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Sedation and Restraint for Standing Procedures
Published in Michele Barletta, Jane Quandt, Rachel Reed, Equine Anesthesia and Pain Management, 2023
Antagonism. These agents can be antagonized by alpha-2 adrenoreceptor antagonists. When the antagonist is administered IV, it should be injected slowly to avoid adverse effects (excitatory awakening, pain, hypotension, and arrhythmias).Atipamezole (0.05–0.2 mg/kg IM or slow IV). Most selective for alpha-2 receptor antagonism, avoiding unwanted effects of alpha-1 antagonism, including profound hypotension.Yohimbine (0.04–0.15 mg/kg IM or slow IV). Mildly selective for alpha-2 receptors.Tolazoline (0.5–4.0 mg/kg IM or slow IV). Not selective.
Tolazoline
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
Tolazoline is a non-selective competitive a-adrenergic receptor antagonist with vasodilator activity. It is or most likely was used in treatment of persistent pulmonary hypertension of the newborn and was also used to treat spasms of peripheral blood vessels, e.g. in acrocyanosis. Topically, it was used for ophthalmologic indications such as circulatory changes of the retina, chorioid and optic tract, caustic trauma and degenerative changes of the cornea and as an adjunct in the treatment of various inflammatory corneal affections. Products containing tolazoline were withdrawn from the U.S. market by the (or a) producer in 2002. The drug is however used in veterinary medicine, to reverse xylazine-induced sedation in horses. In pharmaceutical products (mostly veterinarian), tolazoline is employed as tolazoline hydrochloride (CAS number 59-97-2, EC number 200-447-3, molecular formula C10H13CIN2) (1).
Adrenoceptor Antagonists
Published in Kenneth J. Broadley, Autonomic Pharmacology, 2017
Phentolamine (RogitineUK, RegitineUS) and tolazoline (Priscoline, no longer available) are competitive α-adrenoceptor antagonists with no selectivity for the α1- or α2-subtypes (Table 5.2). They are structurally related to the imidazoline α-adrenoceptor agonists (Table 4.3) and tolazoline has partial agonist activity. They have poor specificity for α-adrenoceptors and display a wide range of activity at other sites. For example, phentolamine blocks 5-HT receptors (Doggrell 1992) and stimulates histamine release from mast cells. They both stimulate the gut to cause diarrhoea and also stimulate the secretion of saliva, sweat and lacrymal secretions. These effects are blocked by atropine and are therefore mediated via muscarinic receptors, possibly through inhibition of cholinesterase. They also enhance gastric acid secretion, an effect similar to that of histamine to which they are closely related structurally. Another histamine-like effect is vasodilatation, which occurs independently of blockade of α-adrenoceptors and which contributes to the fall in blood pressure. Generally, the side effects are less pronounced with phentolamine than with tolazoline, the latter having become largely obsolete.
Treatment of amblyopia: part 4
Published in Strabismus, 2019
This consists of retrobulbar injections of 2–4% saline or Priscol-NaCl (NaCl 4%, Priscol (tolazoline) solution aa 0.5), daily pilocarpine instillation for a very long time and a vitamin-rich diet with periodic additional vitamin administration. Injection treatment comprises 10–12 retrobulbar injections, the first with 2% and the remaining with 4%. Since especially the macula suffers damage in myopia, a significant influence is only possible with injections near the macula. With proper anesthesia, the completely painless injections can be carried out in 8–10 year old children without difficulty. Amblyopia in myopia rarely occurs before treatment, because it usually only appears more strongly during the growth period in the second to fourth year of training. The retrobulbar injections are very important in myopia with changes of the retina. Usually, one course is sufficient for a year or more. In most cases that aggravate a few additional injections will suffice. The injections do not succeed in preventing the increase in myopia but diminish it and, above all, counteract the unfavorable effect on the macula associated with growth. As our statistics show, the combination of injections and exercises represents one of the most gratifying treatments.
Non-occlusive mesenteric ischemia: two case reports and a short review of the literature
Published in Acta Chirurgica Belgica, 2018
Georges Versyck, Charles de Gheldere, Patrick Vanclooster
Intra-arterial administration of papaverine in the mesenteric blood vessels is only used when NOMI is diagnosed with mesenteric angiography. Papaverine is a phosphodiesterase inhibitor which relaxes vascular smooth muscle cells. A 60 mg bolus is followed by a constant infusion of 30-60 mg per hour through the mesenteric catheter [25]. Systemic adverse effects are rare because papaverine has a high first pass metabolism. Other local vasodilators include prostaglandine E1, tolazoline and laevodosine [8,20].
Trace amine associated receptor 1 (TAAR1) modulators: a patent review (2010-present)
Published in Expert Opinion on Therapeutic Patents, 2020
Michele Tonelli, Elena Cichero
Preliminary repositioning strategies on adrenoreceptor and dopaminergic ligands allowed to identify aryloxypropylamine-containing compounds as TAAR1 agonists featuring higher potency toward the murine receptor over the rat orthologue [15]. Conversely, the selection of the (2-benzyl)imidazoline-containing ring experienced by naphazoline and tolazoline, disclosed for the first time, adequate affinity values toward the human TAAR1 receptor, in the micromolar range [16].