MATERIALS
  • Cellulose Acetate Phthalate 64 g
  • Rifampicin 800 g
  • Polyethylene Glycol 4000 6.4 g
  • Water 1200 ml
  • Hydrochloric Acid 0.5 ml
  • Dichloromethane 200 ml
  • Isopropyl Alcohol 100 ml

PROCEDURE
  1. Dissolve Cellulose Acetate Phthalate and Polyethylene Glycol 4000 in Isopropyl Alcohol & Dichloromethane mixture
  2. Disperse rifampicin in water containing 0.5 ml of Hydrochloric Acid to make a slurry and keep on a water bath at50° C.
  3. Add Cellulose Acetate Phthalate solution to the slurry with constant stirring.
  4. Filter off the microcapsules and dry them.

The above mentioned microcapsules of Rifampicin may be blended with other anti-tubercular drugs and suitable excipients to formulate into tablets, capsules or suspension.



CHEMICAL AND PHYSICAL PROPERTIES


Cellulose Acetate Phthalate/Hydroxypropyl Methyl Cellulose Phthalate


Physical State : white to off-white powder or flakes
Taste : Tasteless
Odor : Odorless
Molecular Formula : C36H44O19)N
Solubility: in water swells to form viscosity colloidal solution. Soluble in most organic solvents (methanol,ethanol and acetone, ehtanol and dichloromethane), Insolube in hot water, alcohol
Molecular Formula : C36H44O19)N
Melting Point : 145 °C
Density : 0.6 g/ml at 25 °C
Particle size: 100 percent through 100mesh sieve.
Use: An enteric coating agent is used to protect drugs from degradation by gastric acid or to prevent them from causing side effects in the stomach. HPMCP was developed and used originally as an enteric coating agent, its favroable properties have led to extension of its range of applications into other fields, inlcuding sustained release preparations, binders and microcapsule bases, in the above-mentioned applications.HPMCP is usually used alone, but can be used in combination with other polymers, as in the case of the sustained release preparations.

Rifampicin

Molecular formula : C43H58N4O12
Molecular weight : 822.96
Chemical names : 3-[[(4-methyl-1-piperazinyl)imino]methyl)]rifamycin 5,6,9,17,19,21-hexahydroxy-23-methoxy-2,4,12,16,18,20,22-heptamethyl-8-[N-(4-methyl-1-piperazinyl)formimidoyl]2,7(epoxypentadecal[1,11,13]trienimino)-naphtho[2,1-beta]furan-1,11(2H)-dione 21-acetate
Colour : Red to orange
Form and Description : Powder
Odor : Odourless.
Solubility : Very slightly soluble in water (1 g in approximately about 762 mL water [pH < 6]), acetone, carbon tetrachloride, alcohol, ether. Freely soluble in chloroform, DMSO; soluble in ethyl acetate and methyl alcohol and
tetrahydrofuran. Solubility in aqueous solutions is increased at acidic pH.
Melting point : 138 to 188 °C
pKA : Rifampicin has 2 pKa since it is a Zwitterion, pKa 1.7 related to 4-hydroxy and pKa 7.9 related to 3-piperazine nitrogen
pH : 1% suspension in water has pH 4.5 to 6.5.

Shelf-life of the substance : As a dry powder it is stable for more than five years at 25°C. As lyophilized reparations for intravenous use it is stable for at least two years before reconstitution

Storage conditions : Rifampicin should be protected from air, light and excessive heat and moisture. Store at temperature not exceeding 40 °C (preferably between 15 to 30 °C) in airtight containers in an atmosphere of nitrogen. Protect from light by amber coloured bottles.

