Development and validation of a generic high-performance liquid chromatography for the simultaneous separation and determination of six cough ingredients: Robustness study on core-shell particles.

A generally applicable high-performance liquid chromatographic method for the qualitative and quantitative determination of pharmaceutical preparations containing phenylephrine hydrochloride, paracetamol, ephedrine hydrochloride, guaifenesin, doxylamine succinate, and dextromethorphan hydrobromide is developed. Optimization of chromatographic conditions was performed for the gradient elution using different buffer pH values, flow rates and two C18 stationary phases. The method was developed using a Kinetex® C18 column as a core-shell stationary phase with a gradient profile using buffer pH 5.0 and acetonitrile at 2.0 mL/min flow rate. Detection was carried out at 220 nm and linear calibrations were obtained for all components within the studied ranges. The method was fully validated in agreement with ICH guidelines. The proposed method is specific, accurate and precise (RSD% < 3%). Limits of detection are lower than 2.0 µg/mL. Qualitative and quantitative responses were evaluated using experimental design to assist the method robustness. The method was proved to be highly robust against 10% change in buffer pH and flow rate (RSD% < 10%), however, the flow rate may significantly influence the quantitative responses of phenylephrine, paracetamol, and doxylamine (RSD% > 10%). Satisfactory results were obtained for commercial combinations analyses. Statistical comparison between the proposed chromatographic and official methods revealed no significant difference.

Determinants of adherence to delayed-release doxylamine and pyridoxine in patients with nausea and vomiting of pregnancy.

OBJECTIVE: Women often hesitate to take medications in pregnancy due to fears of perceived potential fetal damage. The authors' objective is to identify the determinants of adherence to delayed-release doxylamine-pyridoxine (Diclectin) in patients with nausea and vomiting of pregnancy (NVP). METHODS: The authors performed a prespecified secondary analysis of a multicenter double-blind randomized controlled trial of Diclectin versus placebo for the treatment of NVP. Data on adherence to study medication were collected in all patients. The primary outcome of this analysis was adherence to study medication, which was determined by pill counting and patient diaries. The treatment regimen in the original trial was not fixed and depended on patient's symptoms. There was no difference in the adherence rates between subjects in the Diclectin or placebo arms of the study, so the 2 arms were analyzed as one cohort. The degree of adherence was analyzed in the various subgroups. Subsequently, a multiple linear regression model was constructed to identify predictors to adherence. RESULTS: Two hundred fifty-eight women were included in this analysis. There were no differences in adherence rates according to ethnicity, race, or the presence of adverse events. Gravidity, average number of prescribed tablets per day, site of enrollment, and change in NVP severity measured by the pregnancy unique-quantification of emesis score were associated with adherence. In multivariable analysis, average number of tablets per day, change in pregnancy unique-quantification of emesis, number of treatment days, site of enrollment were significantly predictive of adherence, with the former being negatively correlated. CONCLUSION: Adherence to antinauseants for NVP is affected by number of tablets prescribed per day, and treatment duration and effectiveness.

Harnessing of Doxylamine Succinate/Pyridoxine Hydrochloride-Dual Laden Bilosomes as a Novel Combinatorial Nanoparadigm for Intranasal Delivery: In Vitro Optimization and In Vivo Pharmacokinetic Appraisal.

