We have examined the effect of HU 210, a synthetic cannabinoid receptor agonist, on rat body weight and eating behaviour. HU 210 (25, 50 or 100μ kg −1 ) sub-chronically administered for four days, produced a dose- and time-dependent loss of body weight. At the highest dose the body weight was not regained by the seventh day after the drug was stopped, remaining markedly below that of vehicle-treated animals. Atchuand sub-chronic treatment of fasted rats with HU 210 (50 and 100μ kg −1 ) significantly inhibited standard food intake; this anorexic effect was still present seven days after the last injection of 100μ kg −1 HU 210. Fasted rats, familiarized with chocolate and acutely treated with HU 210 at 50 or 100μ kg −1 reduced their standard food but not chocolate consumption in a two-choice condition. The results showed that HU 210 exerted a potent and long-lasting reduction of body weight, and that it produced a disrupting effect on the consumption of standard food, but not of chocolate.
γ-Glutamyl transpeptidase (γ-GTP) is known to play a vital role in the turnover of glutathione and protein synthesis. Hence, it is presumed that changes in the activity of γ-GTP in inflamed tissue itself might occur as both catabolic and anabolic processes are activated simultaneously in inflammation. The aim of this study was to determine γ-GTP activity in oedematous and granulomatous tissues in carrageenin-induced hind-paw oedema and cotton-pellet granuloma, respectively, in rats. In the time course study, maximum γ-GTP activity was observed in oedematous tissue at 4h after carrageenin injection and in granulomatous tissue on Day 7 after cotton-pellet implantation. Treatment with 6-MFA significantly inhibited the increase in γ-GTP activity in both oedematous and granulomatous tissues. The results suggest that the measurement of γ-GTP activity in inflammation may serve as a sensitive biochemical marker for evaluation of the in-vivo anti-inflammatory activity of drugs.
The effect of the histamine H2 receptor antagonist, ranitidine, on plasma concentrations of acetaminophen was investigated with respect to hepatic metabolism, in five volunteers. Acetaminophen (1000 mg) together with ranitidine (300 mg), placebo or at 1 h after ranitidine (300 mg) was orally administered to five healthy male volunteers. Venous blood samples were taken before and after drug administration. Plasma acetaminophen and acetaminophen conjugates (glucuronide and sulphate) were determined by HPLC. The pharmacokinetic parameters were calculated from the plasma acetaminophen concentration-time curves from each volunteer. The area under the plasma acetaminophen concentration-time curve from 0 to 3 h (AUC0–3) significantly (P < 0.01) increased from 13.03 ± 0.84 μg h mL−1 (placebo coadministration) to 21.30 ± 0.60 μg h mL−1 (ranitidine coadministration). The peak plasma acetaminophen concentration significantly (P < 0.01) increased from 18.30 ± 2.26 μg mL−1 (placebo coadministration) to 34.14 ± 1.07 μg mL−1 (ranitidine coadministration) 30 min after administration. Plasma acetaminophen concentrations with ranitidine were significantly increased at 15 to 120 min compared with placebo. Plasma acetaminophen glucuronide conjugate concentrations with ranitidine were significantly decreased at 15 to 45 min compared with placebo, whereas plasma acetaminophen sulphate conjugate concentrations were not significantly altered. Plasma acetaminophen and acetaminophen conjugate concentrations were not significantly different between placebo-coadministration and in the case where acetaminophen was orally administered 1 h after ranitidine. Coadministration of acetaminophen and ranitidine reduced plasma acetaminophen glucuronide concentrations and significantly increased plasma acetaminophen concentrations. The effects of ranitidine are as a result of the prevention of first-pass hepatic metabolism, by prevention of acetaminophen glucuronyltransferase. Thus care must be taken when acetaminophen and ranitidine are coadministered.
