Stability of ondansetron hydrochloride and 12 medications in plastic syringes

The stability and compatibility of ondansetron hydrochloride with neostigmine methylsulfate, naloxone hydrochloride, midazolam hydrochloride, fentanyl citrate, alfentanil hydrochloride, atropine sulfate, morphine sulfate, meperidine hydrochloride, propofol, droperidol, metoclopramide monohydrochloride, and glycopyrrolate were studied. Ondansetron 1.33 or 1.0 mg/mL was combined with 0.9% sodium chloride injection and each of the 12 drugs in duplicate in plastic syringes (or glass for propofol). The syringes were stored at 21.8-23.4 or 4 degrees C in the dark, except for those containing propofol, which were stored at ambient temperature. Samples were removed at 0, 4, 8, and 24 hours for analysis by high-performance liquid chromatography and pH measurement; the propofol-containing samples were removed at 0, 1, 2, and 4 hours. Syringes were visually assessed for color and clarity, and particulate content was measured with a particle counter at the end of the study period. All solutions containing ondansetron retained more than 90% of their initial ondansetron concentration. Solutions containing each of the other drugs except droperidol retained more than 90% of their initial concentration of these drugs. The solutions containing droperidol retained more than 90% of their initial droperidol concentration for up to eight hours at ambient temperature but precipitated quickly at 4 degrees C. In combinations of ondansetron 1.33 or 1.0 mg/mL and 10 of 12 drugs, all drugs were stable for 24 hours in plastic syringes at 23 and 4 degrees C; ondansetron hydrochloride 1.0 mg/mL and propofol 1.0 and 5.0 mg/mL in admixtures were stable for 4 hours, and droperidol on its own and combined with ondansetron 1.0 mg/mL was stable for no more than 8 hours at ambient temperature.

Enantioselective determination of S-(+)- and R-(-)-ondansetron in human serum using derivatized cyclodextrin-modified capillary electrophoresis and solid-phase extraction

A high-performance capillary electrophoresis (HPCE) assay method for the quantitation of S-(+)- and R-(-)-ondansetron in human serum was developed. Resolution was achieved using 15 mM heptakis-(2, 6-di-O-methyl)-beta-cyclodextrin (DM-beta-CD) in 100 mM phosphate buffer (pH 2.5). A 72-cm untreated fused-silica capillary, at a constant voltage of 20 kV, was used for the analysis. A 0.03-mM cationic detergent was used as a buffer additive to decrease the adsorption of endogenous substances onto the silica wall. The analytes of interest were isolated from endogenous substances using a solid-phase extraction procedure. The cyanopropyl cartridge gave good recoveries in excess of 85% for both S-(+)- and R-(-)-ondansetron, without any interferences. To decrease the limits of detection of the analytes, an on-capillary sample concentration technique was employed. The detection limit was 10 ng/ml using 2 ml of serum and the limit of quantitation was 15 ng/ml. The calibration curve was linear over a range of 15-250 ng/ml, with procainamide as the internal standard, and the coefficients of determination obtained were greater than 0.999 (n = 3). Precision and accuracy of the method were 2.76-5.80 and 2.10-5.00%, respectively, for S-(+)-ondansetron, and 3.10-6.57 and 2.50-4.35%, respectively, for R-(-)-ondansetron. The HPCE method is a useful alternative to existing chiral high-performance liquid chromatographic methods.

Ondansetron hydrochloride: a competitive serotonin 5-HT3 receptor blocker

The methyl substituted imidazole ring in the title compound, 2-methyl-1-(9-methyl-4-oxo-2,3,4,9-tetrahydro-1H-carbazol-3-yl) imidazol-3-ium chloride dihydrate, C18H20N3O+.Cl-.2H2O, is approximately perpendicular to the carbazole plane [dihedral angle 87.0(1) degrees]. The water molecules are involved in an elaborate network of hydrogen bonds that reinforce the stability of the dihydrate and the cohesion of the structure.

Compatibility of ondansetron hydrochloride with meperidine hydrochloride for combined administration

OBJECTIVE

To determine the physical compatibility and chemical stability of ondansetron hydrochloride 0.1 and 1 mg/mL with meperidine hydrochloride 4 mg/mL admixed in NaCl 0.9% injection USP.

DESIGN

Triplicate test solutions of the drugs in NaCl 0.9% injection USP were prepared and stored at 4, 22, and 32 degrees C. Samples were removed initially and at various time points over 31 days and were stored at -70 degrees C until they were analyzed. Physical compatibility was assessed by measuring solution turbidity with a color-correcting turbidimeter and particle content with a light-obscuration particle sizer/counter, as well as by visual assessment. Chemical stability of the drugs was determined using a stability-indicating HPLC analytic method. Duplicate determinations were performed on each sample to measure the concentration of each drug.

RESULTS

All admixtures were found to exhibit no visual or subvisual changes of consequence in turbidity or particle content at all observation points. Further, little or no loss of any of the drugs occurred in any concentration throughout the study.

