Neuropharmacology. 1983 Feb;22(2):249-52.
Cyclobenzaprine [Flexeril] effects on locus coeruleus cells in tissue slice.

Lang IM, Barnes CD.

Tissue slices 400 mu thick were taken from the brain stem, at the level of the locus coeruleus, of 150-250 g Sprague-Dawley rats. Microelectrodes were placed in the locus coeruleus under visual control, and a cell whose discharge rate would decrease with microiontophoretic application of norepinephrine or clonidine was sought. Cyclobenzaprine [Flexeril] (CBZ) was then introduced into the perfusion medium at a concentration equivalent to 1 mg/kg body weight of the whole animal. Discharge rates before and during CBZ administration were compared. The six cells with initial discharge rates between 2 and 10 Hz decreased firing with CBZ, whereas the four cells with initial rates between 0.5 and 1.5 Hz increased their rates with CBZ.

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J Pharm Sci. 1982 Jun;71(6):656-8.
Determination of cyclobenzaprine in tablets by high-performance liquid chromatography.

Heinitz ML.

A convenient high-performance liquid chromatographic method for the quantitative determination of cyclobenzaprine hydrochloride in tablets is described. Samples were dissolved in 0.05 N sulfuric acid and diluted with methanol. The cyclobenzaprine hydrochloride was chromatographed using an octylsilane column and the eluent acetonitrile-0.6% dibasic potassium phosphate aqueous buffer (pH 3.0) (75:25) at a flow rate of 1.5 ml/min. Naphazoline hydrochloride was used as an internal standard. The UV detector response at 254 nm was linear for cyclobenzaprine hydrochloride in the 0.005-0.03 mg/ml range under conditions of the analysis.

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Neurotoxicology. 1981 Dec;2(4):703-9.
Ocular aldehyde dehydrogenase in rodents.

Messiha FS.

The presence of NAD-dependent ocular aldehyde dehydrogenase in rodents is reported. The enzyme is species and strain-dependent. Ocular ALDH possesses a significantly greater specific activity than that of the hepatic tissue of the species studied. d-Amphetamine non-competitively inhibited rat eye ALDH in vitro. Short-term administration of cyclobenzaprine, a tricyclic compound with muscle relaxant property, induced ocular aldehyde dehydrogenase. This is compared with lack of effect of certain CNS-stimulants, ethanol intake and of a monoamine oxidase inhibitor on endogenous ALDH in vivo.

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Can J Physiol Pharmacol. 1981 Jan;59(1):37-44.
Cyclobenzaprine: a possible mechanism of action for its muscle relaxant effect.

Commissiong JW, Karoum F, Reiffenstein RJ, Neff NH.

Intravenously administered cyclobenzaprine (CBZ) (Flexeril), a clinically used, centrally acting muscle relaxant, abolished muscle rigidity in the intercollicular decerebrate rat. In animals in which the locus coeruleus was lesioned bilaterally previously, CBZ failed to attenuate the electromyogram. In the ventral horn of the cord, which receives a dense noradrenergic innervation from the locus coeruleus, CBZ caused an increase in the metabolism of noradrenaline. In the zona intermedia of the thoracic cord, which is not innervated by the locus coeruleus, CBZ caused only minimal effects on noradrenaline metabolism. Cells in the locus coeruleus were activated by CBZ. The results indicate that in the intercollicular decerebrate rat, an intact, coerulospinal, noradrenergic projection is essential for the muscle relaxant effect of CBZ. Muscle relaxation apparently results from an activation of locus coeruleus neurones, leading to an increased release of noradrenaline in the ventral horn of the cord and the subsequent inhibitory action of noradrenaline on alpha motoneurones.

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J Med Chem. 1980 Nov;23(11):1255-8.
Antiarrhythmic activity of amitriptyline analogues in conscious dogs after myocardial infarction: cyproheptadinium methiodide.

Wilkerson RD, Henderson JD.

The antiarrhythmic effects of amitriptyline (1), its secondary amine metabolite nortriptyline (2), as well as cyclobenzaprine (3) and cyproheptadine (4), tertiary amine analogues of 1, were studied in conscious dogs 24 h after myocardial infarction. Since the sedative side effect of 4 presents a potential problem for its clinical use, a quarternary derivative of 4, cyproheptadine methiodide (5), was prepared and its effects also studied in this model. Complete conversion to a normal sinus rhythm occurred in all animals studied after cumulative doses of 1700 micrograms/kg (6.17 mumol/kg) of 3, 1300 micrograms/kg (4.69 mumol/kg) of 1, 300 micrograms/kg (1.04 mumol/kg) of 4, and 25 micrograms/kg (0.058 mumol/kg) of 5. While 2 significantly decreased ventricular ectopic activity, it did not convert any of the animals studied to a sinus rhythm at doses up to 3000 micrograms/kg. Thus, the order of potency for conversion to a normal sinus rhythm appears to be 5 >> 4 > 1 > 3 >> 2. These data suggest that 5 is very potent in converting ventricular arrhythmias associated wtih myocardial infarction.

Online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7452678&dopt=Abstract cyclobenzaprine Flexeril