The present work is concerned with tailoring and appraisal of a novel nano-cargo; bilosomes (BLS) dual laded with doxylamine succinate (DAS) and pyridoxine hydrochloride (PDH), the first treatment option against gestational nausea and vomiting, for intranasal delivery. This bifunctional horizon could surmount constraints of orally-commercialized platforms both in dosage regimen and pharmacokinetic profile. For accomplishing this purpose, DAS/PDH-BLS were elaborated integrating phospholipid, sodium cholate and cholesterol applying thin-film hydration method based on Box-Behnken design. Utilizing Design-Expert® software, the effect of formulation variables on BLS physicochemical features alongside the optimal formulation selection were investigated. Then, the optimum DAS/PDH-BLS formulation was incorporated into a thermally-triggered in situ gelling base. The in vivo pharmacokinetic studies were explored in rats for intranasal DAS/PDH-BLS in situ gel compared with analogous intranasal free in situ gel and oral solution. The optimized BLS disclosed vesicle size of 243.23 nm, ζ potential of -31.33 mV, entrapment efficiency of 59.18 and 41.63%, accumulative % release within 8 h of 63.30 and 85.52% and accumulative permeated amount over 24 h of 347.92 and 195.4 µg/cm2 for DAS/PDH, respectively. Following intranasal administration of the inspected BLS in situ gel, pharmacokinetic studies revealed a 1.64- and 2.3-fold increment in the relative bioavailability of DAS and a 1.7- and 3.73-fold increase for PDH compared to the intranasal free in situ gel and oral solution, respectively besides significantly extended mean residence times for both drugs. Thus, the intranasally exploited DAS/PDH-BLS could be deemed as a promising hybrid nanoplatform with fruitful pharmacokinetics and tolerability traits.

Simultaneous determination of a ternary mixture of doxylamine succinate, pyridoxine hydrochloride, and folic acid by the ratio spectra-zero-crossing, double divisor-ratio spectra derivative, and column high-performance liquid chromatographic methods.

Three simple, rapid, and accurate methods, i.e., the derivative ratio spectra-zero-crossing method (method I), double divisor-ratio spectra derivative method (method II), and column reversed-phase high-performance liquid chromatographic (RP-HPLC) method (method III) were developed for the simultaneous determination of doxylamine succinate (DOX), pyridoxine hydrochloride (PYR), and folic acid (FA) in their ternary mixtures and in tablets. In methods I and II, the calibration graphs were linear in the range of 2.5-80, 1.0-40, and 1.0-30 microg/mL for DOX, PYR, and FA, respectively. In the HPLC method, the separation of these compounds was performed using mobile phase consisting of 0.05 M phosphate buffer (pH 6.3)-methanol-acetonitrile (50 + 20 + 30, v/v/v), and UV detection was performed at 263 nm. Linearity was observed between the concentrations of the analytes and peak areas [correlation coefficient (r) > or =0.9998] in the concentration range of 1.0-200, 4.0-600, and 4.0-600 microg/mL for DOX, PYR, and FA, respectively. The standard deviation of retention time in method III was 0.011, 0.015, and 0.016 for DOX, PYR, and FA, respectively. The precision studies for all of the methods gave relative standard deviation values of <2%. The results obtained from the methods were statistically compared by means of Student's t-test and the variance ratio F-test. It was concluded that all of the developed methods were equally accurate, sensitive, and precise. These methods could be applied to determine DOX, PYR, and FA in their combined dosage forms.

Advanced spectrophotometric chemometric methods for resolving the binary mixture of doxylamine succinate and pyridoxine hydrochloride.

The prediction power of partial least squares (PLS) and multivariate curve resolution-alternating least squares (MCR-ALS) methods have been studied for simultaneous quantitative analysis of the binary drug combination - doxylamine succinate and pyridoxine hydrochloride. Analysis of first-order UV overlapped spectra was performed using different PLS models - classical PLS1 and PLS2 as well as partial robust M-regression (PRM). These linear models were compared to MCR-ALS with equality and correlation constraints (MCR-ALS-CC). All techniques operated within the full spectral region and extracted maximum information for the drugs analysed. The developed chemometric methods were validated on external sample sets and were applied to the analyses of pharmaceutical formulations. The obtained statistical parameters were satisfactory for calibration and validation sets. All developed methods can be successfully applied for simultaneous spectrophotometric determination of doxylamine and pyridoxine both in laboratory-prepared mixtures and commercial dosage forms.

Doxylamine succinate overdose: Slurred speech and visual hallucination.