CONCLUSIONS

The physical compatibility and chemical stability of ondansetron hydrochloride with meperidine hydrochloride under the conditions of this study have been established for 7 days at 32 degrees C and 31 days at 4 and 22 degrees C.

Stability of ondansetron hydrochloride injection in various beverages

The stability of ondansetron hydrochloride injection in beverages likely to be acceptable to patients was studied. Ondansetron hydrochloride injection (containing ondansetron 2 mg/mL) was added to apple juice, fruit punch, cherry-flavored drink, carbonated soft drinks, and hot tea to provide a nominal ondansetron concentration of 32.8, 64.5, or 95.2 micrograms/mL. Samples were stored at -3 to 28 degrees C (noncarbonated-beverage mixtures except tea), 2 to 28 degrees C (carbonated-beverage mixtures), and 25 degrees C (tea) and assayed for ondansetron concentration by high-performance liquid chromatography at 6, 24, 48, and 72 hours (noncarbonated-beverage mixtures except tea); 6, 24, and 48 hours (carbonated-beverage mixtures); and 1 hour (tea). More than 95% of the initial ondansetron concentration was retained in apple juice, fruit punch, cherry-flavored drink, Sprite, and Diet Coke throughout the periods studied. A precipitate formed immediately after ondansetron was added to hot tea, but the drug was chemically stable for at least one hour in this preparation. Ondansetron hydrochloride injection 32.7, 64.5, and 95.2 micrograms/mL (expressed as free base) was stable in various beverages when stored at -3 to 28 degrees C for up to 72 hours. Ondansetron at these same concentrations precipitated in hot tea preparations but was chemically stable for at least one hour.

Ondansetron clinical pharmacokinetics

Ondansetron is a potent and highly selective serotonin 5-HT3-receptor antagonist which has demonstrated important antiemetic activity and good tolerability in the prevention of chemotherapy-induced nausea and vomiting. Ondansetron is completely and rapidly absorbed from the gastrointestinal tract after oral administration, and does not accumulate with repeated oral administration. Owing to hepatic first-pass metabolism, its bioavailability is only about 60% compared with ondansetron administered by infusion over 15 minutes. Bioavailability is slightly increased when administered after a standard meal, and is not influenced by coadministration of antacids; a slightly enhanced bioavailability has been observed in patients with cancer. Since the time to reach peak concentration is 0.5 to 2 hours after oral ingestion, the drug should be administered at least 30 minutes before chemotherapy. Possible alternative ways of administration of ondansetron include intramuscular, subcutaneous and rectal administration, and oral controlled-release formulations. Ondansetron is widely distributed (volume of distribution approximately 160L) and binds moderately (70 to 76%) to plasma proteins; the elimination half-life averages approximately 3.8 +/- 1 hours. Clearance occurs by hepatic metabolism (95%) rather than renal excretion. Metabolites do not play a role in the activity of the drug, and there is no evidence of genetic polymorphic metabolism. Although aging is associated with decreased clearance and increased bioavailability, dosage adjustments are not required for the elderly, and may be necessary only in patients with severe hepatic impairment. Chemotherapeutic agents do not seem to modify the pharmacokinetics of ondansetron. There remains the question of whether control of emesis is related to systemic availability of ondansetron and, in consequence, the optimal dose and schedule of ondansetron is still to be identified with certainty.

Molecular surface comparison. 2. Similarity of electrostatic vector fields in drug design

In the first article of this series a real-time graphics method was described for molecular similarity of scalar properties. This has now been extended for the comparison of molecular vector properties, most notably electrostatic field. A comparison of the various techniques of calculating fields is presented that includes a new method based on natural orbital fitted point charges. In the two examples described, namely, a series of benzodiazepine agonists and a set of serotonin 5-HT3 antagonists, the program has been shown to produce useful pharmacophoric overlaps that can be used in the design of novel therapeutic agents.

Compatibility and stability of ondansetron hydrochloride with morphine sulfate and with hydromorphone hydrochloride in 0.9% sodium chloride injection at 4, 22, and 32 degrees C

The physical compatibility and chemical stability of ondansetron hydrochloride 0.1 and 1 mg/mL with morphine sulfate 1 mg/mL and with hydromorphone hydrochloride 0.5 mg/mL in 0.9% sodium chloride injection were studied. Test solutions of the drugs in 0.9% sodium chloride injection were prepared in triplicate and stored at 4, 22, and 32 degrees C. Samples were removed immediately and at various time points over 31 days and stored at -70 degrees C until analyzed. Physical compatibility was assessed visually and by measuring turbidity with a color-correcting turbidimeter and particle content with a light-obscuration particle sizer and counter. Chemical stability was determined by measuring the concentration of each drug in duplicate with stability-indicating high-performance liquid chromatography. There were no visual or subvisual changes in turbidity or particle content in any of the test solutions at any of the time points. There was little or no loss of any of the drugs. When admixed in 0.9% sodium chloride injection, ondansetron hydrochloride 0.1 and 1 mg/mL plus morphine sulfate 1 mg/mL or hydromorphone hydrochloride 0.5 mg/mL were compatible and stable for at least 7 days at 32 degrees C and for at least 31 days at 4 and 22 degrees C.

