Stability-Indicating UPLC and TLC-Densitometric Methods for Determination of Benztropine Mesylate and Its Carcinogenic Degradation Product.

Two accurate, precise and highly selective stability-indicating methods were adopted for simultaneous determination of benztropine mesylate (BNZ) in presence of its hepatotoxic and carcinogenic degradation product, benzophenone (BPH) either in pure form or in the pharmaceutical formulation without any preliminary separation steps. The first method is a thin layer chromatography (TLC)-densitometric method that depended on separation of BNZ from its degradate on TLC aluminum plates precoated with silica gel 60 F254 as the stationary phase using a developing system consisted of hexane:methylene chloride:triethylamine (5:5:0.6, by volume) and scanning the separated bands at 235 nm. Linear regression analysis data for the calibration plots of BNZ and BPH showed perfect linear relationships over the concentration range of 1.5-10 and 1-10 µg band-1, respectively. The second method is (UPLC) method, at which the mixture was separated on a reversed phase C8 analytical column (1.9 µm ps, 50 mm × 2.1 i.d.) using a mobile phase of acetonitrile: aqueous sodium dodecyl sulfate (50:50, v/v) Adjusted to pH = 3 with phosphoric acid, at a flow rate of 0.5 mL min-1. Quantification was achieved at 210 nm based on peak area and linear calibration curves over the concentration ranges of (20-200 µg mL-1) and (5-50 µg mL-1) for BNZ and BPH, respectively, were obtained. The investigated methods were successfully applied to available dosage form and method validation has been carried out. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by reported one and no significant differences were obtained regarding both accuracy and precision.

Acute benztropine intoxication and fatality.

A woman was found unresponsive with an empty bottle of Cogentin(®) prescribed to another. Admitted to an area hospital, her condition steadily declined until death 29 h after admission. Following toxicological screening on hospital (admission) whole blood, the only significant compound detected was benztropine. Benztropine was confirmed at 0.28 mg/L - the highest antemortem blood concentration recorded in a case of toxicity or fatality uniquely associated with benztropine. A second serum antemortem specimen showed a benztropine concentration of 0.19 mg/L. Despite over 24 h in the hospital, benztropine was also found in the postmortem specimens collected at autopsy. Peripheral blood, central blood, liver, and gastric concentrations were 0.47 mg/L, 0.36 mg/L, 9.6 mg/kg, and 44 mg, respectively. These results indicate that benztropine exhibited a potential difference between whole-blood and serum (plasma) concentrations. Additionally, in consideration of literature data, benztropine was found indicative of a compound prone to at least some postmortem redistribution.

Investigation of the potential pharmacokinetic and pharmaco-dynamic drug interaction between AHN 1-055, a potent benztropine analog used for cocaine abuse, and cocaine after dosing in rats using intracerebral microdialysis.

PURPOSE: AHN 1-055, a benztropine (BZT) analog, binds with high affinity to the dopamine transporter (DAT), possesses behavioral, pharmacokinetic (PK) and brain microdialysate dopamine (DA) profiles distinct from cocaine. Accordingly, the objectives of this study were to evaluate the pharmacokinetics and dopamine release of AHN 1-055, in the presence of cocaine. METHODS: Male Sprague Dawley rats ( approximately 300 g) were administered 5 mg/kg of AHN 1-055 and cocaine i.v. and blood and brain samples were collected over 36 h. In addition, dialysis probes were stereotaxically implanted into the nucleus accumbens and extracellular fluid (ECF) DA levels were measured. PK and PD models were used to describe the relationship between the AHN 1-055, cocaine and DA levels. RESULTS: No significant (p< 0.05) differences were found in the PK parameters of AHN 1-055 alone (V(dss) = 18.7 l/kg, Cl = 1.8 l/h/kg and t(1/2) = 7.69 h) or AHN 1-055 with cocaine (V(dss)=17.4 l/kg, Cl = 1.9 l/h/kg and t(1/2) = 6.82 h). The brain-to-plasma (B/P) ratios (B/P(AHN 1-055) = 4.8 vs B/P(with cocaine) = 4.4) and half-lives (t(1/2(AHN 1-055)) = 6.2 h vs t(1/2(cocaine) = )5.6 h for AHN 1-055 alone and with cocaine were comparable. AHN 1-055 DA profiles were significantly different after co-administration with cocaine. There were no differences in the IC(50) for AHN 1-055, with cocaine, however, the IC(50) for cocaine was significantly reduced with AHN 1-055. CONCLUSIONS: The PK parameters of AHN 1-055 were not changed, however, the effect on DA levels was affected when cocaine was administered with AHNDA profile is affected when dosed with cocaine. This latter effect is a desirable attribute in the development of a medication as a potential substitute therapeutic medication for the treatment of cocaine abuse.