This study was aimed at enhancing the antitumour efficacy of bleomycin by encapsulating it in temperature-sensitive liposomes and using it in combination with localized hyperthermia of tumours for targeted delivery. Large unilammelar vesicles (LUV) made of synthetic lipids (disteroyl phosphatidylcholine and dipalmitoyl phosphatidylcholine) showing gel-to-liquid phase transition at 41°C, were used to encapsulate bleomycin. Comparison of LUV when incubated in saline at various temperatures revealed that maximum drug release (80%) occurred at 42°C compared with less than 5% release at 37°C. Better stability during storage was also observed with thermosensitive bleomycin liposomes. When administered intravenously to C57BL/6J mice bearing melanoma B16F1 tumour at 10 mg kg−1 dose, liposomal bleomycin in combination with hyperthermia (43°C, 30 min or 1 h) exhibited improved anticancer activity as evident by the enhanced volume doubling time and growth delay compared with animals treated with an equivalent dose of free bleomycin with or without hyperthermia. The results suggest that hyperthermia in combination with bleomycin encapsulated in temperature sensitive liposomes may be a useful targeted drug delivery system for more effective management of melanoma B16F1.
The effect of Withania somnifera Linn. Dunal (Solanaceae) on adjuvant arthritic rats was studied and compared with that of indomethacin. These results indicate that Withania somnifera has promising anti-arthritic activity as a result of its stabilizing action on lysosomal enzyme activity. The anti-inflammatory activity of Withania somnifera was assessed by measuring paw swelling and lysosomal enzyme activity in control and experimental rats. Increased paw diameter and lysosomal enzyme activity in the arthritic animals were significantly suppressed to near normal levels in rats treated with 1000 mg kg−1Withania somnifera root powder and 3 mg kg−1 indomethacin.
Six new ester derivatives of γ-(4-substituted piperazinyl)-α-phenyl propanol were prepared by esterification of the γ-piperazinyl propanols. The derivatives were methyl, ethyl, phenyl and benzyl esters, and they were obtained in good yields using a solid-liquid phase transfer catalysed esterification method. The nitrogen content of the new derivatives was also determined. Studies using isolated guineapig ileum showed that the derivatives possessed varying degrees of antispasmodic activity. Of the compounds evaluated, the ethyl ester of γ-(4-benzyl piperazin-1-yl)-α-phenyl propanol showed the greatest antispasmodic activity.
Hydroxypropyl methylcellulose (HPMC) K4M gels containing free flucinolone acetonide, liposomal-encapsulated flucinolone acetonide and physical mixture of the drug and lipids were prepared and evaluated in in-vitro drug release studies using rat skin to determine diffusion parameters. Data were analysed to calculate the quantity of the drug remaining in the skin (Qm) and in the blood (Csf) and the ratio of Qm to Csf. The in-vivo skin blanching assay performed with these formulations in human volunteers showed low blanching scores for liposomal gel formulations indicating low absorption of the liposomal-encapsulated drug into the blood stream and leading to the accumulation of the drug in the skin. This result is in agreement with the high Qm/Csf ratios obtained in the in-vitro experiments. Of all the formulations, gels containing liposomal-encapsulated flucinolone acetonide, prepared with drug, phosphatidyl choline and cholesterol in the ratio of 4:8:1, had the highest Qm/Csf ratio and minimum blanching score. The results indicate the potential of topical preparations containing liposomal-encapsulated drugs for selective accumulation of the drug in the skin.
Although much research has been completed on the application of matrix-assisted laser-desorption/ionization mass spectrometry (MALDI-MS) to the analysis of bacteria, no definitive studies have yet been performed on the analysis of fungi. Preliminary studies on the application of the MALDI-MS methodology, previously developed for the analysis of bacteria, to the analysis of intact fungal spores are described here. MALDI-MS and electrospray mass Spectrometry enable the analysis of high molecular-weight proteins, glycoproteins, oligosaccharides and oligonucleotides. Using MALDI-MS with bacteria has enabled the production of ‘fingerprints» of the intact cells; the ions observed are associated with the proteinaceous components of the cell wall. This study reports the adaptation of this technique to the direct analysis of fungal cells. Because of the large amount of carbohydrate in the fungal cell wall, the ions observed in the mass spectrometric experiments might be of carbohydrate origin. Penicillium spp., Scytalidium dimidiatum and Trichophyton rubrum have been studied in this preliminary investigation and all furnish individually distinctive spectra which seem to provide a profile of the cellular material with discrete peaks being observed over the mass range 2 to 13 kDa. The spectra obtained are reproducible within the method used but, as shown in our previous studies on bacteria, washing might selectively release components from the fungal cell wall.
