Alfa2 Antagonistlerinin Küçük Ruminantlarda Kullanımı Üzerine Bir Derleme

Abstract

SummaryIn recent years, alpha 2 agonists are the most widely used as sedative and analgesic drugs in veterinary medicine because of several useful properties like fast onset, reversibility and analgesia. Alpha 2 agonists produce different actions by binding to their corresponding receptor subtypes located on various parts of the central nervous system. Ruminants are especially sensitive to alpha 2 agonists due to the distribution of the specific alpha 2 adrenoceptor subtypes, compared with other species. In ruminants, alpha 2 agonists are generally used as sedatives and analgesics for restraint, clinical diagnosis, and minor surgeries. Clinical experiments indicated that analgesia does not exist throughout the period of sedation, so these agents alone are not sufficient for painful or major surgical procedure. Epidural administration of alpha 2 agonists produced potent analgesia with minimal sedative or cardiovascular effects, and considered one of the most reliable techniques in ruminant. Alpha 2 agonists also used as a preanesthetic medication and have been obviously anesthetic sparing effects. They causes some unwanted effects, such as excessive saliva, bradycardia, depressed respiratory rate, decreased rectal temperature, hyperglycemia, uterine contractions and decreased ruminal and intestinal motility. These side effects are influenced by the doses and administration routes of alpha 2 agonists, and their selectivity to alpha 2 adrenoceptor subtypes. Attentions should be taken to avoid the use of these agents in sick patients, while careful monitoring of the patient condition is always mandatory after receiving these agents. Fortunately, the availability of specific antagonists assures the uses of alpha 2 agonists in ruminants. For the safety, an appropriate low dose of alpha 2 agonists is always recommended in ruminants. Keywords ÖzetSon yıllarda alfa 2 antagonistleri çabuk etki, geridönüşebilirlilik ve analji gibi bazı özellikleri nedeniyle veteriner hekimlikte sedatif ve analjezik olarak en yaygın kullanılan ilaçlardır. Alfa 2 antagonistleri merkezi sinir sisteminin çeşitli bölgelerinde yer alan ilişkili reseptörlere bağlanmak suretiyle değişik reaksiyonlara neden olur. Ruminantlar diğer türlerle karşılaştırıldığında spesifik alfa 2 adenoreseptör subtipleri nedeniyle alfa 2 antagonistlerine karşı özellikle sensitiflerdir. Ruminantlarda alfa 2 antagonistleri genel olarak zapturapt, klinik tanı ve küçük cerrahiler amacıyla sedatif ve analjezik olarak kullanılır. Klinik deneyler analjezinin sedasyonun süresinin tümü boyunca mevcut olmadığını göstermektedir. Bu nedenle bu maddeler acılı veya büyük cerrahi müdahalelerde tek başlarına yeterli değillerdir. Alfa 2 antagonistlerinin epidural uygulanması minimal sedatif veya kardiyovasküler etkiler ile birlikte muhtemel analjezi üretmektedir. Bu uygulama ayrıca ruminantlarda en güvenilir teknik olarak kabul edilmektedir. Alfa 2 antagonistleri ayrıca preanastetik uygulama olarak da kullanılmaktadır ve bariz olarak anestetik ajanın az kullanımının sağlayıcı etkileri...

Cardiorespiratory and hemogasometric effects of epidural ketamine and its associations with morphine and xylazine in sheep

“…Studies on dairy cows that evaluated behavioral changes in animals under various milking conditions concluded that, when managed by unknown people and in unusual environments, the animals showed increased HRs, among other behavioral changes (Munksgaard, Depassillé, Rushen, Herskin, & Kristensen, 2001). The low HR in the G KX group was expected, as xylazine may induce cardiac depression through a number of mechanisms, such as central nervous system sympathetic outflow reduction, the direct depression of the pacemaker and cardiac conduction, the inhibition of norepinephrine release from sympathetic terminals, and the increase of acetylcholine release by cardiac parasympathetic nerves (Shah et al, 2014). There was no change in blood pressure, which supports the idea that the effects on the cardiovascular system were minimal.…”

“…α 2 -Agonists tend to promote an initial pressure increase through peripheral vasoconstriction, mediated by stimulation of the α 2 receptors of the vascular smooth musculature, followed by hypotension via baroreceptor reflex and sympathetic tone reduction. When administered intravenously, xylazine can lead to an initial 26% increase in mean arterial pressure, while intramuscular injections lead to an 18% increase (Shah et al, 2014). Epidural administration and the subsequent slow absorption into the systemic circulation, in addition to the low dose used, prevented these effects.…”

“…Besides its effect as a potent muscular relaxant, it is used in epidural analgesia as it interacts with α 2 receptors in descending pathways, at both the spinal and supraspinal levels (Guirro et al, 2011). Some of the possible undesirable effects of xylazine include respiratory depression, pulmonary edema, hypercapnia, transient arterial hypertension, hypotension, and bradycardia; these effects are dose dependent and most frequently observed after intravenous injections (Shah, Ding, & Hu, 2014). Opioids are widely used in several species during the perianesthetic period and in severe pain management because of the analgesic effects of their interactions with µ and K receptors.…”

Beyaz Yeni Zelanda Tavşanlarında Vitamin C Premedikasyonu Sonrasında Ksilazin-Ketamin Anestezisi

“…Body temperature is expected to decline following the anesthesia by reduction of muscular activity and depression of thermoregulatory center [22] . In our study, however, xylazine-ketamine anesthesia, with our without vitamin C premedication, did not significantly reduce the body temperature.…”

Tendencies and perspectives of central alpha2-adrenomimetic application in medicobiological research

“…When used in therapeutic doses highly selective drugs possess the greatest activity and safety. It is reported that the selectivity ratio between the α2/α1 subtypes of the drugs is the following: medetomidine (1620/1), detomidine (260/1), clonidine (220/1), xylazine (160/1) [13].…”