COMPOUNDING HOTLINE

Q: Do you have information on compounding an oral form of vancomycin from the intravenous solution that is more palatable, as well as stability information on the compounded product?

A: Vancomycin HCl, a glycopeptide antimicrobial, is a tan-tobrown odorless powder with a bitter taste. It is freely soluble in water and only slightly soluble in ethanol. A 5% aqueous solution of vancomycin HCl has a pH of 3.0 to 5.0. When correctly reconstituted, vancomycin for oral solution has a pH of 2.5 to 4.5. Because of this low pH, incompatibilities with other drugs may occur. The drug is produced from Streptomyces orientalis and has not less than 900 mcg/mg of vancomycin. It has microbial activity against most gram-positive bacteria, but gram-negative bacteria, mycobacteria, and fungi are resistant. Vancomycin acts by interfering with cell-wall synthesis. It is poorly absorbed when administered orally. When given intravenously, the pharmacokinetics vary widely among individuals: t1/2 among otherwise healthy patients can range from 3 to 13 hours; longer times have been noted in patients with impaired renal function. The drug is well distributed, but it does not penetrate to the cerebrospinal fluid unless meningitis is present. It is excreted through the kidneys; 90% of a dose appears in the urine within 24 hours. Its poor absorption from the gut and its activity profile make it a candidate for the treatment of Clostridium difficile, and it has a major role in the treatment of methicillin-resistant staphylococcus infections.

A special consideration for compounding oral solutions is to ensure that a commercially manufactured product is not available, or that there is a particular, patient-specific, documented medical contraindication to the use of the commercially manufactured product (such as an allergy to a component in the commercial product) to ensure that compounding is within US Pharmacopeia (USP) and FDA guidelines.

The following formulation was suggested for the preparation of 100 mL of a palatable vancomycin oral solution extemporaneously:

1. Accurately weigh/measure the ingredients.

2. Dissolve the vancomycin HCl, Stevia, and saccharin Na in about 40 mL purified water. Mix thoroughly.

3. Add raspberry flavor to 40 mL glycerin. Mix thoroughly.

4. Add the glycerin solution in (3) to the solution in (2).

5. Add sufficient purified water to make 100 mL total volume, and mix thoroughly.

Package and label (in tight, light-resistant containers).

This product should be stored in the refrigerator and can be assigned a 14-day beyond-use date, according to USP 28 <795>, Pharmacy Compounding: Non-Sterile Preparations.

E-mail your compounding questions to compounding@pharmacytimes.com

Mr. Erickson is director of professional affairs at Gallipot Inc.