Plants belonging to the Amaryllidaceae family have been shown to be a good source of biologically active alkaloids. The effect of 20 Amaryllidaceae alkaloids on the blood pressure of normotensive rats was assessed. The compounds evaluated belong to the lycorine, homolycorine, galanthamine, crinane, tazettine and miscellaneous skeletal types. At 1.5 mgkg−1, eight of the alkaloids assayed showed a significant effect on the arterial pressure of normotensive rats. Seven elicited a hypotensive response > 20%, with a lasting time ranging from 2.0 to 36.0 min while crinamine showed a hypertensive effect. These findings support the potential of Amaryllidaceae alkaloids as hypotensive drugs.
We isolated ophiobolin A from the f-7438 fungus strain. In the L1210 cell line, ophiobolin A (0-01-1 μM) showed cytotoxicity in a concentration-dependent manner. Morphological observations revealed that ophiobolin A (1 μM) induced shrinkage in cell soma and chromatin condensation, suggesting apoptotic cell death. Moreover, in DNA gel electrophoretic experiments, a typical apoptotic DNA ladder pattern was observed after treatment with this compound. The flow cytometric experiment indicated that ophiobolin A (0.01-1 μM) caused a concentration-dependent apoptosis in close agreement with concentrations that induced cytotoxicity in L1210 cells. The results suggested that ophiobolin A caused the death of L1210 cells through the apoptotic process. Ophiobolin A may become a powerful pharmacological tool for studying the apoptotic mechanism.
The aim of this study was to synthesize an ester with low lipophilicity, and to use this ester to further investigate pre-absorptive pulmonary first-pass metabolism. Hexanoic acid phenethyl ester was synthesized by reacting 2-phenylethanol with hexanoyl chloride. Pre-absorptive first-pass metabolism was assessed by comparing the areas under the blood concentration-time curves after intra-arterial administration of the hexanoic acid phenethyl ester with those after intratracheal instillation. Hexanoic acid phenethyl ester experienced extensive first-pass metabolism (53% of the absorbed dose) before or during absorption. This and earlier data suggests that the extent of this first-pass extraction is dependent on the physicochemical properties of the ester and in particular whether a compound experiences diffusion-limited absorption. Pre-absorptive pulmonary first-pass metabolism of compounds whose absorption is diffusion-rate limited may be extensive even when pulmonary enzyme expression is low. This has consequences for the systemic delivery of drugs and in particular esters via the lungs.
The relationship between histamine H2-antagonist pharmacokinetic behaviour and the response of intragastric pH to physiological stress, and vital support measurements, have been prospectively evaluated in ten critically ill patients of mean (± s.d.) age 61 ± 16 years, mean weight 60 ± 9.7 kg, and APACHE (acute physiology and chronic health evaluation) II score 10 ± 6. In this double-blind, cross-over study patients received either a continuous ranitidine infusion made locally by Chimi-Darou, Iran (study drug) or Zantac (control drug). Subjects were randomized to receive 6.25 mg h−1 of the study drug for 24 h during the initial phase, after which drugs were switched for the next 24 h. The two phases of the study were separated by a wash-out period of 16 h. Intragastric pH was measured for 72 h with an antimony pH probe catheter. Concentrations of ranitidine in plasma and gastric juice were determined by HPLC. Mean ± s.e.m. gastric pH was 4.47 ± 0.65 for patients receiving the locally made study drug and 4.25 ± 0.69 for those receiving Zantac (P=0.5351). There was good correlation between intragastric pH and plasma ranitidine concentration (r=0.97, P=0.0055 and r=0.94, P=0.169 for study and control drugs, respectively). Ranitidine was also present in significant quantities in the gastric juice. There was no correlation between intragastric pH and gastric concentration of ranitidine (r=0.37, P=0.6142) for the control drug nor between the concentrations of the drug in the gastric juice and plasma (r=0.055, P=0.9292). There was no correlation between median pH and APACHE II score or Glasgow coma scale (GCS) score (P=0.557 and P=0.541, respectively).
