Thursday, June 27, 2013

Textbook for Vets Addresses Issues Relating to Compounded Drugs

Textbook of Veterinary Internal Medicine
By Stephen J. Ettinger, DVM, DACVIM and Edward C. Feldman, DVM, DACVIM
Chapter 160 – Compounding Drugs
Ron Johnson
One of the greatest challenges to veterinarians can be the availability of appropriate drug dosage forms that enable easier dosing of small dogs and cats and improve owner compliance. Although advances have been made with new drugs and dosage forms approved for veterinary medicine, clearly there is an unmet need with drug formulation options and dosages. As such, drugs approved in one animal species are frequently used in another species, including human-approved drugs. Compounded drugs can alleviate some of the drug-related issues facing veterinary medicine provided compounding is approached in a rational manner. There is little doubt that compounded drug formulations can offer effective and safe delivery options to veterinary patients. Support for this comes from the large number of pharmacies offering compounded drug products for veterinary patients and the increasing number of peer-reviewed journal articles that involve compounded veterinary …

Pharmaceutical Issues
Compounding by medical professionals and pharmacists is not equivalent to the formulation of commercially manufactured products by reputable pharmaceutical firms. Drug formulation requires an understanding of the physical and chemical characteristics of the active pharmaceutical ingredient, along with the other agents (e.g., vehicles, excipients) used to produce the administered dosage form, in order to maintain the administered drug's effectiveness and safety profile. To this end, a compounded drug must possess adequate purity, potency, and demonstrate stability (shelf life) to maintain acceptable bioavailability (extent of systemic drug absorption) of the active pharmaceutical ingredient, but not produce toxicity or an ineffective preparation. However, for the vast majority of drugs compounded by veterinarians and most pharmacists, there is a lack of adequate pharmaceutical and clinical testing to ensure …

Transdermal Delivery of Drugs in Organogels
Transdermal administration of drugs for animals has the potential to be effective, safe, and can certainly enhance compliance. Absorption of drug via the transdermal route is primarily passive. As such, ideal molecules for this route of delivery are low molecular weight (<400 Daltons), lipophilic, and soluble in both water and oil.[10,11] Attention in veterinary medicine has focused on transdermal delivery of various drugs in organogels formulated for pulsed (single dose) therapy versus continuous release reservoirs (e.g., fentanyl patch (Duragesic).[12]
The growing list of drugs available in transdermal organogel formulations from compounding pharmacists includes antimicrobials, anticonvulsants, hormones, antineoplastics, prokinetic drugs, analgesics, and antiinflammatory agents. The vast majority of these compounded products are prepared in a pluronic lecithin organogel (PLO) vehicle. Lecithin is an emulsifying agent that forms a viscous gel when …
Compounding should be conducted in accordance with good pharmacy and compounding practices, relevant scientific literature, and applicable state laws. Pharmacy facilities used for compounding should have adequate room and equipment, be maintained in a clean and sanitary condition according to standard operating procedures in order to be effective, and prevent contaminations and errors. The USP 31-NF 26 contains a general chapter <1075> that addresses components of good compounding practices. These include responsibilities of the compounder, compounding facilities and equipment, recommendations for minimal training, and requirements for product packaging, labeling, and record keeping.[8]Importantly, there is now recognition of a separate veterinary compounding category by the USP-NF. The FDA Center for Drug Evaluation and Research has put forth a concept paper that evaluates drug products for human use that …
1..  U.S. Code of Federal Regulations, Title 21—Food and Drugs: Part 530, Extralabel Drug Use in Animals, 1994.
2.. Center for Veterinary Medicine, US Food and Drug Administration Web site: Compounding of Drugs for Use in Animals.  Compliance Policy Guide. Ch 6 608.400. Available atAccessed August 2008
3.. Geyer RE: Extralabel drug use and compounding in veterinary medicine. Food Drug Law J  1997; 52(3):291-295.
4.. Davidson G: The compounding controversy: what veterinarians should know to protect themselves and their patients. J Am Anim Hosp Assoc  2003; 39:13-17.
5.. Jordan DG: Pharmacist compounding vs veterinarian compounding: similarities and differences. J Am Vet Med Assoc  1994; 205(2):256-260.
6.. Riddell MG: AVMA's position on compounding for animals. Int J Pharm Comp  2005; 9(3):247-248.
7.. Papich MG: Drug compounding for veterinary patients. Am Assoc Pharm Sci  2005; 7(2):E281-E287.
8..  United States Pharmacopeia: Good compounding practices, The United States Pharmacopeia 31-National Formulary 26, Rockville, Md, 1075:500-503, 2008.
9..  United States Pharmacopeia: Pharmaceutical compounding-nonsterile preparations, The United States Pharmacopeia 31-National Formulary 26, Rockville, Md. 795:315-319, 2008.
10.. Marks SL: Transdermal therapeutics. J Am Anim Hosp Assoc  2003; 39:19-21.
11.. Riviere JE, Papich MG: Potential and problems of developing transdermal patches for veterinary applications. Adv Drug Deliv Rev  2001; 50:175-203.
12.. Davidson G: Update on transdermals for animal patients. Int J Pharm Comp  2005; 9(3):178-182.
13.. Bennett N, Papich MG, Hoenig M, et al: Evaluation of transdermal application of glipizide in a pluronic lecithin gel to healthy cats. Am J Vet Res  2005; 66:581-588.
14.. Hoffman SB, Yoder AR, Trepanier LA: Bioavailability of transdermal methimazole in a pluronic lecithin organogel (PLO) in healthy cats. J Vet Pharmacol Ther  2002; 25:189-193.
15.. Sartor LL, Trepanier LA, Kroll MM, et al: Efficacy and safety of transdermal methimazole in the treatment or cats with hyperthyroidism. J Vet Intern Med  2004; 18(5):651-655.
16.. Center for Drug Evaluation and Research, U.S. Food and Drug Administration: Drug Products That Present Demonstrable Difficulties for Compounding Because of Reasons of Safety or Effectiveness.  Rockville, Md, FDA Concept Paper, 2000.
17.. Davis J: Compounding for creatures: what works. Int J Pharm Comp  1999; 3(3):182-185.

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