Seminar on study of physico-chemical methods and instrumental method analysis of

pharmaceutical dosage forms

Submitted by: Sharath H N M. Pharma 1st yearDept. Of Pharmaceutical Analysis

Content Physico-chemical methods and instrumental method analysis of

pharmaceutical dosage forms

• Sulphonamides• Barbiturates• Adrenergic drugs• Antitubercular drugs• Diuretics

INTRODUCTION• Sulphonamides: • These are the drugs or chemical substances or

chemotherapeutic drugs which are used to inhibit the growth of microorganisms without damaging host tissue.

Eg: sulphacetamide,sulphaguanidine,sulphanilamide

Sulphonamides are derived from prontosil, a prodrug that is metabolised invivo by Azo-reductase.

These are available in the form of tablets, suspensions, parentals, ophthalmic solutions,ointments.

CLASSIFICATION

• For systematic infection• Short acting: sulphadiazine, sulphathiazine• Intermediate acting:sulphamethoxazole• Long acting: sulphadoxine• For intestinal infection• Sulphasalazine• For topical application• sulphacetamide

• Analyitical methods of sulphonamides• Titrimetric methods• Diazotization reactions• Non aqueous titrations• Argetometric titrations• UV spectrometry• Colourimetry • Flourimetry

Sulphadiazine

• Chemical formula:C12H14N4O2S• Mol.wt:250.30gm• Category: Antibacterial

• Stucture

Analytical methods

• Diazotization reactions: It is commonly used for the determination of aromic amino groups in industry

• Principle: • When aromatic primary amines with nuclear –NH2 groups can be

determined quantitatively by standard sodium nitrate solution required to convert them in diazonium salts. since the formation of diazotization compounds by diazotization reaction , these method is called Diazotization reaction.

• Aromatic primary amines react with sodium nitrate in acid solution (i.e. Nitrous acid) to form diazonium salt.

• CHEMICAL REACTION

• C6H5NH2+HCL > C6H5N2CL+NACL+2H2O• NaNO2+HCL > HNO2 + NACL• KI + HCL > HI +KCL• 2HI + HNO2 > I2 +2NO + 2H20• The iodine liberated reacts with starch to form a blue colour

• ANALYTICAL METHODS

• COLOURIMETRIC ESTIMATION

• PRINCIPLE: Primary aromatic amines react with HCL+ NANO2 to form diazonium salt.The salt react with BMR reagent to form azo dye.

From stock soln B Pipette out 0.5 ml in 5 diff TT• Then add 1ml of NaNO2 + 1ml

ammonium sulphamate+1ml BMR

• Make up the volume with 10ml DW then visulize the intensity at 530nm using colourimetry.

Analysis of barbituratesIntroductionBarbiturates are the CNS depressants and popularly used as sedatives and

hypnotics.

Classificationa)Long acting: phenobarbitoneb)Short acting: butobarbitone, pentobarbitonec)Ultra acting: thiopentone,methohexitone

Mechanism of action GABA barb.potentiates

opening of cl- channel.At high conc:Directly increase cl- conductanceInhibit ca++ dependant release of neurotran smittorAt high conc:Depress voltage sensitive Na and K channels.

Analysis of barbiturates

Physical properties:Description: colorless or white crystalline power, odourlessSolubility: soluble in ethanol (95%)& in ether, sparingly in

chloroform, very slightly in water.

Chemical methods:1. Non –aqueous titration2. Gravimetry3. Acid- base titration4. Bromination5. Parri reaction6. Hydroxamic acid method

Non-aqueous titration:PrinciplePhenobarbitone is a weak acidic and react with ethanolic

sodium hydroxide in the presence of pyridine.Phenobarbitone+2NaOH phenobarbitone sod.Procedure:• Weigh accurately 0.1g of drug and dissolve in 5ml of

pyridine• Add 0.2ml of thymolpthalein solution• Ten add 10ml of silver nitrate pyridine reagent• Titrate with 0.1M ethanolic NaOH until blue colour is

obtained & perform blank

1ml of 0.1 NaOH= 0.01161g of phenobarbitoneAssay:• Weigh accurately about 0.15g, dissolve in 5ml of H2O, add

2ml of 1M H2SO4& extract with 4 quantities, each of 10ml of CHCl3.

• Filter CHCl3 extracts, evaporate the filtrate to dryness and dissolve the residue in 30ml 0f DMF, previously neutralized with 0.1m lithium methoxide.

• Titrate with 0.1m lithium methoxide, using 1 drop of 0.2%w/v solution of thymol blue in methanol as indicator, until blue colour is obtained.

• Each ml of 0.1M Li. Methoxide=0.02423g of thiopentone.