The inhibitory effects of nicardipine, nifedipine and itraconazole on P-glycoprotein-mediated transport of [3H]digoxin were examined using LLC-PK1 and LLC-GA5-COL150 cells, a porcine kidney epithelial LLC-PK1 cell line transformed with MDRI cDNA from man which results in overexpression of P-glycoprotein on the apical membrane. Basal-to-apical transport of [3H]digoxin in LLC-GA5-COL150 cells was higher than in LLC-PK1 cells; apical-to-basal transport was markedly lower in LLC-PK1 cells and even lower in LLC-GA5-COL150 cells. This is consistent with the possibility that [3H]digoxin is transported by P-glycoprotein. Co-administration of nicardipine or itraconazole markedly inhibited the basal-to-apical transport of [3H]digoxin in LLC-GA5-COL150 cells, and apical-to-basal transport also increased. The effect of nifedipine was less marked than that of nicardipine or itraconazole. Intracellular accumulation of [3H]digoxin after apical application in LLC-GA5-COL150 cells was 2.3 times less than in LLC-PK1 cells, and was increased by the addition of nicardipine or itraconazole, consistent with their inhibitory effects on transcellular transport. Following basal application of [3H]digoxin, its intracellular accumulation in LLC-GA5-COL150 cells was, unexpectedly, comparable with that in LLC-PK1 cells, and was hardly affected by the addition of nicardipine or itraconazole. In conclusion, it has been shown that nicardipine and itraconazole inhibited transport of digoxin, which is presumably mediated by P-glycoprotein. This explains their effects observed in clinical use.
The aim of this study was to determine the role of Rauwolfia serpentina root extract in the regulation of hyperthyroidism in mice. In L-thyroxine (50 μg/100 g for 30 days)-treated mice, an increase in serum concentrations of both thyroid hormones (thyroxine and triiodothyronine) and in hepatic glucose-6-phosphatase activity was observed. Daily administration of the plant extract (2.5 mg kg−1) either alone or with thyroxine for 30 days decreased concentrations of both thyroid hormones, indicating the possible regulation of hyperthyroidism by the plant extract. The plant extract also decreased hepatic lipid peroxidation and increased super-oxide dismutase and catalase activity in hyperthyroid mice without hepatotoxic effects. R. serpentina root extract might be a potentially effective treatment for hyperthyroidism.
A novel slotted-web transducer design concept for the measurement of die-wall stress in a compaction simulator has been developed and optimized by use of computer-aided design procedures. The optimized design was then built and tested. Geometric optimization of the novel design configuration and determination of strain-gauge placement were performed so that the transducer could withstand the high die-wall pressures encountered in a compaction simulator. Stress analysis was performed with Algor, a finite-element analysis software package. A model prototype was constructed with 4140 alloy steel and heat treated to a hardness of 43 Rockwell C. This prototype had a linear calibration curve (r2 = 0.99) at three different punch settings with no hysteresis. Radial stress versus axial stress transmission curves, and results from measurement of residual die-wall stress for dibasic calcium phosphate dihydrate, mannitol, sodium chloride, paracetamol and starch were consistent with literature data, which indicates satisfactory transducer performance.
This study was carried out to determine the extent of degradation of rifampicin, isoniazid and pyrazinamide from prepared mixtures and marketed preparations containing single, two, three and four drugs, under stomach conditions. Degradation studies were carried out in 0.1 M HC1 at 37°C for 50 min. A comparative study in simulated gastric fluid was also done. Under both conditions, rifampicin was decomposed by 17.8–24.4%, isoniazid to a lesser extent (3.2–4.7%), and pyrazinamide was stable. The decomposition of rifampicin was influenced by the presence of isoniazid but not by pyrazinamide or ethambutol. Compared with pure drugs and mixtures, wide variations in the decomposition of rifampicin (7.5–33.3%) and isoniazid (1.4–5.3%) were found in the marketed fixed-dose combinations, indicating the influence of formulation and storage conditions. The results suggest that the poor bioavailability of rifampicin might be in part due to the decomposition of the drug in the stomach. The recent WHO protocol suggests the comparison of the test fixed-dose combination preparations against a combination of separate formulations of two, three or four drugs. However, it may be more meaningful to carry out bioequivalence studies on fixed-dose combination formulations by comparing the test fixed-dose combination preparations with the standard formulations of individual drugs.