Derinöz-Güleryüz O. Doxylamine succinate overdose: Slurred speech and visual hallucination. Turk J Pediatr 2018; 60: 439-442. Doxylamine succinate is a commonly used antihistamine for respiratory allergies including allergic rhinitis as well as for the management of insomnia. As it is available over-the-counter like other nonprescription antihistamines and sleep aids, there is a risk of overdose. It is believed that doxylamine succinate has both peripheral and central activity with its anticholinergic properties. Delirium, seizures, and coma are among the central adverse effects that are rare. This case was presented since it is the first case in the literature who developed slurred speech and visual hallucination after high dose doxylamine succinate use and received antidotal therapy for anticholinergic side effects.

Drug updates and approvals: 2018 in review.

In 2018, the FDA approved several new drugs for use in primary care. This article highlights the following new drugs: bictegravir, emtricitabine, and tenofovir alafenamide (Biktarvy); doxylamine succinate and pyridoxine hydrochloride (Bonjesta); erenumab-aooe (Aimovig); lofexidine hydrochloride (Lucemyra); tezacaftor and ivacaftor (Symdeko); and tildrakizumab-asmn (Ilumya).

A Phase I Study of the Pharmacokinetics and Pharmacodynamics of Intranasal Doxylamine in Subjects with Chronic Intermittent Sleep Impairment.

INTRODUCTION: Doxylamine tablets are approved as an over-the-counter sleep aid. We developed a doxylamine succinate intranasal metered-dose delivery system with the expectation of a more rapid onset of action with reduced side-effect potential compared with the oral tablet. METHODS: This phase I study randomized 24 adults with chronic intermittent sleep impairment to receive either single doses of intranasal doxylamine succinate 3.2, 6.3, or 12.7 mg or doxylamine succinate 25-mg oral tablet. Doxylamine pharmacokinetics were assessed using noncompartmental methods; pharmacodynamics were evaluated using the Karolinska Sleepiness Scale (KSS) and numerous psychomotor tests. Adverse events (AEs) were monitored. RESULTS: None of the intranasal dose levels produced a mean maximum plasma concentration (Cmax) above the 50 ng/mL target level or a time to maximum concentration shorter than that of the oral tablet. At the highest intranasal dose, Cmax and area under the doxylamine concentration-time curve were approximately 25% of the values achieved with the oral dose. Variation in most pharmacokinetic parameters was higher with intranasal compared with oral dosing. A relationship between plasma doxylamine concentration and KSS change from baseline was evident for the 25-mg tablet and, to a lesser extent, for the 12.7-mg intranasal dose. Changes from baseline in psychomotor parameters did not show a relationship to intranasal dose, and did not distinguish between intranasal versus oral dosing. The most common AEs with intranasal dosing were nasal congestion, nasal dryness, and frontal headache. CONCLUSION: The nasal spray did not increase doxylamine absorption or systemic bioavailability compared with the oral tablet.

Efficacy of a single evening dose of syrup containing paracetamol, dextromethorphan hydrobromide, doxylamine succinate and ephedrine sulfate in subjects with multiple common cold symptoms.

