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Validated capillary electrophoresis method for the determination of atropine and scopolamine derivatives in pharmaceutical formulations.

The simultaneous determination of atropine and scopolamine derivatives, which have similar structures, was investigated by using capillary zone electrophoresis. The effects of buffer pH, buffer concentration and hydroxypropyl-beta-cyclodextrin concentration on migration time and resolution of the investigated compounds were systematically studied. The selected electrophoretic buffer consisted of a 80 mM sodium citrate pH 2.5, containing 2.5 mM hydroxypropyl-beta-cyclodextrin as the complexing agent. Quantitative analysis was validated by testing the reproducibility of the method, giving a relative standard deviation less than 1 and 2% for the intermediate precision of migration times and peak area ratios, respectively. The linearity of the method was assessed between 50 and 150% of the theoretical content (coefficient of correlation greater than 0.99). The proposed method was found to be suitable and accurate for the determination of these basic drugs in pharmaceutical preparations.

2-Hydroxypropyl-beta-cyclodextrin↗

Effect of oxitropium bromide (Ba253) on isolated respiratory smooth muscle and release of chemical mediators from passively sensitized lung fragments.

The effect of oxitropium bromide (Ba253), a quaternary scopolamine derivative, on the resting tonus and agonist-induced contraction of isolated guinea pig airway smooth muscle and on the anaphylactic release of histamine and immunoreactive leukotrienes (i-LTs) from lung fragments were investigated and compared with those of Sch1000, atropine and isoproterenol. Ba253 dose-dependently inhibited the acetylcholine (ACh)-induced contraction of the isolated trachea and lung parenchyma. The degree of inhibitory potency was similar to that of Sch1000 and 10 times higher than that of atropine. Ba253 minimally influenced the resting tonus or contractions induced by other agonists including histamine, serotonin and LTD4. Sch1000 and atropine had similar or slightly stronger inhibitory effects on the tonus and contractions than Ba253. On the other hand, low concentrations of isoproterenol solely relaxed the resting tonus and inhibited the the agonist-induced contractions of both preparations. Neither Ba253 nor Sch1000 inhibited the anaphylactic release of histamine and LTs from both guinea pig and human lung fragments, but both mediator releases from either species were slightly inhibited with dose-dependency by atropine and potently inhibited by isoproterenol. From these results, it is suggested that Ba253 is a relatively specific antagonist to cholinergic receptors and might be possibly effective as an inhalant for asthma.

Animals↗

Determination of the enantiomeric purity of scopolamine isolated from plant extract using achiral/chiral coupled column chromatography.

The optical purity of scopolamine derived from Datura sanguinea was determined using coupled column chromatography. A C18 column was used to separate scopolamine from the additional alkaloids and other biological material present in the vegetal extract. The C18 column was coupled through a six-port switching valve to two beta-cyclodextrin columns in series which were used to resolve the scopolamine enantiomers. A single acetylated beta-cyclodextrin column gives equivalent results to the native cyclodextrin columns because of slightly higher enantioselectivity for scopolamine. A multistep extraction procedure is used to isolate scopolamine from the vegetal material. 4-6% of the scopolamine in the final extract was found to be the d enantiomer. Sample extracts as well as commercial scopolamine hydrobromide were treated under various conditions commonly encountered during typical commercial extraction procedures and analyzed in order to determine if the d enantiomer was present in the original material or if it was produced during the extraction process and, if so, determine which step and conditions contribute to racemization. Both the salt and the extract were found to be susceptible to racemization under basic conditions (greater than or equal to pH 9) although the extract appeared to be more susceptible than the salt. Tropic acid formed from the hydrolysis of scopolamine seemed to be completely racemized even though the remaining scopolamine was only partially racemized. Within experimental error, no d enantiomer was found in the original fresh plant material.

Acetylation↗

Effects of paeoniflorin derivatives on scopolamine-induced amnesia using a passive avoidance task in mice; structure-activity relationship.

Paeoniflorin (1) and its derivatives having in common a cage-like pinane skeleton with hemiketal-acetal system, were evaluated for their effects on memory impairment induced by scopolamine in mice using a step-down type passive avoidance task. In the test session, 1 and its derivatives were intraperitoneally (i.p.) administered at doses of 0.002, 0.01, 0.02 and 0.2 mmol/kg, and 30 min later (15 min before the experiment), scopolamine (1 mg/kg, i.p.) was given. These compounds showed dose-dependent attenuation in a dose range of 0.002-0.02 mmol/kg and also enhancement of scopolamine-induced decrease in step-down latency. The effects of these compounds, except that of 2',3',4',5'-O-tetraacetyl-3-O-methylpaeoniflorin (8), followed a bell-shaped dose response profile. 8-Debenzoyl-6-deglucosyl-3-O-methylpaeoniflorin (6) showed no significant increase in the step-down latency at all tested doses. Maximum step-down latency was obtained by 3-O-methylpaeoniflorin (3) and 2',3,3',4',5'-penta-O-methylpaeoniflorin (7) (the minimal effective dose was 0.002 mmol/kg). Relative to 3, debenzoylation, as in 8-debenzoyl-3-O-methylpaeoniflorin (4), slightly increased the latency, while deglucosylation, as in 6-deglucosyl-3-O-methylpaeoniflorin (5), significantly reduced the prolongation of latency. Removal of both glucose and benzoyl moieties resulted in the loss of activity as seen in 6. These results revealed that, in addition to the cage-like pinane skeleton, the benzoyl and the glucosyl moieties are important structural elements of the paeoniflorin skeleton as its effects on scopolamine-induced amnesia.

