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Q: A patient wants me to compound colchicine oral capsules, and the physician is willing to prescribe them. How should I proceed?
A: A New Drug Application for Colcrys (colchicine 0.6 mg) was approved by the FDA on July 29, 2009. Patents and exclusivities run far into the future. If the drug product is in short supply or another valid reason for compounding exists (See Compliance Policy Guide [CPG] Section 460.200 at www. FDA.gov), presumably compounding the preparation for this patient would be permissible according to USP 34<795> and the FDA CPG.
Please be aware of the toxicity potential, especially for patients with reduced renal or hepatic function (avoid P-glycoprotein [P-gp] inhibitors and/or strong cytochrome P450 [CYP] 3A4 inhibitors in these patients). In patients with normal renal and hepatic function taking colchicine, critically evaluate whether use of P-gp inhibitors and/or CYP3A4 inhibitors is required.
Q: I cannot obtain the Polysorbate 20 that is included in the suppository formulations I have. What should I do?
A: Polysorbates are polyoxyethylene sorbitan fatty acid esters and are surface-active agents. They are often included in suppository formulations as pharmaceutic aids to ease removal of the finished dose form from the mold. Polysorbates 20, 60, and 80 are included in the FDA Inactive Ingredients Guide for use in formulating intramuscular, intravenous, oral, rectal, topical, and vaginal preparations.
Although the polysorbates contain varying proportions of fatty acids used to manufacture them, incompatibilities are similar. Their hydrophilic-lipophilic (HLB) values and viscosities vary. Polysorbate 20 has an HLB value of 16.7 and a viscosity of 400 mPas; Polysorbate 60 has an HLB value of 14.9 and a viscosity of 600 mPas; Polysorbate 80 has an HLB 15 and a viscosity of 425 mPas. Polysorbate 60 and Polysorbate 80 exhibit behavior similar to Polysorbate 20 and are reasonable substitutes at about a 1% concentration.
Mr. Erickson is director of professional affairs at Gallipot Inc.
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