Xylazine
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| Non-proprietary name | Xylazine | |||||||||||||||||||||
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2- (2,6-Dimethylphenylamino) -5,6-dihydro-4 H -thiazine |
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| Molecular formula | C 12 H 16 N 2 S | |||||||||||||||||||||
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| Molar mass | 220.33 g mol −1 | |||||||||||||||||||||
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well soluble in dilute acids, benzene, acetone and chloroform, but almost insoluble in water and basic solutions |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||||||||||||||
Xylazine is a drug that is widely used in veterinary medicine . It is used as a tranquilizer ( sedative ), pain reliever ( analgesic ) and to relax the skeletal muscles ( muscle relaxant ).
Xylazine is approved for most domestic , farm and laboratory animals in the German-speaking area . The substance from the class of thiazinamines is similar in chemical properties and pharmacological effects to clonidine, which is used as a blood pressure lowering agent in human medicine .
chemistry
Xylazine is used in veterinary medicine as xylazine hydrochloride ( molecular formula C 12 H 16 N 2 SHCl, molar mass 256.80 g · mol −1 , CAS number 23076-35-9). The xylazine hydrochloride solution is odorless and almost tasteless and has a pH value of 5.5.
The LD 50 in cats is 25 mg kg −1 after intravenous administration and 40 mg kg −1 after intramuscular administration . That's about 20 times the recommended dose.
Mechanism of action
Xylazine acts as central and peripheral α 2 adrenoceptor - agonist . The plasma half-life is 1 to 6 minutes. The Ver stoffwechselung takes place in the liver , excretion to 70% via the kidneys and 30% via the bile .
The active ingredient causes pronounced sedation and hypnosis for about 30 minutes. It is most pronounced in ruminants . Pigs are the least sensitive, so sedation only occurs when the doses are lethal. In addition, xylazine can also have an anti-anxiety effect regardless of its sedating properties .
The analgesic effect ( analgesia ) is also different depending on the species and lasts about 20 minutes. It is between a fifth and the full effect of morphine , in the case of abdominal pain ( colic ) the effectiveness in horses even exceeds that of morphine. On the other hand, the analgesic effect on the limbs in horses and cattle is inadequate for surgical interventions.
The central muscle relaxing effect of xylazine is rather minor and comparable to that of chlordiazepoxide .
The effects on blood circulation are time-dependent. Initially, for about 15 minutes, the stimulation of the peripheral α 2 -adrenoceptors leads to an increase in blood pressure and a decreased heart rate . Subsequently, the predominant effect on the central α 2 -adrenoceptors in the circulatory center leads to reduced sympathetic activity and thus to a sustained drop in blood pressure and reduced excitability of the heart, which can be counteracted by atropine .
Finally, xylazine also has a local anesthetic effect that is greater than that of procaine , but is not exploited in veterinary practice.
Application & Abuse
Xylazine is commonly given as an intramuscular or intravenous injection to induce sedation and analgesia for examinations and treatments. It is very often combined with ketamine ( Hellabrunner mixture ) or with ketamine and guaifenesin ( Triple-Drip ) to produce an injection anesthetic . These combinations are suitable for performing painful procedures and operations.
In cats, the active ingredient is also used as an emetic , the success rate is around 50%.
Since around 2005, xylazine, originally distributed as a drug in Puerto Rico , has been in circulation in the United States as a common street drug, mostly as an additive, with the corresponding side effects .
Side effects
For intramuscular or subcutaneous injection , there may be occasional low-grade temporary tissue damage.
As a side effect of xylazine decreases after an initial increase in blood pressure in the course through its vasodilating effect the blood pressure and can also be bradycardia lead. In horses, 2nd degree AV block can occur for 1–3 minutes .
A more frequent side effect are states of excitement ("Rompun roar" in cattle).
In cattle there is an increase in body temperature ( hyperthermia ), while in other animals it falls due to the disruption of thermoregulation . In ruminants , xylazine leads to excessive salivation, which creates the risk of aspiration pneumonia , which can be reversed by atropine. In other animal species, however, xylazine inhibits the flow of saliva. In dogs and especially in cats, xylazine also stimulates the vomiting center , so that the active ingredient can also be used as an emetic . Xylazine has a respiratory depressive effect, especially in cattle. In ruminants can by inhibiting rumen motor skills a Pansentympanie occur. In cattle, a drop in insulin level and thus an increase in blood sugar level ( hyperglycaemia ) has also been observed. In addition, xylazine inhibits the release of ocytocin and the flow of milk in a dose-dependent manner , which is why the active ingredient should not be used immediately before milking.
Sudden deaths can occur in dogs 3–4 hours after use.
In pregnant cattle xylazine, by stimulation of the α-receptors in the last trimester of pregnancy uterine a premature birth trigger.
Contraindications
Contraindications to the use of xylazine are heart problems of all kinds, a lack of blood volume , dehydration , diabetes , kidney and liver damage , traumatic brain injury and epilepsy . In ruminants , it may not be used in the last third of gestation because of its induction effect . Use of the drug for anesthesia from ASA group III is generally not recommended.
When using the anti- parasitic drug Amitraz , xylazine must not be used due to synergetic effects.
Antagonists
The effect of Xylazine can be explained by the use of adrenergic receptor antagonists such as atipamezole , Tolazolin and yohimbine cancel .
Trade names
Narcoxyl, Rompun, Xylasol, numerous generics
See also
literature
- Wolfgang Löscher et al. (Ed.): Pharmacotherapy for pets and farm animals . 7th completely revised and expanded edition. Paul Parey Verlag, Stuttgart 2006, ISBN 3-8304-4160-6 .
- Patent US4614798 : (synthesis).
Individual evidence
- ↑ entry for Xylazine at Vetpharm, accessed on 21 November 2011th
- ↑ a b c Xylazine data sheet from Sigma-Aldrich , accessed on October 23, 2016 ( PDF ).
- ↑ Thawley VJ, Drobatz KJ. Assessment of dexmedetomidine and other agents for emesis induction in cats: 43 cases (2009-2014). In: J Am Vet Med Assoc. 2015; 247 (12): 1415-1418.
- ↑ JC Reyes, JL Negrón, HM Colón, AM Padilla, MY Millán, TD Matos, RR Robles: The Emerging of Xylazine as a New Drug of Abuse and its Health Consequences among Drug Users in Puerto Rico . In: Journal of Urban Health . 89, No. 3, March 6, 2012, pp. 519-526. doi : 10.1007 / s11524-011-9662-6 . PMID 22391983 . PMC PMC3368046 (free full text). Retrieved July 10, 2020.
- ↑ Luz Silva-Torres, Christian Veléz, Lyvia Álvarez, Beatriz Zayas: Xylazine as a Drug of Abuse and Its Effects on the Generation of Reactive Species and DNA Damage on Human Umbilical Vein Endothelial Cells . In: Journal of Toxicology . 2014, November 11, 2014. doi : 10.1155 / 2014/492609 . Retrieved July 10, 2020.
- ↑ Stella Wong, John Curtis, William Wingert: Xylazine as a Drug of Abuse and Its Effects on the Generation of Reactive Species and DNA Damage on Human Umbilical Vein Endothelial Cells . In: Journal of Forensic Sciences . 53, No. 2, Feb. 14, 2008, pp. 495-498. doi : 10.1155 / 2014/492609 . PMID 18284526 . Retrieved July 10, 2020.
