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PubMed1990

Voltammetric assay of heroin in illicit dosage forms.

The oxidation of heroin on a carbon paste electrode has been studied by using voltammetric techniques under both semi-infinite linear diffusion and hydrodynamic conditions. By employing a simple and rapid in situ pre-treatment of the electrode, excellent reproducibility of the current signal was obtained. Subsequently, the current was measured and the concentration of total heroin present could be determined. The method compared favourably with instrumental methods that are more commonly used for the quantification of heroin in clinical laboratories such as chromatographic, spectrophotometric or radiometric techniques. Moreover, the proposed method showed good selectivity and was superior with respect to cost and time of analysis, permitting the determination of heroin in seized drug samples over a wide concentration range.

Chemical Phenomena↗
PubMed2004

Pharmacokinetic evaluation of a new oral sustained release dosage form of tramadol.

AIMS: To compare the pharmacokinetic profile of a new modified release formulation of tramadol (Tramadol LP 200 mg, SMB Technology, Marche-en-Famenne, Belgium) with that of an immediate release capsule (Topalgic) 50 mg, Grünenthal, Aachen, Germany) after single and multiple dosing and to assess the potential effect of food on its relative bioavailability. METHODS: The first study had an open, single-dose, three-treatment, three-period, six-sequence, randomised, crossover design with at least a five-day wash-out. The second study had an open, steady-state, two-treatment, two-period, two-sequence, randomised crossover design with at least a seven-day wash-out. Both studies contained 30 healthy subjects. Both enantiomers of tramadol and O-demethyl-tramadol (the only active metabolite of tramadol) were assayed in the plasma using an LC-MS/MS method. AUC infinity, AUCt, Cmax, Tmax, and T1/2 were estimated. Statistical analysis was performed using univariate anova, the Wilcoxon nonparametric method or Friedman's nonparametric anova where appropriate. RESULTS: Tramadol had a significantly lower Cmax and longer Tmax than the conventional formulation. Thus, the mean (+/- sd) Cmax of tramadol were 646 +/- 192 and 300 +/- 94 ng ml-1 for Topalgic 4 x 50mg and Tramadol LP 200 mg, respectively (95% confidence interval on the difference expressed as a percentage 42-51). AUC of tramadol from both formulations was comparable (similar AUC infinity and AUCt). Thus, the mean AUC infinity of (+/-)tramadol obtained after multiple dosing were 4611 +/- 1944 and 5105 +/- 2101 ngh ml-1 after Topalgic 4 x 50mg and Tramadol LP 200 mg, respectively (95%CI 102-123%). We also demonstrate that the pharmacokinetics of the drug are not influenced by the intake of food. Thus, the mean AUC infinity of (+/-) tramadol were 5444 +/- 1637 and 5169 +/- 1580 ngh ml-1 after Tramadol LP 200 mg given in the fasting and fed states, respectively (95%CI = 88-103%). CONCLUSIONS: The new sustained release form of tramadol exhibits adequate properties for once a day administration. Furthermore, its pharmacokinetic profile is not affected by the intake of food.

Administration, Oral↗
PubMed2001

Determination of the antiepileptics vigabatrin and gabapentin in dosage forms and biological fluids using Hantzsch reaction.

A selective and sensitive method was developed for the determination of the anticonvulsants vigabatrin (I) (CAS 60643-86-9) and gabapentin (II) (CAS 60142-96-3). The method is based on the condensation of the drugs through their amino groups with acetylacetone and formaldehyde according to Hantzsch reaction yeilding the highly fluorescent dihydropyridine derivatives. The yellowish-orange color was also measured spectrophotometrically at 410 nm and 415 nm for I and II, respectively. The absorbance-concentration plots were rectilinear over the ranges 10-70 micrograms/ml and 20-140 micrograms/ml for I and II, respectively. As for the fluorescence-concentration plots, they were linear over the ranges 0.5-10 micrograms/ml and 2.5-20 micrograms/ml with minimum detection limits (S/N = 2) of 0.05 microgram/ml (approximately 2.1 x 10(-8) mol/l) and 0.1 microgram/ml (approximately 5.8 x 10(-7) mol/l) for I and II, respectively. The spectrophotometric method was applied to the determination of I and II in their tablets. The percentage recoveries +/- SD (n = 6) were 99.45 +/- 0.13 and 98.05 +/- 0.53, respectively. The spectrofluorimetric method was successfully applied to the determination of I and II in spiked human urine and plasma. The % recoveries +/- SD (n = 5) were 98.77 +/- 0.29 and 98.39 +/- 0.53 for urine and 99.32 +/- 0.74 and 98.90 +/- 0.96 for plasma, for I and II, respectively. No interference was encountered with the co-administered drugs: valproic acid (CAS 99-66-1), diphenylhydantoin (CAS 57-41-0), phenobarbital (CAS 50-06-6), carbamazepine (CAS 298-46-4), clonazepam (CAS 1622-61-3), clobazam (CAS 22316-47-8) or cimetidine (CAS 51481-61-9). A proposal of the reaction pathway is suggested. The advantages of the proposed methods over existing method are discussed.

Acetates↗
PubMed2000

[Acute pancreatitis--adverse effect of 5-aminosalicylic acid (mesalazine) in various galenic dosage forms].

