Ganciclovir

METHOD OF PREPARATION

Note: If capsules are used to prepare this formulation, the procedure should be performed in an exhaust chamber.

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

2. Accurately weigh and/or measure each ingredient.

3. Pulverize the contents of the capsules, if used, to a fine powder.

4. Slowly add the Ora-Sweet or Ora-Sweet SF in portions, with thorough mixing to volume and mix well. (Note: This can also be accomplished by placing the powder in a calibrated bottle and adding the vehicle in portions, with shaking after each addition; this minimizes exposure to the drug.)

6. Package and label.

PACKAGING

Package in tight, light-resistant containers.

LABELING

Keep out of reach of children. Use only as directed. Shake well before taking. Use cytotoxic drug precautions.

STABILITY

A beyond-use date of 120 days can be used for this preparation.1·2

USE

Ganciclovir oral liquid is used as an antiviral agent.

QUALITY CONTROL

Quality-control assessment can include weight/volume, pH (pH 4 to 4.5), specific gravity, active drug assay, color, rheological properties/pourability, physical observation, and physical stability (discoloration, foreign materials, gas formation, mold growth).1

DISCUSSION

Ganciclovir is a synthetic purine nucleoside analog of guanine that has antiviral activity. It is structurally and pharmacologically related to acyclovir. Ganciclovir is used in the treatment of cytomegalovirus infections (retinitis, extraocular infections, gastrointestinal infections, pneumonitis, hepatobiliary infections), prevention of cytomegalovirus disease in HIV-infected individuals, prevention of cytomegalovirus disease in transplant recipients, and treatment of other viral infections.4

Ganciclovir sodium (C^sub 9^H^sub 12^N^sub 5^NaO^sub 4^, MW 277.21, Cytovene) occurs as a white to off-white crystalline powder. It is soluble 4.3 mg/mL at pH 7 in water at 25°C. The aqueous solubility is relatively constant between pH 3.5 and 8.5 but increases substantially in strongly acidic or basic solutions. It has two pK^sub a^ values, 2.2 and 9.4. Ganciclovir sodium is soluble 3 mg/mL in water at 25°C at neutral pH. Ganciclovir concentrations greater than 10 mg/mL may crystallize.2 Ganciclovir is commercially available as 250-mg oral capsules and as ganciclovir sodium for parenteral injection in 500-mg vials. The capsules (Cytovene) also contain croscarmellose sodium, magnesium stearate, and povidone; the gelatin shells consist of gelatin, titanium dioxide, yellow iron oxide, and FD&C Blue No. 2.5

Ora-Sweet syrup is a flavoring vehicle for oral extemporaneous preparations. It has a citrus-berry flavor blend and contains glycerin and sorbitol to prevent "cap-lock" problems associated with many syrups. It is buffered to a pH of approximately 4.2 and has an osmolality of about 3,240 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 sugar-free, alcohol-free syrup is a flavoring vehicle for oral extemporaneous preparations. It has 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 a dilution to 50% with dissolved actives in water or suspending agents and still retain an acceptable taste. It has an osmolality of 2,150 mOsm/kg. It contains water, sodium saccharin, xanthan gum, glycerin, and sorbitol; citric acid and sodium citrate as buffers; methylparaben, propylparaben, and potassium sorbate as preservatives; and flavoring agents.7

References

1. Anaizi NH, Swenson CF, Dentinger PJ. Stability of ganciclovir in extemporaneously compounded oral liquids. Am J Health Syst Pharm 1999; 56(17): 1738-1741.

2. US Pharmacopeial Convention, Inc. USP-Pharmacists' Pharmacopeia. Rockville, MD: US Pharmacopeial Convention, Inc.; 2005: 408-431, 686.

3. Allen LV Jr. Standard operating procedure for quality assessment of oral and topical liquids. IJPC 1999; 3(2): 146-147.

4. McEvoy GK, ed. AHFS Drug Information-2005. Bethesda, MD: American Society of Health-Systems Pharmacists; 2005: 788-800.

5. [No author listed.] Physicians' Desk Reference. 58th ed. Montvale, NJ: Thomson PDR; 2004: 2894-2900.

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

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

Copyright International Journal of Pharmaceutical Compounding Nov/Dec 2005
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