Limits to relying solely on pharmacokinetic/pharmacodynamic studies for an exotic animal formulary
Carpenter, J. W., & Harms, C. A. (2022, December 2). JOURNAL OF SMALL ANIMAL PRACTICE.
We found your article, ‘Evaluation of sources cited by an exotic animal formulary for supporting drug dosages and reference intervals in mammals’ (Golden et al., 2022: JSAP 2022:1–10) to be interesting and well written. However, the authors do not fully convey the nature, complexity and evolution of our formulary, a reference that has evolved and expanded over the last 30 years. For the Exotic Animal Formulary 5 E (Carpenter 2018), 29 of the most recognised specialists in our field evaluated published drug dosages, related biologic and medical information and references, and selected those that would be most clinically useful and relevant to the practitioner. Based on our collective clinical experience and after reviewing many thousands of references, approximately 2400 references were selected to be cited. Not only are all drug dosages referenced, but almost all have ‘comments’, including stating if the dosage is based on a pharmacokinetic (PK) or pharmacodynamic (PD) study. ‘This book is not intended to replace existing medical resources or the use of sound medical judgement…This formulary assumes that the reader has a reasonable understanding of veterinary medicine.’ ‘All users…should empirically evaluate all dosages to determine that they are reasonable prior to use.’ ‘…Until more pharmacokinetic, efficacy, and safety studies…are conducted, most dosages used in these species are based on empirical data, observations, and experience.’ Although the authors are correct in suggesting that PK/PD studies are the gold standard, there are still relatively few PK/PD studies performed in exotic animals. So as we continue to conduct PK/PD studies on drugs used in exotic species, we, out of necessity, need to cite dosages and references from the most reliable sources possible. Although a formulary for exotic animals based solely on PK/PD studies would be ideal, at the present time that formulary would be extremely brief and only of minimal use to clinicians.