Amnesia↗

Scopolamine prevents augmentation of stereotypy induced by chronic methamphetamine treatment.

Cholinergic neurotransmission has been implicated in various forms of neural plasticity such as kindling and learning. We have previously shown that blockade of muscarinic cholinergic receptors prevents the development of locomotor sensitization to methamphetamine. The present study was conducted to examine whether scopolamine, a muscarinic cholinergic antagonist, would also block augmentation of stereotypy induced by chronic methamphetamine (MA) treatment. Rats treated with MA (2.5 mg/kg, SC) for 10 days indicated significantly enhanced stereotyped behavior when tested with MA (2.5 mg/kg) after a 7- to 8- day withdrawal. Pretreatment with scopolamine (3 mg/kg) prior to MA administration prevented the augmentation of stereotypy. Rats treated with scopolamine alone showed no difference in MA-induced stereotypy compared to those treated with saline. Scopolamine methylbromide, a derivative of scopolamine that does not easily cross the blood-brain barrier, had no effect on the augmentation of stereotypy. These results suggest that stimulation of central muscarinic cholinergic receptors plays a role in the development of sensitization to the stereotypy stimulating effect of methamphetamine.

Animals↗

Unit-dose assay of tropine alkaloids and their synthetic analogs.

A charge-transfer spectrophotometric method was developed for unit-dose assay of the tropine alkaloids and some of their synthetic analogs. The high molar absorptivities of the charge-transfer bands of the alkaloids with iodine in ethylene dichloride resulted in improved recoveries and good precision, particularly at the low dose levels of pediatric and hypodermic tablets.

Atropine↗

Titrating matching-to-sample performance in pigeons: effects of diazepam, morphine, and cholinergic agents.

Five adult, male White Carneau pigeons were trained to respond under a titrating matching-to-sample schedule of reinforcement. Under this titration schedule, each trial began with the presentation of a sample stimulus (red or green light) on the center key of a three-key pigeon chamber. Completion of 15 responses on the center key resulted in the termination of the stimulus presentation and the initiation of a delay period. The length of the delay changed as a function of the pigeon's performance. During the first five trials of each session, the delay was fixed at 3 s in length. On the sixth and all subsequent trials, the length of the delay was either increased, did not change, or decreased such that accuracy was maintained at approximately 80%. Following the delay, two of the three pigeon keys were transilluminated with different colored lights (red or green). A single response upon the key transilluminated with the same stimulus color as the sample stimulus resulted in the presentation of food. A response on the key transilluminated with the stimulus color that did not match the sample stimulus resulted in a time-out period. Using this procedure, the effects of two drugs of abuse, diazepam (0.03-3 mg/kg) and morphine (0.03-10 mg/kg), a muscarinic antagonist, scopolamine (0.003-0.3 mg/kg), the quaternary derivative of scopolamine, methylscopolamine (0.003-0.3 mg/kg), a cholinesterase inhibitor, physostigmine (0.003-0.1 mg/kg), and the quaternary derivative of physostigmine, neostigmine (0.003-0.1 mg/kg), were determined. Diazepam decreased matching accuracy such that a decrease in the mean delay value for the session was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Antagonism of central but not peripheral cholinergic receptors retards amygdala kindling in rats.

The effects of antagonism of muscarinic cholinergic receptors on the development of seizures produced by electrical stimulation of the amygdala (kindling) were assessed in three experiments. Rats pretreated with the muscarinic antagonist scopolamine developed seizures more slowly than did untreated rats. Whereas scopolamine retarded the development of seizures in a dose-dependent manner, it did not affect the intensity or duration of seizures when administered to kindled control rats. Pretreatment with methylscopolamine, a quaternary derivative of scopolamine that does not readily cross the blood-brain barrier, did not affect the rate of development of seizures, nor did it affect established seizures. Thus the prophylactic effects of scopolamine are produced in the central nervous system and not in the periphery. The results from these experiments are consistent with the idea that central cholinergic or cholinoceptive neurons are critically involved in amygdala kindling.

Amygdala↗

Anticholinergic drugs in airways obstruction.

This paper reviews briefly the place of ipratropium bromide in the treatment of airways obstruction. Oxitropium bromide, a new quaternary ammonium compound derived from scopolamine was shown to be as effective a bronchodilator in a dose of 200 micrograms by inhalation as ipratropium bromide 80 micrograms in 20 patients with atopic asthma.

Asthma↗