Polyethylene Glycol 4000

Synonyms: PEG; Carbowax®; Polyglycol; Polyethylene glycol 200, 300, 400, 600,1000,1450, 3350, 4000, 6000, 8000 and 20000.
Molecular Weight : Not applicable to mixtures.
Chemical Formula: (C2H4O) n.H2O
Storage : Keep in a tightly closed container, stored in a cool, dry, ventilated area. Protect against physical damage. Containers of this material may be hazardous when empty since they retain product residues (dust, solids, vapors, liquid); observe all warnings and precautions listed for the product.
Appearance: Clear liquid or white solid.
Odor: Mild odor.
Solubility: Soluble in water.
Density: range: 1.1 to 1.2 (increases as molecular weight increases)
pH: No information found.
Melting Point: Melting point increases as molecular weight increases: PEG 400 = 4-8C (39-46F) PEG 600 = 20-25C (68-77F) PEG1500 = 44-48C (111-118F) PEG 4000 = 54-58C (129-136F) PEG 6000 = 56-63C (133-145F)
Vapor Pressure (mm Hg): Vapor pressure is very low; as molecular weight increases, vapor pressure decreases.
Stability: Stable under ordinary conditions of use and storage.
Hazardous Decomposition Products: Carbon dioxide and carbon monoxide may form when heated to decomposition.
Hazardous Polymerization: Will not occur.
Incompatibilities: Incompatible with polymerization catalysts (peroxides, persulfates) and accelerators, strong oxidizers, strong bases and strong acids.


Hydrochloric Acid
Hydrochloric acid is a solution of hydrogen chloride (HCl) in water, that is a highly corrosive, strong mineral acid with many industrial uses
Molecular Formula : HCl in water (H2O)
Molecular weight 36.46 g/mol (HCl)
Appearance : Clear colorless to light-yellow liquid
Density : 1.18 g/cm3 (variable, value for assay 36-38% w/w)
Melting Point : –27.32 °C (247 K) 38% solution.
Boiling point : 110 °C (383 K), 20.2% solution; 48 °C (321 K), 38% solution.
Solubility in water : Miscible
Solubility : soluble in diethyl ether, ethanol, methanol Acidity
(pKa) –8.0
Refractive index (nD) 1.342
Viscosity : 1.9 mPas at 25 °C,31.5% solution

Dichloromethane /Methylene Chloride

Structural formula : CH2Cl2
Molecular weight : 84.93
Colour : Clear, colourless.
State/form : Volatile liquid.
Boiling point : 39.5 to 40.5 °C
Melting point : -96.7 °C
Autoignition temperature:624 °C
Specific gravity : 318 to 1.322
Vapour density : 2.93 (air = 1.02)
Vapour pressure : 46.5 kPa
Refractive index: 1.4327 (20 °C)
Percentage in "saturated" air : 55% (25 °C)
Water solubility : 2 g/100 mL Soluble in ethanol, ether and dimethylformamide.

Odor : It has a sweetish chloroform-like odour above 300 ppm which becomes unpleasant to most people at about 1000 ppm. At 2300 ppm it is strong and intensely irritating.

Flammable regions may exist above -9 °C. Methylene chloride is flammable at concentrations of 12 to 15% in ambient air, but only with elevated temperature and pressure, or in oxygen-enriched air.

Conversion factors: 1 ppm in air (3.5 mg/1000 L)[1 mg/1000 L = 0.29 ppm in air]

Isopropyl Alcohol 

Chemical name: Isopropyl alcohol
Molecular weight: 60.09
Structural formula: CH3-CH(OH)-CH3
Colour : Colourless
State/form : Liquid-other
Boiling point: 82.5°C
Melting point: 89.5°C
Flash point: 11.7°C (closed cup,17°C (open cup)
Autoignition temperature: 455.6°C
Relative density: 0.785 (Water = 1)
Vapour pressure: 4399.62 Pa at 20°C, 7879.33 Pa at 30°C
Solubility: In water in all proportions at 20°C, In alcohol in all proportions at 20°C, In ether in all proportions at 20°C. Also soluble in acetone, benzene and chloroform,insoluble in salt solutions.

Relative molecular mass: 60.09C: 59.96%; H: 13.42%; O: 26.62%)
Viscosity: 0.00243 Poises (2.43 cP) at 20°C
Odour: Slight odour resembling a mixture of ethanoland acetone.
Taste: Slightly bitter taste

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