Flucytosine

METHOD OF PREPARATION

1. Calculate the required quantity of each ingredient for the total amount to be prepared.

2. Accurately measure each ingredient. Ohtain the required number of Ancobon (flucytosine) 250-mg or 500-mg capsules to provide the flucytosine for this preparation.

3. Reinove the contents from the capsules, and pulverize the powder.

4. Add the glycerin and form a smooth paste.

5. Tn portions, incorporate the Ora-Plus and mix well.

6. Add sufficient Ora-Sweet or Ora-Sweet SF to volume and mix well.

7. Package and label.

PACKAGING

Package in tight, light-resistant containers.1

LABELING

Keep out of reach of children. Use only as directed. Shake well before using.

STABILITY

A beyond-use date of 60 days is appropriate for this preparation.1-2

USE

Flucytosine is used as an antifungal agent.

QUALITYCONTROL

Quality-control assessment can include weight/volume, pH, specific gravity, active-drug assay, color, rheological properties/pourability, physical observation and physical stability (discoloration, foreign materials, gas formation and mold growth).3

DISCUSSION

Flucytosine (C^sub 4^H^sub 4^FN^sub 3^O, MW 129.09) occurs as a white to offwhite crystalline powder that is odorless or has a slight odor. It is sparingly soluble in water and slightly soluble in alcohol. Flucytosine is a fluorinated pyrimidine analog that is used to treat serious infections caused by susceptible strains of Candida or Cryptococcus neoformans and to treat chromomycosis caused by susceptible fungi.1,4

Glycerin (C^sub 3^H^sub 8^O^sub 3^, MW 92.1, glycerol, 1,2,3-propane triol) occurs as a clear, colorless, odorless, viscous, hygroscopic liquid with a taste about two thirds as sweet as that of sucrose. It is miscible with water, methanol and 95% ethanol; practically insoluble in oils and chloroform and slightly soluble in acetone. It should be stored in airtight containers in a cool place. It is not prone to oxidation but will decompose on heating. When mixed with water, ethanol and propylene glycol, the mixtures are chemically stable.5

Ora-Plus is an oral suspending vehicle that accepts dilution of up to 50% or more with water, flavoring agents or syrups and still retains its suspending properties. It has a pH of approximately 4.2 and an osmolality of about 230 mOsm/Kg. It is a thixotropic vehicle with a viscosity of approximately 1000 cps at 25°C. It contains purified water, microcrystalline cellulose, sodium carboxymethylcellulose, xanthan gum, carrageenan, sodium phosphate and citric acid as buffering agents; simethicone as an antifoaming agent; and potassium sorbate and methylparaben as preservatives.6

Ora-Sweet syrup is a flavoring vehicle for oral extemporaneous preparations. It is flavored with a citrus-berry flavor blend and contains glycerin and sorbitol to prevent "cap-lock," a problem associated with many syrups. It is buffered to a pH of approximately 4.2 and has an osmolality of about 3240 mOsm/Kg. It contains purified water, sucrose, glycerin, sorbitol (5%), flavoring, sodium phosphate and citric acid as buffering agents and potassium sorbate and methylparaben as preservatives.6

Ora-Sweet SF is a flavoring vehicle for oral extemporaneous preparations. It is a sugar-free, alcohol-free syrup flavored with a citrus-berry flavor blend. It is buffered to a pH of approximately 4.2 and may be used alone or in combination with other vehicles. It will tolerate dilution up to 50% with dissolved actives in water or suspending agents and still retain an acceptable taste. It has an osmolality of 2150 mOsm/Kg. It contains water, sodium saccharin, xanthan gum, glycerin, sorbitol, citric acid and sodium citrate as buffers; methylparaben, propylparaben and potassium sorbate as preservatives; and flavoring agents.6

REFERENCES

1. US Pharmacopeial Convention, Inc. United States Pharmacopeia 26NationalFormulary 21. Rockville, MD:US Pharmacopeial Convention, lnc.;2003:794-795, 2197-2201, 2561.

2. Alien LV Jr, Erickson MA. Stability of acetazolamide, allopurinol, azathioprine, clonazepam and flucytosine in extemporaneously compounded oral liquids. Am J Health Syst Pharm 1996;53:1944-1949.

3. Alien LV Jr. Standard operating procedure for performing physical quality assessment of oral and topical liquids. /JPC1999;3:146-147.

4. McEvoy GK. AHFS Drug Information-2003. Bethesda, MD:American Society of Health-System Pharmacists;2003:102.

5. Price JC. Glycerin. In :Rowe RC, Sheskey PJ, Weller PJ, eds. Handbook of Pharmaceutical Excipients. 4th ed. Washington, DC:American Pharmaceutical Association;2003:257-259.

6. Ora-Plus/Ora-Sweet/Ora-Sweet SF [product information]. Minneapolis, MN:Paddock Laboratories, Inc.

Copyright International Journal of Pharmaceutical Compounding Mar/Apr 2004
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