OBJECTIVE: The aim of this study was to evaluate the efficacy of a single night-time dose of a syrup containing paracetamol, dextromethorphan hydrobromide, doxylamine succinate and ephedrine sulfate in subjects with multiple cold symptoms. MATERIALS: A syrup containing 15 mg dextromethorphan hydrobromide, 7.5 mg doxylamine succinate, 600 mg paracetamol and 8 mg ephedrine sulfate (Wick MediNait produced by WICK Pharma, Germany, a subsidiary of Procter & Gamble GmbH; test syrup) or placebo (placebo syrup) for oral administration. METHODS: This was a randomized, double-blind, placebo-controlled, multi-center, parallel design study. At enrollment, eligible subjects had to have at least moderate nasal congestion and a runny nose, at least mild cough and at least mild pain with one or more of the following: sore throat, sore chest, headache or body pain/aches. Subjects were randomized into either Group T (test syrup) or Group P (placebo syrup). On the evening of enrollment, subjects rated baseline symptoms, ingested the assigned study product and completed symptom-relief assessments at 3 hours post-dosing. Within one hour of awakening the following morning, subjects completed night-time symptom relief and sleep satisfaction assessments. All symptoms were recorded using an Interactive Voice Response system. Treatment comparisons were made after adjusting for the severity of baseline symptom using analysis of covariance. RESULTS: Of 485 subjects who took the study product, 432 (224 in Group T; 208 in Group P) were evaluable for analysis. For the primary endpoint (composite of nasal congestion/runny nose/cough/pain relief scores 3 hours post-dosing), subjects in Group T had clinically and statistically significantly greater relief than Group P (p = 0.0002). Each individual symptom score also showed statistically significant improvement at this time point (p < or = 0.017). The next morning, Group T continued to show clinically and statistically significant benefits over Group P on the composite score and each of the individual symptoms (p < or = 0.003). Evidence of benefit with the test syrup was also seen in the higher score for overall night-time relief (p < 0.0001) and greater satisfaction on sleep (p = 0.002) compared to placebo syrup. Improvement in individual symptoms after 3 hours was obtained in 16-42% more subjects in Group T than in Group P, whereas the percentage of subjects in Group T having Good or Very Good relief the morning after dosing increased by 25-68% compared to subjects in Group P. 14 subjects (5 in Group T; 9 in Group P) reported AEs but none of these occurred with an incidence greater than 1%. There were no serious AEs. CONCLUSIONS: The results confirm the multisymptom benefit of a single dose of the test syrup containing paracetamol, dextromethorphan hydrobromide, doxylamine succinate and ephedrine sulfate and support its role as an effective and convenient therapy for symptoms of nasal congestion, runny nose, cough and pain/body aches associated with the common cold and for increasing sleep quality disturbed by the common cold.

Doxylamine and diphenhydramine pharmacokinetics in women on low-dose estrogen oral contraceptives.

Thirteen women chronically using low-dose estrogen-containing oral contraceptives (50 micrograms or less of ethinyl estradiol or its equivalent for a minimum of 3 months) and 12 age-matched drug-free control women received a single 25 mg oral dose of doxylamine succinate in the fasting state. Ten women taking oral contraceptives and ten controls received a single 50 mg oral dose of diphenhydramine hydrochloride. Multiple plasma samples drawn during 30 hours following the dose of doxylamine, and 12 hours after diphenhydramine dosage, were analyzed by gas chromatography using nitrogen-phosphorus detection. Mean pharmacokinetic variables for doxylamine in control and oral contraceptive groups were: peak plasma concentration, 103 vs 100 ng/ml; time of peak, 2.40 vs 1.87 hours after dosage, elimination half-life, 10.1 vs 10.2 hours; and total clearance, 3.70 vs 3.88 ml/min/kg. Mean pharmacokinetic variables for diphenhydramine in control and oral contraceptive groups were: peak plasma concentration, 63.7 vs 73.8 ng/ml; time of peak, 2.7 vs 2.2 hours after dosage; elimination half-life, 6.0 vs 5.1 hours; and total clearance, 21.8 vs 25.5 ml/min/kg. None of these differences were statistically significant. Thus, low-dose estrogen-containing oral contraceptives do not significantly influence the pharmacokinetics of the antihistamines doxylamine or diphenhydramine.

Dose-response trend tests for tumorigenesis, adjusted for body weight.

