[Fortified antibiotic (vancomycin, amikacin and ceftazidime) eye drop stability assessment at -20 degrees C]. / Stabilité à -20 degrés C des collyres antibiotiques renforcés (amikacine, ceftazidime, vancomycine).

INTRODUCTION: Fortified antibiotic ophthalmic solutions are regularly administered as an immediate treatment for bacterial keratitis. Fortified antibiotics used to be self-prepared by nurses. To solve this problem, pharmacy staff studied the stability of three 5% solutions of vancomycin, amikacin, and ceftazidime prepared in aseptic conditions from parenteral antibiotic solutions. MATERIAL AND METHODS: Solutions were frozen at -20 degrees C. Each solution were examined before storage and over a 75-day period. Ceftazidime and amikacin were diluted in 0.9% sodium chloride and vancomycin in 5% dextrose. Over a 75-day period, physical and pharmacological (absorbance spectra) properties and the sterility of each stock solution were studied. RESULTS: The pH of amikacin (6.51), ceftazidime (6.47), and vancomycin (3.77) remained stable during the 75-day period. Osmolarities also remained stable (367, 488, and 351 mOsm/L, respectively). There were no significant differences in the concentration, osmolarity, and pH of the three antibiotic solutions before storage and after 75 days of freezing. Over a 75-day period, the stability of amikacin, ceftazidime, and vancomycin remained constant; no contamination was detected before storage and after 75 days. CONCLUSION: Topical fortified antibiotic solutions can be stored for 75 days at -20 degrees C (15 days quarantine). After this time, these eye-drops should be stored at 4 degrees C and should be discarded after 3 days.

Pharmacokinetics of all-trans retinoic acid, 13-cis retinoic acid, and fenretinide in plasma and brain of Rat.

We have measured the pharmacokinetics of three retinoids, all-trans retinoic acid, 13-cis retinoic acid, and fenretinide in rat blood and rat brain [especially white matter (WM) and gray matter (GM)] to help select retinoids for treating human malignant glioma. All-trans retinoic acid permeated well into the WM, giving peak concentration in WM of 25.7 microg/g, 6 to 7 times higher than the peak serum concentration. There was less 13-cis retinoic acid in WM: area under the curve (AUC)(0-->infinity) WM/AUC(0-->infinity) serum = 18.00 microg ml(-1) h/32.67 microg ml(-1) h. The ratio WM/GM was over 1 for these two compounds, but the half-lives were short in the serum and cerebral tissue (0.57-1.02 h). Fenretinide had different pharmacokinetics: the peak concentrations were in serum (1.7 microg/ml) and WM (1.2 microg/ml)-low, but the AUC(0-->infinity) was large (25.55 microg ml(-1) in serum and 57.53 microg ml(-1) in WM) due to its long elimination half-life (13.78 h in serum and 17.77 h in WM). These findings provide information that may be used to select a retinoid and establish therapeutic regimens that provide optimal efficacy with minimal toxicity.

Comparison of three advanced chromatographic techniques for cannabis identification.

The development of chromatography technology, with the increasing availability of easier-to-use mass spectrometers combined with gas chromatography (GC), the use of diode-array or programmable variable-wavelength ultraviolet absorption detectors in conjunction with high-performance liquid chromatography (HPLC), and the availability of scanners capable of reading thin-layer chromatography (TLC) plates in the ultraviolet and visible regions, has made for easier, quicker and more positive identification of cannabis samples that standard analytical laboratories are occasionally required to undertake in the effort to combat drug addiction. At laboratories that do not possess the technique of GC combined with mass spectrometry, which provides an irrefutable identification, the following procedure involving HPLC or TLC techniques may be used: identification of the chromatographic peaks corresponding to each of the three main cannabis constituents-cannabidiol (CBD), delta-9-tetrahydrocannabinol (delta-9-THC) and cannabinol (CBN)-by comparison with published data in conjunction with a specific absorption spectrum for each of those constituents obtained between 200 and 300 nm. The collection of the fractions corresponding to the three major cannabinoids at the HPLC system outlet and the cross-checking of their identity in the GC process with flame ionization detection can further corroborate the identification and minimize possible errors due to interference.

Plasma pharmacokinetics and metabolism of the benzodiazepine antagonist [11C] Ro 15-1788 (flumazenil) in baboon and human during positron emission tomography studies.

Flumazenil is a specific antagonist of the central benzodiazepine receptor (CBZR). Labelled with 11C, this compound is the reference radioligand for positron emission tomography (PET) study of the CBZR in humans and primates. The time-course of [11C]-flumazenil radioactivity and its main acid metabolite [11C] Ro 15-3890 were reconstructed from the time-course of total radioactivity in plasma after administration with high or low SRA in primates and humans, applying an extraction procedure validated by TLC. The measured pharmacokinetics of [11C]-flumazenil (T1/2 beta = 45.1 +/- 12.3 min, T1/2 alpha = 1.5 +/- 1.5 min; K = 0.14 +/- 0.14 min-1; Vd area = 44.0 +/- 17.0 l; Clp = 40.0 +/- 8.5 l/h) exhibited a very rapid distribution phase followed by fast elimination, with a large volume of distribution; these results were confirmed by HPLC determinations and agree with previously published data on unlabelled flumazenil. Pharmacokinetics of [11C] Ro 15-3890 acid metabolite show that high drug concentrations in the blood are promptly achieved (kf = 0.13 +/- 0.004 min-1), with a very rapid elimination half-life (T1/2m = 4.47 +/- 1.31 min) comparable to that of [11C]-flumazenil. The percentage metabolization of parent compound to the acid [11C] Ro 15-3890 was constant from the 15th minute and was significantly higher in man compared to the monkey. This percentage was increased by prior eating. The other putative metabolites, i.e. labelled [11C] Ro 15-4965 and unlabelled Ro 15-5528, were never observed at detectable concentrations with TLC and HPLC in rabbit, baboon and human blood samples. This pharmacokinetic study of plasma flumazenil may be useful to implement a dynamic method of CBZR quantification using PET and for analysis of pharmacokinetics in brain tissue.

