Pacific Tide An informational newsletter

Transcription

1 Pacific Tide An informational newsletter Pacific Veterinary Specialists & Emergency Service st Avenue Capitola, CA Specialty ~Emergency March 2015 Volume 3, Issue 1 Pacific Veterinary Specialists Monterey 2 Harris Court Suite A-1 Monterey, CA Monterey Office or Capitola About our Author Bryn Hoffman, MVB Dr. Bryn Hoffman, MVB, joins Pacific Veterinary Specialists, as an addition to our Internal Medicine Service. Dr. Hoffman received her BS from Cornell University in 2005 & her Doctorate in Veterinary Medicine from University College-Dublin in Ireland in She comes to us from Virginia-Maryland Regional College of Veterinary Medicine where she completed her threeyear residency as Chief Resident of small animal internal medicine and where she assisted in instruction of 4thyear veterinary students & interns. Dr. Hoffman is available Wednesday through Saturday in Capitola for Internal Medicine consults and same day referrals. Bryn Hoffman, MVB

2 Tidbits from the 2015 ACVIM Forum By: Bryn Hoffman, MVB Medical Marijuana: The next miracle drug for canine epilepsy and beyond? At this point, most of us have been asked by a client about the possibility of using medical marijuana to treat their pet s various ailments, with particular interest focused on its potential use to address anticonvulsant resistant epilepsy. While marijuana-derived compounds show promise in the treatment of epilepsy and beyond, there is much work to be done before they can reach their true potential in both human and veterinary medicine. The two main pharmacologically active compounds in the Cannabis plant are tetrahydrocannabinol (THC) and cannabadiol (CBD). THC acts on only 2 endogenous cannabinoid receptors and primarily produces the psychotropic effects associated with marijuana use. Dogs are much more sensitive to the psychotropic effects of THC than humans are, and this is one of the main limitations to using products directly derived from the cannabis plant. CBD, on the other hand, acts on a variety of receptors and has a more widespread effect on the brain, including anti-epileptic, anti-inflammatory, anti-spastic, anti-oxidant, and analgesic effects. Unfortunately, CBD has limited oral bioavailability ( ~6% in people, 0-13% in dogs) due to high first pass metabolism in the liver. Cannabis plants have, on average, a 1.2% THC concentration and only ~0.2% CBD concentration, indicating that the use of medicinal products directly derived from the unaltered Cannabis plant is unlikely to achieve serum concentrations of CBD with therapeutic effect, while producing undesirable psychotropic effects associated with the THC content. Thus there is a need for synthetic or purified medications containing solely CBD in order to harness the medicinal potential of marijuana. Three such licensed products exist for humans, used in the treatment of spasticity associated with multiple sclerosis, and nausea/vomiting associated with chemotherapy. Thus far, there are no licensed products for the treatment of epilepsy. The mechanism by which CBD limits epileptic seizures is not known, but the primary hypothesis is that it decreases glutamate-mediated neuronal excitation. Given the range of receptor types that CBD acts on in the nervous system, the reality is that multiple mechanisms are likely to contribute. Studies in mice have revealed significant anti-convulsant activity of CBD in experimental models of epilepsy. These studies have yet to be done in dogs, and those done to date in naturally-occurring human epilepsy have failed to show significant reduction in seizure frequency with use of purified CBD products. In a survey study of neurologists prescribing medical marijuana

3 for their anticonvulsant-resistant epileptic patients, less than 40% of responding practitioners reported a positive response in their patients. Thus there is a huge gap between the public s perception of the efficacy of medical marijuana (often derived from anecdotal reports published on the internet) and what is actually born out in the scientific literature and the experience of medical practitioners prescribing these products. In conclusion, marijuana-derived compounds derived from the cannabis plant have huge potential in the treatment of a wide variety of diseases. However, it will be purified CBD medications, not products containing the unaltered cannabis plant, that will have the greatest benefit and there are few of these products currently on the market. Furthermore, there is currently no intention to license veterinarians to legally prescribe marijuana-derived products in states where these products are legalized for human use, so we are a long way off from commonplace use in veterinary medicine from both a legal and scientific perspective. Speaking of Appetite Stimulants Perhaps the most clinically-relevant project to come out of this year s research poster abstracts is the use of transdermal mirtazapine gel as an appetite stimulant in cats. Many of us are managing feline patients in end-stage renal failure or GI small cell lymphoma that have declining appetites and whose owners have difficulty giving oral medications, so a transdermal option is an exciting alternative. A group at Colorado State University tested a transdermal mirtazapine gel in groups of clinically normal purpose-bred and client-owned cats. They found that dosages ranging from mg transdermally daily for 6 days (higher than our typical oral dose of mg every hours) stimulated a significantly higher food-intake in these cats than when they were given a placebo. The food-intake was comparable to or higher than that achieved by the same cats given the standard oral dose of mirtazapine. These results were achieved despite the fact that the concentration of the compounded mirtazapine gel varied significantly from the intended concentration. The transdermal product proved safe after 6 days of use, but it is important to note that they have not as of yet tested the safety of the transdermal product for long-term use. ( Currently, Lauden s Compounding Pharmacy in Capitola and A&O Specialty Pharmacy in Salinas is willing to formulate a transdermal mirtazapine product) And the award for this year s hot topic in Veterinary medicine goes to By far the hottest topic at the Forum this year was the emerging use of immunotherapy in veterinary oncology. Immunotherapy is coming to fruition in the treatment of canine lymphoma, with the upcoming release of a canine anti-cd20 antibody for the treatment of large, B-cell lymphoma, the most common lymphoma type encountered in dogs. The antibody binds to the CD20 receptor expressed by most B cell lymphocytes and stimulates antibody-mediated cellular toxicity, allowing the body s own immune system to help eliminate the neoplastic cells. In the first prospective, randomized, double-blind, placebo-controlled trial utilizing this antibody combined with a single 4 week cycle of the L-CHOP protocol, the proliferation-free interval and overall survival time were nearly three times higher in dogs that received the antibody compared to (Continued on page 4)