INSTRUMENTAL METHODS:Chromatographic method: Thin layer chromatography HPLC Colorimetric estimation

Thin layer chromatography:Adsorbent: silica gel (mixed layers(silica gel- G +alumina =

1:1))Sample:Material is extracted with ethanol on water bath: after

evaporating off the ethanol, residue is taken in H2O, the solution is acidified with tartaric acid, barbituric acids are extracted with ether & aliquot is applied on thin layer.

Solvent:Neutral and basic mixtures are used.Eg: CHCl3: acetone (90:10) CHCl3: ether(75:25)Detection:Nonspecifically on fluorescent layers (silicagel GF 254).Combined spray reagent of mercuric salt&

diphenylcarbazone solution.Mercurous nitrate reagent.

ADRENERGIC DRUGS:These are the drugs which with actions similar to that of

”Adrenaline or sympathetic stimulation”These drugs are also called as “sympathomimetics”

Types

Direct sympathomimeticsThey act directly as agonists on α and/ or β- adrenoreceptorsEg: adrenaline, nor- adrenaline, isoprenaline, phenylephrine etc.

Indirect sympathomimeticsThey act on adrenergic neurone to release nor- adrenaline

which acts on the adrenoreceptors.Eg: tyramine.etc.

Mixed action sympathomimeticsThey act directly as well as indirectlyEg: ephedrine, amphetamine etc.XYLOMETAZOLINE HYDROCHLORIDE:Molecular formula:C16H24N2.HClChemical name:2[4-tert-butyl 2,6- dimethylbenzyl]- 2-

imidazoline monohydrochloride.Molecular weight:280.84Appearance: white crystaline and odourless substance.Solubility: soluble in methanol& ethanol in 3% in water.

Methods of analysis:• Colorimetry • Liquid chromatography • Gas chromatography• Infrared spectroscopy

• Colorimetry: The official assay method for determination of xylometazoline

hydrochloride in the nasal solution dosage form is reported in USP.

The free base is extracted into dichloro methane, evaporated into dryness, redissolved in ethanol, made alkaline and reacted with sodium nitro ferricyanide. The colour thus developed is measured at 565 nm.

Antitubercular drugsIntroduction:These are caused by myco bacterium tuberculosis used in treatment of

chronic granulo matous disease called tuberculosis.They mainly contain amino group based on functional group, scientists

proposed different analytical methods.Classification1. First line drugs ex: isoniazid, rifampicin, streptomycin, ethambutanol2. Second line drugs ex: ethionamide. Para amino salicylic acid,

vincomycin sulphate.

• Isoniazid : physical methods:

Description: colourless crystalsSolubility: freely soluble in water, sparingly soluble in ethanol,

slightly soluble in chloroform.Melting point: it melts at 170-174o C

Chemical methods:Dissolve 0.1 gm sample in 2ml of water , add warm solution of

0.1gm vanillin in 10 ml water. Allow to stand for two minutes, yellow ppt is formed.

Assay: weigh 0.25gm of sample , dissolve in sufficient water. Add 20ml Hcl , 0.2gm potassium bromide. Titrate with 0.016M potassium bromate using methyl red solution as indicator. End point is red to yellow.

Instrumental method of analysis:Chromatography methods:TLC , colorimetry , infrared spectroscopy.Thin layer chromatography: adsorbant : silica gel GF 254Mobile phase: chloroform, methanol (9:1)Plate is coated with silica gel GF 254 , apply samples of 10µl in

different concentration 0.010% w/v and 2.0 w/v which are dissolved in acetone.

After removal of plate allow it to dry in air and examine this spot and calculate Rf value.

Concentration of sample can be determined by densitometer.

• Diuretics Introduction : Diuretics are first discovered in 1957 and its usage regulated

in 1960.These are drtugs which cause a net loss of sodium and water

in urine.CLASSIFICATION:Loop diuretics: FurosemideThiazide diuretics: Hydrochlorothiazide Potassium sparing diuretics: spiranolactoneCarbonic anhydrase inhibitors: acetazolamideOsmatic diuretics: mannitol , glycerol

• Furosemide: • Structure

• IUPAC : 4- chloro – N – furfuryl -5 – sulphamoyl anthranilic acid.

• Method of analysis of furosemide:• Titrimetric method• Spectrophotometric method: UV method, colorimetric

method• Chromatographic method: HPLC method

Titrimetric method:Dissolve 0.5gm of furosemide in 40 ml of dimethyl formamide

titrate with o.1N NaoH using bromothymol blue solution as indicator. Repeat the operation with furosemide. The diffrence between the titration represents the NaoH required.

• Colorimetric method:

Furosemide + butyl amine + cobalt chloride and acetic acid, dissolve in anhydrous methanol. Blue color is formed . Measure the absorbance at 570nm.

• Reference:• Qualitative analysis of drugs in pharmaceutical

formulations, 3rd Edition by P.D.Sethi• Higuchi,Buchman,Pharmaceutical Analysis,2nd

Edition.• The indian pharmacopeia 1996• Internet source

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