Several studies have demonstrated a relationship between rodent body weight and tumor incidence for some tissue/organ sites. It is not uncommon for a chemical tested for carcinogenicity to also affect body weight. In such cases, comparisons of tumor incidence may be biased by body-weight differences across dose groups. A simple procedure was investigated for reducing this bias. This procedure divides the animals into a few groups based on body weight. Body weight at 12 months was used, before the appearance of a tumor was likely to affect body weight. Statistics for dose-response trend tests are calculated within body weight strata and pooled to obtain an overall dose-response trend test. This procedure is analogous to that currently used, of stratifying animals, based on their age at the time of removal from a study. Age stratification is used to account for differences in animal age across dose groups, which can affect comparisons of tumor incidence. Several examples were investigated where the high-dose group had reduced body weights and associated reductions in tumor incidence. When the data were analyzed by body-weight strata, some positive dose-response trends for tumor incidence were demonstrated. In one case, the weight-adjusted analysis indicated that a negative dose-response trend in tumor incidence was a real effect, in addition to a body weight reduction. These examples indicate that it is important to consider the effects of body weight changes as low as 10%, and perhaps below, that were caused by chemicals in 2-year bioassays for carcinogenesis. The simple procedure of analyzing tumor incidence within body-weight strata can reduce the bias introduced by weight differences across dose groups.

Double-blind trial of a long-acting bronchodilator preparation ("Nethaprin Dospan") in bronchospastic disease.

A double-blind, placebo-controlled, crossover study was carried out in 48 patients with bronchospastic disease to assess the efficacy of a long-acting bronchodilator preparation ("Nethaprin Dospan") containing etafedrine hydrochloride, bufylline, doxylamine succinate and phenylephrine. Patients received 1 tablet nightly, with an extra dose in the morning if necessary, of active drug or placebo for 1 week, and were then crossed over to the alternative medication for a further week. All patients had marked disability, apparent on initial clinical examination and on respiratory function tests. The results showed that FEV1 and VC were significantly improved with the active medication, and patients slept better, had improved appetite and suppression of cough.

Mutagenicity testing of doxylamine succinate, an antinauseant drug.

Doxylamine succinate (DA), a compound which was formerly used as an antinauseant during pregnancy, showed no substantial mutagenicity in mouse embryos following transplacental exposure. A small dose-dependent induction of chromosomal aberrations was found in mouse embryos on day 11 of gestation. No induction of sister chromatid exchanges (SCE) was found in embryos on day 11 of gestation. A micronucleus test with fetal blood on day 17 of gestation was negative. Additionally, DA was negative in Chinese hamster bone marrow in vivo (micronuclei) and in human lymphocyte cultures in vitro (SCE).

Doxylamine overdose as a potential cause of rhabdomyolysis.

Doxylamine succinate, an over-the-counter antihistamine, is commonly used as a nighttime sleep aid in the short-term management of insomnia. It is also used in combination with antitussive and decongestant agents for the temporary relief of common cold symptoms. Doxylamine is frequently involved in accidental and intentional overdoses. Rhabdomyolysis and secondary acute renal failure are rare but potentially serious complications, making early recognition and treatment essential. With the large number of nonprescription antihistamines and sleep aids available to the general public, it is important to keep in mind that overdose is a potential problem. The complications associated with overdose of these medications are just as life threatening as those associated with prescription drugs. A high index of suspicion and evaluation of rhabdomyolysis is warranted in antihistamine toxicity. We report an observation of severe rhabdomyolysis associated with doxylamine overdose.

A clinical study to evaluate the efficacy of the antihistamine doxylamine succinate in the relief of runny nose and sneezing associated with upper respiratory tract infection.