[Comparison of the efficacy of verapamil and diltiazem in stable exercise angina. A double-blind and crossover study]. / Comparaison de l'efficacité du vérapamil et du diltiazem dans l'angor d'effort stable. Etude en double aveugle et en crossover.

Calcium channel blockers are now recommended for the treatment of stable angina but few studies have been carried out comparing the efficacy of verapamil and diltiazem in this indication. The short-term efficacy of these two drugs was compared in a double-blind crossover trial in 12 patients. The following protocol was used, 24 hour selection period followed by two crossover treatment periods versus double placebo. Exercise stress tests were performed 2 hours after the last dose at the end of each treatment period. Each patient underwent 3 stress tests: the first during the selection period whilst taking verapamil and diltiazem placebo (ET0), the second after the first treatment period at day 7 (ET1) and the third after the second treatment period at day 14 (ET2). A comparison of exercise capacity (ET0 to ET1 and ET2) showed improved effort tolerance and an increase in the ischaemic threshold with calcium blocker therapy. The duration of effort, the maximum sustained load, the rate-pressure product and the time to ST depression were all significantly increased. On the other hand, there were no significant changes in the percentage theoretical maximum heart rate attained, the heart rate at which ST depression occurred, the maximum ST depression and the incidence of angina. A comparison between ET1 and ET2 did not show any difference in the parameters of maximum effort or of the appearance of myocardial ischaemia. The comparison of exercise stress tests performed after treatment with verapamil and after diltiazem showed that the total duration of exercise, the maximum sustained load (in watts) and the rate-pressure product were identical.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacokinetics of intravenous ketoprofen. Therapeutic value in renal colic]. / Pharmacocinétique du kétoprofène intraveineux. Intérêt thérapeutique dans la colique néphrétique.

The pharmacokinetics of intravenous ketoprofen were evaluated in 37 patients suffering from acute ureteral colic. Four studies were established to obtain a rapid and persistent analgesic effect: group I: 100 mg of ketoprofen as bolus; group II: short infusion of 100 mg of ketoprofen (1.5 or 2 hours); group III: loading dose of 35 mg ketoprofen plus an infusion of 25 mg/h and 33 mg/h. Serum concentrations of ketoprofen were measured by high pressure liquid chromatography. The mean (+/- SD) values of pharmacokinetic parameters measured with a 2 open compartment model were as follows: distribution half-life: 0.34 +/- 0.19 h; elimination half-life: 2.05 +/- 0.58 h; kel: 0.96 +/- 0.28 h-1; k21: 0.94 +/- 0.42 h-1; k12: 1.00 +/- 0.70 h-1; volume of central compartment: 5.58 +/- 1.67 l; volume of tissue compartment: 5.14 +/- 2.12 l; plasma clearance: 5.10 +/- 1.14 l. h-1. These results concur with previously published data obtained after oral, rectal or intramuscular administration. Ketoprofen due to its peripheric anti-inflammatory, antiprostaglandins and central actions gives the best results with the intravenous administration. Administration of a ketoprofen bolus suppressed pain within ten minutes in 71% of patients.

Clinical pharmacokinetics of ketoprofen after single intravenous administration as a bolus or infusion.

The pharmacokinetics of ketoprofen were evaluated in 29 patients suffering from acute renal colic following a single intravenous administration as a bolus or short infusion (1.5 and 2 hours), and after a loading dose and a 24-hour infusion. Serum concentrations of ketoprofen were measured by high pressure liquid chromatography. The mean (+/- SD) values of clinical parameters were as follows: distribution half-life = 0.34 +/- 0.19 h; elimination half-life = 2.05 +/- 0.58 h; kel = 0.968 +/- 0.282 h-1; k21 = 0.943 +/- 0.425 h-1; k12 = 1.004 +/- 0.708 h-1; volume of central compartment = 5.58 +/- 1.67L; volume of tissue compartment = 5.14 +/- 2.12L; plasma clearance = 5.10 +/- 1.14L/h. These results concur with previously published data obtained after oral or intramuscular administration. According to clinical observations, administration of a ketoprofen bolus suppressed pain within 5 to 30 minutes; the administration of a loading dose and a 24-hour infusion is almost never followed by a recurrence of pain, and this regimen was proposed as the dosage schedule of ketoprofen to treat renal colic.

A simple fluorescence high-performance liquid chromatographic assay for dihydroquinidine in serum.

A simple and rapid reversed-phase C-18 high-performance liquid chromatography (HPLC) assay without a prior extraction step for dihydroquinidine (HQD) in serum is described. The method is selective and useful for monitoring HQD and its presumed metabolites, quinidine (QD), N-oxide QD, 3-hydroxy QD (3-OHQD), and 10-11-diol QD. The detection limit for HQD was 0.2 +/- 0.1 mg/L, and the peak heights--concentration curve was linear between 0.5 and 10.0 mg/L. The coefficients of variation within and between runs were identical, 5.0 +/- 1.5%. A 100 +/- 2.5% recovery was obtained by direct injection into the chromatograph of the supernatant following acetonitrile protein precipitation. The total assay time was less than 15 min.