Stability of ondansetron stored in polypropylene syringes

OBJECTIVE

To evaluate the stability of ondansetron hydrochloride undiluted and mixed in dextrose 5% injection or NaCl 0.9% injection during storage in polypropylene syringes when frozen, refrigerated, or at room temperature.

DESIGN

Batch quantities of ondansetron 0.25, 0.5, 1.0, and 2.0 mg/mL were prepared and individual doses of 10.5 mg were drawn into polypropylene syringes that were stored at -20 degrees C for up to 3 months, at 4 degrees C for up to two weeks, or at 22-25 degrees C for two days, and various combinations of these conditions. At defined sampling times aliquots were withdrawn from syringes, the solution visually inspected, pH measured, and ondansetron concentration determined by HPLC. Drug loss of > or = 10 percent of the original content of the solution was considered clinically significant.

RESULTS

The ondansetron concentration in each solution, regardless of storage conditions, remained above 90 percent of the original concentration at each observation time (range 92-107 percent). No changes in color or clarity of any of the solutions were observed, and only slight fluctuations in pH (< or = 0.05) were noted.

CONCLUSIONS

Ondansetron 2 mg/mL undiluted, or at concentrations of 0.25, 0.5, or 1 mg/mL, mixed in dextrose 5% injection or NaCl 0.9% injection was determined to be stable when stored in polypropylene syringes for each storage condition at all time points studied, including the maximum for each: three months at -20 degrees C, followed by 14 days at 4 degrees C, and by 48 hours at 22-25 degrees C.

Stability of paclitaxel with ondansetron hydrochloride or ranitidine hydrochloride during simulated Y-site administration

The stability of paclitaxel with either ondansetron hydrochloride or ranitidine hydrochloride during simulated Y-site injection at room temperature was studied. Triplicate test solutions of paclitaxel 0.3 and 1.2 mg/mL were admixed 1:1 with ondansetron 0.03 and 0.3 mg/mL (as the hydrochloride salt) or ranitidine 0.5 and 2.0 mg/mL (as the hydrochloride salt). Also, paclitaxel 1.2 mg/mL was admixed 1:1:1 with ondansetron 0.3 mg/mL and ranitidine 2.0 mg/mL. The solutions were stored in glass containers at room temperature, and samples were removed at zero, one, two, and four hours for immediate assay. At the time of the assay and before any dilution, each sample was visually inspected for clarity, color, and precipitation, and the pH was determined. Drug concentrations were measured by stability-indicating high-performance liquid chromatographic procedures. Throughout the study, more than 90% of the initial concentrations of paclitaxel, ondansetron, and ranitidine remained in the solutions. No precipitates, color changes, or haziness was seen. The changes in pH were minor. Paclitaxel in concentrations of 0.3 and 1.2 mg/mL was stable when mixed with either ondansetron (0.03 or 0.3 mg/mL, as the hydrochloride salt) or ranitidine (0.5 or 2.0 mg/mL, as the hydrochloride salt) and stored in glass containers for four hours. Paclitaxel 1.2 mg/mL was also stable when mixed with both ondansetron 0.3 mg/mL and ranitidine 2.0 mg/mL and stored in glass containers for four hours.

Development of high-affinity 5-HT3 receptor antagonists. Structure-affinity relationships of novel 1,7-annelated indole derivatives

On the basis of the structures of ondansetron and GR 65,630, its ring-opened C-linked methylimidazole analogue, novel 1,7-annelated indole derivatives were synthesized as potential 5-HT3 antagonists. Receptor binding studies show that all compounds display a high affinity for the 5-HT3 receptors. In both series annelation results in compounds being 7 and 4 times more potent than the references ondansetron and GR 65,630, respectively. Similar to ondansetron, the 1,7-annelated indoles show little stereoselectivity. The (-)-isomers are only slightly more potent than the (+)-isomers. The receptor binding profile of l-10-[(2-methyl-1H-imidazol-1-yl)methyl]-5,6,8,9,10,11-hexahydro-4H-pyri do [3,2,1-jk]carbazol-11-one hydrochloride (24b) (INN cilansetron) shows that the compound displays, besides a high affinity for 5-HT3 receptors (Ki = 0.19 nM), a weak affinity for sigma-receptors (Ki = 340 nM), muscarine M1 receptors (Ki = 910 nM), and 5-HT4 receptors (Ki = 960 nM) and no affinity (Ki > or = 5000 nM) for all the other receptor types tested (n = 37). The new compounds fit the proposed necessary chemical template for binding: a heteroaromatic ring system, a coplanar carbonyl group, and a nitrogen center at well-defined distances. The enhanced potency of the annelated 1,7-indole derivatives indicates that the extra ring provides a favorable hydrophobic area for interaction with the 5-HT3 receptor site. In vivo cilansetron is more potent and induces less central side effects than ondansetron. At present cilansetron is in clinical trials.