Antihistamines are widely used in common cold medications, although the role of histamine in the development of common cold symptoms is unclear and the use of antihistamines for the treatment of common cold is controversial. It is clear that antihistamines do not offer a cure for common cold but they may alleviate symptoms of sneezing and runny nose. The present study was designed to investigate the efficacy of an antihistamine, doxylamine, on the symptoms of runny nose and sneezing associated with common cold. We conducted a randomized double-blind study in cold sufferers. One thousand and one volunteers with cold symptoms were screened in four centres (UK, Denmark, Belgium, Germany) and 688 satisfied the entry criteria of the study. The main reasons for excluding subjects were a low nasal secretion weight (secretion weight < 0.2g, 72%) and a low subjective rhinorrhoea score (24%). Volunteers were randomized to receive either doxylamine succinate 7.5 mg by mouth four times a day up to nine doses (n = 345) or placebo (n = 343). The principal measurements were prospectively defined as runny nose and sneezing symptom scores. Data were analysed on an intention-to-treat basis, using Cochran-Mantel-Haenszel statistics controlling for baseline symptom scores. A between-group comparison showed that doxylamine-treated volunteers benefited from a significantly greater reduction in runny nose scores (P < 0.01) and sneezing scores (P < 0.001), than those volunteers in the placebo group. Doxylamine therapy was well tolerated; the incidence of unexpected side-effects was comparable with placebo. Of the expected side-effects, 13.3% of doxylamine-treated patients reported drowsiness. The incidence of sedative effects was lower than has been reported for other commonly used first-generation antihistamines.

Metabolism of doxylamine succinate in Fischer 344 rats. Part I: Distribution and excretion.

Experiments were conducted with male and female rats (12 per group) dosed by gavage with 2 or 20 mg (based on the free amine) doxylamine succinate containing about 10 microCi 14C-doxylamine succinate to determine distribution and excretion of the activity as a function of dose and sex with time. Urine and feces were collected at intervals up to 72 hr. Most of the dose (approximately equal to 70%) was eliminated in the first 24 hr after dosing and 95 to 100% of the dose was recovered during the 72-hr course of the experiments with both sexes and dose levels. Less than 1% of the total dose remained in the rats at the end of the test period. The urinary route of elimination was more predominant than the fecal route in both sexes given the 20-mg dose. The fecal route predominates in low-dose males whereas there is no significant difference between urinary and fecal routes of elimination in low-dose females. Preliminary characterization of urinary metabolite form using extraction techniques shows 99% of the metabolites to be in the polar conjugated form.

Metabolism of 14C-labeled doxylamine succinate (Bendectin) in the rhesus monkey (Macaca mulatta).

The time-course of the metabolic fate of [14C]doxylamine was determined after the p.o. administration of 13 mg/kg doxylamine succinate as Bendectin plus [14C]doxylamine succinate to the rhesus monkey. Urine and plasma samples were analyzed by reversed-phase high performance liquid chromatography (HPLC), chemical derivatization, and mass spectrometry. The cumulative 48-hr urinary metabolic profile contained 81% of the administered radiolabeled dose and consisted of at least six radiolabeled peaks. They were peak 1: unknown polar metabolites (8% of dose); peak 2: 2-[1-phenyl-1-(2-pyridinyl)ethoxy] acetic acid, 1-[1-phenyl-1(2-pyridinyl)ethoxy] methanol, and another minor metabolite(s) (31%); peak 3: doxylamine-N-oxide (1%); peak 4a: N,N-didesmethyldoxylamine (17%); peak 4b: doxylamine (4%); and peak 5: N-desmethyldoxylamine (20%). The plasma metabolic profile was the same as the urinary profile except for the absence of doxylamine-N-oxide. The maximum plasma concentrations and elapsed time to attain these concentrations were as follows. Peak 1: 540 ng/mL, 4 hr; peak 2: 1700 ng/mL, 1 hr; peak 4a: 430 ng/mL, 4 hr; peak 4b: 930 ng/mL, 2 hr; and peak 5: 790 ng/mL, 2 hr. These data suggest that in the monkey, doxylamine metabolism follows at least four pathways: a minor pathway to the N-oxide; a minor pathway to unknown polar metabolites; a major pathway to mono- and didesmethyldoxylamine via successive N-demethylation; and a major pathway to side-chain cleavage products (peak 2) via direct side-chain oxidation and/or deamination.

