth hydroxide andbismuth subcarbonate insuspension in water.

It is made by concerting bismuthsubnitrate to bismuth nitrate bythe addition of nitric acid. Then,by the treatment with

ammonium carbonate andammonia solution, bismuthnitrate is converted to bismuthhydroxide and subcarbonate.

ACTIVATED CHARCOL USP 26

has been as an adsorbent in thetrEatment of diarrhea. I

t is now recommended as anantidote in certain types ofpoisoning.


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KAOLIN USP XX 26

Synonyms: Porcelain Clay; ChinaClay; Bolus Alba

Properties A soft, yellowishwhite or whitish powder or in

lumps, insoluble in water andin cold dilute acids and insolutions of alkali hydroxides.It has an earthly and clay-liketaste. When moistened withwater, it assumes a darker

color and develops a markedclay-like color.

Uses: It is usually foundtogether with the vegetablecarbonate, pectin(Kaopectate, Kao-Con) andemployed as a protective sndadsorbent (Kaopectate, Kao-Con) and employed as aprotective and adborbent indiarrheal disorders.

Kaolin-containing products havebeen reported to interfere

materially with the intestinalabsorption of lincomycin.

SALINE CATHARTICS


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SALINE CATHARTICS

Saline cathartics (purgatives) are agents that quicken and increaseevacuation from bowels. Laxatives are mild cathartics . Mostproducts can be purchased without prescription hence this grouphas been widely used, abused and often overprompted by themanufacturers.

The 1972 AMA Drug Evaluation states the criteria whencathattics are properly used:

1. To ease defecation in patients with pAinful hemorrhoids orother rectal disorders.

2. To avoid potentially hazardous rises in blood pressure during

defecation in patients with hypertension, cerebral arterialdiseases.

3. To relieve acute constipation,

4. To remove solid material from the intestinal tract prior tocertain roentgenographic studies.

SALINE CATHARTICS


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SALINE CATHARTICS

4 Types of Laxatives:1. Stimulant Laxatives act by local irritation on the intestinal tract, whichincreases peristaltic activity.

2. Bulk-forming Laxatives are made from cellulose and other non-digestiblepolysaccharides which swell when wet and with the increased bulk stimulatesperistalsis.

3. Emollient Laxatives act neither as lubricants facilitating the passage ofcompacted fecal material or as stool softeners. Example is Mineral Oil.

4. Saline Cathartics act by increasing the osmotic load of the gastrointestinaltract. They are salts of poorly absorbable anions and sometimes cations. Thebody relieves the hypertonicuty of the gut by secreting additional fluids into theintestinal tract. The resolution increased bulk stimulates peristalsis.

Poorly absorbed anions that are used as saline cathartics are biphosphate,phosphate , sulfate and tartrate. Soluble magnesium salts are cathartic due tothe poorly absorbed magnesium ion. The saline cathartics are water solubleand are taken with large amounts of water. This prevents excessive loss of bodyfluids and reduces nausea and vomiting if a too hypertonic solution shouldreach the stomach.


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SALINE CATHARTICS

MONOBASiC SODIUM PHOSPHATE

USP 26 [NaH2PO4.H2O]Synonyms: Sodium Dihydrogn

Phosphate; Sodium AcidPhosphate; Primary SodiumPhosphate; Sodium Buphosphate

Properties: A colorless crystals or as

a white crystalline powder. It isodorless and is slightlydeliquescent. Its solution areacid to litmus and effervescewith sodium carbonate. These 3acidic properties are due to theacid dihydrogen phosphate

anion. The USP 26 recognizessalt in the anhydrous form andwith one or two moles of waterof hydration.

Uses: Official category is as urinaryacidifier.

It is also used as a cathartic. Thissalt is used to render the urineacidic in case of cystitis withhexamethylenetetramine

(Methenamine), as thissubstance decomposes intoformaldehyde only in thepresence of acids.


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SALINE CATHARTICS

DIBASIC SODIUM PHOSPHATE

USP 26[Na2HPO4.7H2O]

Synonyms: Dibasic SodiumPhosphate; DisodiumHydrogen Phosphate;Secondary Sodium Phosphate

Properties: Sodium Phosphateoccurs as a colorless or whitegranular salt which effervescesin warm dry air. Its solutions

are alkaline to litmus andphenolphthalein with a pH of9.5. It is freey soluble to waterand very soluble in alcohol. Itis also official with one, two,seven or twelve moles water

of hydration.

Uses: Because of the poorintestinal permeability of themonohydrogen phosphate ion,this product is widely used asa saline cathartic.

Caution: This Sodium Phosphate(Dibasic) should never beconfused with the commercialtribasic sodium phosphatewhich is very alkaline andcaustic and should be used for

intestinal purposes.


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SALINE CATHARTICS

POTASSIUM SODIUM TARTRATE USP

26 KNaC4H4O6.4H2OSynonyms: Rochelle Salt; Seignette

Salt

Properties: Occurs as colorlesscrystals or as a white crystalline

powder having a cooling salinetaste. Because of it efflorescesslightly in warm, dry air , thecrystals are often coated with awhite powder. It is freely solublein water and practically insolublein alcohol.

Uses: The main use of Rochelle Saltin therapeutics is as cathartic, itsactivity ranging from mildlaxative to the more potenthydragogue depending upon thedose administered.

It is a pharmaceutical necessity and

an ingredient of Seidlitz powderwhich is in the form in which

potassium sodium tartrate is

administered as cathartic. It is

an effervescent preparation and

is a palatable product.Rochelles Salt is one of the

components of the useful

reagent, Fehlings Solution,

officially called Alkaline Cupric

Tartrate. This is an example ofthe chelate complexation

wherein the concentration of the

cupric is very little and is not

precipitated by the NaOH

present in the reagent.


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SALINE CATHARTICS

MAGNESIUM SULFATE USP 26[MgSO4.7H2O]

Synonyms: Epsom Salt; Bitter Salt

Uses: An active cathartic operating

with but little pain or nausea and

producing watery stools.

Parenterally, it is used as an

anticonvulsant, It I also used locally

in saturated solution for its

anecthetic effect in sprains and

bruises and appears to be possessedodFsome sort of antiphlogistic

action.

MAGNESIUM CITRATE USP 26

Synonyms: Citrate of Magnesia;Purgative Lemonade

NON OFFICIAL SALINE CATHARTICS

1. SODIUM SULFATEGlaubers Salt

2. POTASSIUM PHOSPHATE Dibasic

Potassium Phosphate, Dipotassium

Hyrogen Phosphate, DKP

3 POTASSIUM BITARTRATE Cream of

Tartar, Potassium Acid Tartrate,

Potassium Hydrogen Tartrate

4. CALOMEL Mercurous Chloride, Mild

Mercury Chloride

Gastrointestinal agents.pptx

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