4 those that received L-CHOP alone, with the most significant effect being seen in the duration of the second remission. Toxicity was mild and restricted to the effects of the L-CHOP arm of treatment. Aratana Therapeutics will be marketing the antibody---the cost has yet to be determined but is anticipated to be equivalent to the cost of the full L-CHOP protocol. While the antibody has efficacy as a single-agent therapy, remission and survival times are longer when combined with more traditional chemotherapy drugs. The optimal chemotherapy to combine it with has yet to be identified, but this determination will have to take into account not only optimized survival times, but also the realities of the average dog owner s financial constraints. The second monoclonal antibody is anti- CD52, and thus directed against canine T-cell lymphomas, has received first conditional licensure and is slated for release shortly after the B-cell antibody this year. From the general and specialty practice perspectives, the development and commercial release of these antibodies makes it more important than ever before to fully classify the types of lymphoma present in our patients, so flow cytometry prior to any treatment should be considered wherever owner finances allow. Anti-lymphoma antibodies are not the only expanding areas of immunotherapy in veterinary oncology. Promising work is being done in advancing the development of anti-tumor vaccines against a variety of cancer types, as well as the use of apheresis to remove soluble defense receptors/factors produced by many tumors that would ultimately sensitize these tumors to the body s natural immune responses. With more and more owners being willing to explore more aggressive treatments for their pets with cancer, it is critical to stay abreast of the recent developments so they we can guide them in their treatment decisions. Podell, M. "Highs and Lows of Medical Marijuana in the Treatment of Epilepsy." ACVIM Forum Indiana, Indianapolis. 04 June Lecture. Ogilvie, G. "Role of Chemoimmunotherapy for Canine Lymphoma." ACVIM Forum Indiana, Indianapolis. 05 June Lecture. Benson, K. Pharmacodynamics of Transdermal Mirtazapine in Healthy Client-owned Cats. ACVIM Forum June Raw data. Indianapolis, Indiana. Quimby, J. Pharmacokinetics and Pharmacodynamics of Transdermal Mirtazapine in Purpose-bred Cats. AC- VIM Forum June Raw data. Indianapolis, Indiana. Photos courtesy of Google images.

5 Internal Medicine Kelly Akol, DVM, DACVIM (SAIM) Merrianne Burtch, DVM, DACVIM(SAIM) Michelle Pressel, DVM, DACVIM (SAIM) Bryn Hoffman, MVB (Residency Trained in Internal Medicine) Surgery Lisa Metelman, MS, DVM, DACVS Tom LaHue, DVM, DACVS Critical Care Colleen Brady, DVM, DACVECC Lillian Good, DVM, DACVECC Cardiology Kristine Chan, DVM, DACVIM(Cardiology) Our Doctors Radiology (VRS) Larry Kerr, DVM, DACVR Mark Lee, DVM, DACVR Emergency Christian Robison, DVM Mark Saphir, DVM Jessica Kurek, DVM Sara Heidelberger, DVM Behavior Jan Brennan, DVM (practice limited to behavior) About Our Hospitals Pacific Veterinary Specialists was founded to provide high quality, specialized medical care to companion animal patients. Our practice is dedicated to serving the veterinary community as a partner in total patient care. We offer comprehensive specialized services including video endoscopy, Doppler ultrasound, surgery, 24-hour ICU care, and emergency and critical care. Our staff is committed to providing compassionate and thorough medical care that meets the needs of the patient, client, and referring veterinarian. In September 2011 we opened PVSM and currently offer internal medicine appointments and same day referrals, Tuesday through Thursday in Monterey. Behavior consultations by appointment are available on Mondays. Pacific Veterinary Specialists PLEASE PLACE STAMP HERE st Avenue