HISTORY AND ADMISSION FINDINGS: A 34-year-old woman, being treated with oral mesalazine for colitis, developed upper abdominal pain radiating to the back one week after the drug was started, but the symptoms quickly regressed after mesalazine had been discontinued. The patient was admitted about 15 months later because of watery diarrhoea and lower abdominal pain. Physical examination revealed dehydration and pain on pressure over the lower abdomen. INVESTIGATIONS: Coloscopy demonstrated Crohn's disease of the colon, more marked on the left. Laboratory tests indicated inflammatory disease. TREATMENT AND COURSE: During treatment with oral prednisone and mesalazine enema the diarrhoea and laboratory parameters of inflammatory disease regressed. But 10 days after the start of treatment the patient complained of upper abdominal pain radiating to the back. Amylase and lipase levels were, respectively, four and twelve times normal. Ultrasound demonstrated an enlarged head of the pancreas, while endoscopy of the oesophagus, stomach and duodenum was unremarkable. 3 days after prednisone and mesalazine had been discontinued the symptoms had regressed and laboratory tests were normal. The symptoms did not recur when prednisone was administered again. CONCLUSION: Mesalazine may cause an acute pancreatitis when given either orally or by rectal infusion.

Acute Disease↗
PubMed1990

[Comparative study of 2 dosage forms of liquid dimethicone for ultrasound premedication].

A double-blind study was carried out to compare the effects of a premedication with 4 x 500 mg dimethylpolysiloxane (DPS)/24 hours and with 2 x 500 mg/12 hours before abdominal ultrasonography. The investigations covered 13 abdominal regions in specified planes. The incidence of the unobscured presentation of the selected organs and organ sections per patient served as a basis for a sonography index. This index was 67%, without significant difference between the two groups. We believe that the optimal conditions for sonography are given when the patient is fasting and two 500 mg doses of DPS are administered, one in the evening before and one in the morning at the day of investigation.

Abdomen, Acute↗
PubMedDate not supplied

Water-soluble betamethasone-loaded poly(lactide-co-glycolide) hollow microparticles as a sustained release dosage form.

In this study, betamethasone disodium phosphate-loaded microparticles were fabricated for sustained release using poly(lactide-co-glycolide) (PLGA) by spray drying and emulsion solvent evaporation/extraction techniques. Encapsulation efficiencies ranged from 59-80% using a water-in-oil-in-oil (W/O/O) double emulsion technique and more than 90% for a spray-drying method were obtained. This was a significant improvement compared to fabrication by a water-in-oil-in-water (W/O/W) double emulsion process, which had an encapsulation efficiency of less than 15%. Multiple-phase and biphasic release profiles were observed for microparticles of PLGA 50/50 and PLGA of higher lactide contents, respectively. The PLGA 50/50 hollow microparticles fabricated using the W/O/O double emulsion technique provided a sustained release of betamethasone disodium phosphate over 3 weeks.

Betamethasone↗
PubMed2005

Characterization of the absorption of theophylline from immediate- and controlled-release dosage forms with a numerical approach using the in vitro dissolution-permeation process using caco-2 cells.

After oral administration, drug absorption rate is recognized to be dependent on two major factors: dissolution and intestinal cells permeability. Caco-2 monolayer cells have been largely used as a permeation study model. In this study, a numerical approach funded on an exponential first-order time relationship was tested to compare immediate- and controlled-release tablets of theophylline using a dissolution-permeation system. The dissolution performance using USP II paddle apparatus was coupled to the permeability studies investigated in Caco-2 cell monolayers. The dissolved samples were taken at different times; their pH and osmolarity were adjusted to render them suitable to Caco-2 permeability studies (osmolarity = 300 mosm, pH = 7.4). The experimental data show that the dissolution fits the exponential first-order relationship rate. The permeability values were in a range of 4.45 10(- 6)-5.28 10(- 6) cm/s, and percentages of absorbed drug dose were dependent on the fraction initially present in the donor compartment, indicating that absorption of theophylline was dissolution rate limited. Plotting experimental absorbed fractions (F(a)) against experimental dissolved fractions (F(d)) show that permeation is the rate-limiting step in drug absorption process in the extended release form of theophylline. Our results demonstrate a general agreement between observed F(a)/F(d) relationships and theoretical F(a)/F(d) relationships obtained with our approach funded on dissolution and permeation behavior. We concluded that the couple dissolution-caco-2 system could be a useful tool to characterize intestinal permeation for a new formulation of a drug compared with the conventional one.

Absorption↗
PubMed2006

A sustained release dosage form of acyclovir for buccal application: an experimental study in dogs.

Acyclovir is an antiviral agent and it has been particularly used for the treatment of herpes simplex infections. The treatment of infection in the oral cavity is often difficult, because of insufficient drug concentration in saliva when acyclovir is administered via the oral route in conventional tablet form for systemic uptake. Therefore, it was aimed to prepare a tablet for buccal administration and to investigate its effectiveness by performing in vitro and in vivo experiments.The solubility (1.559-4.584) and octanol/water partition coefficients ( - 2.176 to - 1.625) of the acyclovir were investigated at different pH conditions. A series of tablet formulations were prepared for buccal application and their dissolution properties were determined in artificial saliva medium. The effect of tablet ingredients on the release rate and mucoadhesion force was investigated. The dissolution properties of commercially available acyclovir tablets were also determined in the artificial gastric juice. Franz type diffusion cells were used to determine acyclovir penetration through buccal mucosa from prepared buccal tablets. Selected buccal tablets, commercial tablets and intravenous acyclovir solutions were administered to mongrel dogs and drug levels in the blood determined by HPLC.A pharmacokinetic model for buccal application was also developed and blood concentrations were calculated theoretically and compared with the experimental results. Prepared buccal tablets were found to be effective for the treatment of viral infections locally within the oral cavity and also for systemic treatment.

Administration, Oral↗