A HPLC method has been developed for determination of gliquidone in rat plasma. The assay involves combined extraction and precipitation with 1:1 methanol-acetonitrile, and separation of the analyte on a Shimpack ODS (C18) column with 75:25 (v/v) acetonitrile-0.1 M acetic acid as mobile phase. Detection at 229 nm was by photodiode-array detection. The assay was validated in accordance with international requirements and found to be specific, accurate and precise with a linearity range from 50 ng mL−1 to 10μg mL−1. The method was suitable for conducting pharmacokinetic studies in rats.
HNS-32 (N1N1-dimethyl-N2-(2-pyridylmethyl)-5-isopropyl-3,8-dimethylazulene-1-carbox-amidine) (CAS 186086-10-2) is a newly synthesized compound with an azulene structure within the molecule. The coronary relaxant action of HNS-32 was investigated pharmaco-mechanically on isolated pig coronary artery. The effects of HNS-32 were compared with diltiazem, a Ca2+-channel blocker. HNS-32 inhibited sustained contractions evoked by high KCl, prostaglandin F2α, a thromboxane A2 mimetic (U46619) and endothelin-1 in a concentration-dependent manner. The potency of HNS-32 to inhibit these contractions was 5- to 40-times lower than diltiazem. HNS-32 also diminished phasic contractions induced by acetylcholine, histamine and 5-hydroxytryptamine. Addition of excess Ca2+ counteracted HNS-32-induced inhibition of high KCl-induced contraction only by approximately 10% whereas it restored diltiazem-induced inhibition by about 50%. Suppression of the contractile response to a phorbol ester (phorbol 12,13-dibutyrate) by HNS-32 was approximately 40%. HNS-32 prevents coronary contractions produced by a wide variety of spasmogens. Although inhibitions of L-type Ca2+ channels and protein kinase C may be partly responsible for HNS-32 action, some direct action on the contractile systems seems to be involved in the coronary relaxation by HNS-32.
The poor bioavailability of rifampicin from fixed-dose combinations containing isoniazid has been attributed to isoniazid-catalysed degradation under acid conditions in the stomach. The mechanism by which isoniazid enhances rifampicin degradation is not known. The aim of this study was to determine the role of isoniazid in rifampicin decomposition. Degradation studies were performed in 0.1 M HCl at 37°, in absence and presence of isoniazid. Both rifampicin and isoniazid were analysed. The degradation of rifampicin was increased approximately threefold in the presence of isoniazid. Isoniazid itself was degraded to a lesser extent amounting to one-fifth of the fall of rifampicin. HPLC studies revealed that decomposition of rifampicin in acidic conditions in the absence of isoniazid stopped at the formation of 3-formylrifamycin, while the reaction in the presence of isoniazid proceeded to form a hydrazone between 3-formylrifamycin and isoniazid. The existence of hydrazone was confirmed by its isolation on a preparative column and comparison with an authentic sample synthesized from reaction of 3-formylrifamycin with isoniazid. We suggest that once 3-formylrifamycin is formed, it interacts with isoniazid to form the hydrazone, through a fast second-order reaction. As hydrazones are unstable in acid conditions, 3-formylrifamycin and isoniazid are regenerated in a reversible manner through a slower first-order reaction. In this complex reaction process, rifampicin is further degraded, while isoniazid is recovered.
In the light of current debate on cannabis “as a licensed drug”, this paper takes a balanced view of its potential therapeutic uses and its side-effect profile. In some medical conditions the use of cannabis seems to be beneficial to man. Despite some utility, the drug is not free from potential harm on the brain, lungs, immune and reproductive systems. One perspective would be the development of potent and selective cannabis-like drugs whose actions would be devoid of any negative effects.