Fatal benztropine toxicity.

Benztropine is an anticholinergic agent used in the treatment of Parkinson's disease and drug induced extrapyramidal disorders. We report a case of fatal benztropine toxicity. This drug is regarded as relatively safe and reports of isolated toxicity are scarce. In ascribing a particular death to fatal drug toxicity the forensic pathologist must take into account the circumstances surrounding the death, the presence and significance of any co-existent natural disease and the potential contribution of any other detected therapeutic or illicit agents. This interpretation will occur in the knowledge that certain drugs will not be detected and that with respect to quantification of postmortem drug levels, the notion of postmortem redistribution should always be considered.

Development of a sensitive and specific radioimmunoassay for benztropine.

A benztropine RIA based on polyclonal antisera raised in New Zealand white rabbits has been developed. The drug-protein conjugates employed had a variety of moles of benztropine hemisuccinate coupled per mole of protein (bovine serum albumin or bovine thyroglobulin). Six antisera were developed and the one with the highest titer was further evaluated for its cross reactivity to N-desmethylbenztropine (4%) and the antipsychotic agents fluphenazine, flupenthixol, chlorpromazine, and haloperidol (all < 1%). The selected antiserum demonstrated sufficient sensitivity to measure benztropine from 0.156 to 100 ng/mL plasma in a 200-microL plasma sample, with a mean CV of < 6%. The RIA was applied to the analysis of steady-state plasma samples obtained from patients undergoing treatment with benztropine and plasma samples obtained from human volunteers and dogs orally dosed with the drug. Both the human and dog plasma samples, when analyzed after hydrolysis with beta-glucuronidase/sulfatase, demonstrated increments in benztropine concentrations, suggesting the drug may be undergoing biotransformation to phase II metabolite(s). In addition, when benztropine was selectively extracted from the unhydrolyzed plasma samples, there was a significant decrease in drug level, which further suggested that the antiserum cross reacted with phase II metabolite(s). The shape of the plasma concentration versus time profile obtained from the dog studies suggested that the drug might also undergo enterohepatic recycling.

The assay of tropane derivatives in formulations by second derivative ultraviolet spectrophotometry.

The development of a second order derivative spectrophotometric assay of atropine, hyoscine and benztropine in formulations is described. The assay involves the extraction into 1,2-dichloroethane of the tetraphenylborate salt of the alkaloids precipitated from pH 6 solution by an excess of sodium tetraphenylboron and measurement of the amplitude near 273 nm to its shorter wavelength satellite in the second derivative spectrum. The second derivative amplitude gives a more precise determination of the alkaloids than absorbance. A two-point bracketing standardization of the amplitude is required owing to a small but significant intercept in the calibration data. The procedures are sufficiently sensitive and precise for the batch and unit-dose assay of tablets of atropine sulphate (0.6 mg) hyoscine hydrobromide (0.3 mg) and benztropine mesylate (2 mg), and for the assay of atropine sulphate injection (0.4 mg ml-1) and tincture of belladonna.