Metabolism of doxylamine succinate in Fischer 344 rats. Part III: Conjugated urinary and fecal metabolites.

Elimination and metabolic profiles of the glucuronide products of doxylamine and its N-demethylated metabolites were determined after the oral administration of (14C)-doxylamine succinate (13.3 and 133 mg/kg doses) to male and female Fischer 344 rats. The cumulative urinary and fecal eliminations of these conjugated doxylamine metabolites at the 13.3 mg/kg dose were 44.4 +/- 4.2% and 47.3 +/- 8.1% of the total recovered dose for male and female rats, respectively. The cumulative urinary and fecal eliminations of conjugated doxylamine metabolites at the 133 mg/kg dose were 55.2 +/- 2.6% and 47.9 +/- 2.5% of the total recovered dose for male and female rats, respectively. The conjugated doxylamine metabolites that were isolated, quantitated, and identified are doxylamine O-glucuronide, N-desmethyl-doxylamine O-glucuronide, and N,N-didesmethyldoxylamine O-glucuronide.

Metabolism of doxylamine succinate in Fischer 344 rats. Part II: Nonconjugated urinary and fecal metabolites.

Elimination and metabolic profiles of doxylamine and its nonconjugated metabolites were determined after the oral administration of [14C]-doxylamine succinate (13.3 mg/kg and 133 mg/kg doses) to male and female Fischer 344 rats. Total urine and fecal recovery of the administered dose was greater than 90% regardless of sex or dose. The cumulative urinary and fecal elimination of these nonconjugated doxylamine metabolites at the 13.3 mg dose was 44.4 +/- 4.4% and 36.0 +/- 5.8% of the total recovered dose for male and female rats, respectively. The cumulative urinary and fecal elimination of the doxylamine nonconjugated metabolites at the 133 mg/kg dose was 38.7 +/- 2.7% and 41.4 +/- 1.0% of the total recovered dose for male and female rats, respectively. In order to determine the contribution of mammalian and bacterial enzymes in the overall metabolism and excretion patterns for doxylamine, two in vitro techniques were investigated. Incubation of [14C]-doxylamine succinate with human and rat intestinal microflora indicated that anaerobic bacteria were not capable of effecting the degradation of [14C]-doxylamine succinate. However, the incubation of [14C]-doxylamine succinate with isolated rat hepatocytes generated several metabolites similar to those observed in vivo. The nonconjugated doxylamine metabolites isolated and identified include: doxylamine N-oxide, desmethyldoxylamine, didesmethyldoxylamine and ring-hydroxylated products of doxylamine and desmethyldoxylamine. The studies demonstrate the role of hepatic metabolism in the elimination of doxylamine succinate in the rat.

Trace analysis of doxylamine succinate in animal feed, human, urine, and wastewater by GC using a rubidium-sensitized nitrogen detector.

Doxylamine succinate, a drug used as a sleep-inducing agent, an antihistamine, and in a therapeutic formulation taken by pregnant women as an antinauseant, was scheduled for toxicological evaluation as part of a structure activity relationship study, with rats and mice, because a deficiency of such data exists with regard to many antihistamines. Analytical chemical procedures that ensure proper concentration, homogeneity, and stability of the drug in dosed feed, as well as the safety of personnel and the environment, were prerequisites for the toxicological tests. GC methods using a rubidium-sensitized nitrogen detector were developed for analysis of doxylamine succinate in animal feed, human urine, and wastewater at levels as low as 1 ppm, 100 ppb, and 100 ppb, respectively. Sample extracts were cleaned up by liquid-liquid partitioning, followed by additional cleanup on a column of silica gel. Data are presented concerning the stability of the drug in animal feed, extraction efficiencies, and the use of the silica gel cleanup column to separate the caffeine interference from doxylamine in extracts of human urine. Partition values and ancillary data concerning analysis of the drug in feed, by HPLC at levels as low as 10 ppm, are also reported.