Pain-relieving properties of topically applied morphine on arterial leg ulcers: a pilot study.

OBJECTIVE: To assess whether topical morphine is pharmacologically effective in relieving pain from ulcers caused by arterial insufficiency and identify whether this effect is centrally or peripherally mediated. METHOD: The analgesic effect of a topically applied hydrogel containing 0.5% of morphine was evaluated in a double-blind, placebo-controlled, three-way crossover pilot study involving nine patients with painful arterial leg ulcers. All patients had a baseline pain intensity of at least 5 on a 10-point numeric rating scale. They received the following three treatments in random order: morphine hydrogel plus a subcutaneous (SC) placebo infusion; placebo gel plus a SC infusion of 5mg morphine over six hours and a placebo gel plus a SC placebo infusion. Each treatment lasted one day. Pain was assessed during the first 24 hours after application of the hydrogel and the start of the subcutaneous infusion. RESULTS: There was a statistically significant difference between average baseline pain scores and those reported during treatment, but this difference was not clinically relevant. The three treatments did not differ in terms of the pain relief provided. CONCLUSION: Topical morphine does not have a clinically relevant analgesic effect in patients with painful arterial leg ulcers. Further research should focus on ulcers of other aetiology.

Long-term sedation with propofol 60 mg ml(-1) vs. propofol 10 mg(-1) ml in critically ill, mechanically ventilated patients.

BACKGROUND: Hypertriglyceridaemia is the main cause of therapeutic failure during propofol use in long-term sedated mechanically ventilated patients. Propofol 60 mg ml(-1) has been developed to reduce fat and volume load for the critically ill patient. The purpose of the study was to compare the effectiveness of sedation, achievability of effective concentrations and the effects on serum lipid concentrations of propofol 60 mg ml(-1) vs. propofol 10 mg ml(-1) for long-term sedation in critically ill patients. METHODS: In this randomized, open, prospective study, 20 critically ill, mechanically ventilated patients who required sedation for a minimum of 48 h received propofol 60 mg ml(-1) or propofol 10 mg ml(-1) in doses as required during 2-5 days. RESULTS: No differences between propofol 60 mg ml(-1) and propofol 10 mg ml(-1) were observed in the effectiveness of sedation using the Ramsay Sedation score and the Subjective Sedation score, nor in relation to the propofol concentrations. Between the two groups, there were no significant differences in the daily propofol dose, number of daily infusion rate adjustments or need for additional sedatives. Mean serum triglyceride concentrations were higher in the propofol 10 mg ml(-1) group compared with the propofol 60 mg ml(-1) group [5.26 (3.19) vs. 3.22 (2.05) mmol l(-1), P > 0.05][mean (SD)]. Patients in the propofol 10 mg ml(-1) group received more fat from the propofol infusion than from the propofol 60 mg ml(-1) group [53.2 (29.6) vs. 10.0 (4.7) % compared with fat from nutrition, respectively]. A significant relationship was observed between the daily total fat dose and the serum triglyceride concentration (r2 = 0.32, P < 0.001), whereas there was no significant correlation between the daily propofol dose and the serum triglyceride concentration. CONCLUSION: Propofol 60 mg ml(-1) is a useful alternative to propofol 10 mg ml(-1) for the long-term sedation of critically ill patients. Sedation with propofol 60 mg ml(-1) reduces fat and volume load by 83%, which reduces the risk of hypertriglyceridaemia.

Pharmacokinetics and pharmacodynamics of propofol 6% SAZN versus propofol 1% SAZN and Diprivan-10 for short-term sedation following coronary artery bypass surgery.

OBJECTIVE: A new formulation of propofol 6% in Lipofundin MCT/LCT 10% (propofol 6% SAZN) has been developed in order to reduce the fat, emulsifier and volume load that is given during prolonged infusions of propofol. The pharmacokinetics, pharmacodynamics and safety characteristics of propofol 6% SAZN were investigated during a short-term infusion and compared with the commercially available product propofol 1% in Intralipid 10% (Diprivan-10) and propofol 1% in Lipofundin MCT/LCT 10% (propofol 1% SAZN). METHODS: In a randomised double-blind study, 24 male patients received a 5-h infusion of propofol at the rate of 1 mg/kg/h for sedation in the immediate postoperative period following coronary artery bypass surgery. RESULTS: The average pharmacokinetic parameter estimates of clearance (Cl), volume of distribution at steady state (Vd,ss), elimination half-life (t1/2,beta) and distribution half-life (t1/2,alpha) observed in the three groups were 28 +/- 1.1 ml/kg/min, 1.8 +/- 0.12 l/kg, 94 +/- 4.1 min and 3.1 +/- 0.26 min, respectively (mean +/- SEM, n = 24) and no significant differences were noted between the three formulations (P > 0.05). In one patient receiving propofol 6% SAZN, in two patients receiving propofol 1% SAZN and in three patients receiving Diprivan-10, the level of sedation was inadequate and additional sedative medication had to be given. In all other 18 patients, the level of sedation was adequate. The mean propofol concentration in these six inadequately sedated patients was lower than the adequately sedated patients (P = 0.015). The serum triglyceride concentrations were not significantly different between the groups studied. No adverse events occurred in any of the patients. CONCLUSIONS: The pharmacokinetics, pharmacodynamics and safety characteristics of propofol 6% SAZN are in good agreement with those of the 1% formulations. Propofol 6% SAZN therefore provides a useful alternative to the commercially available 1% formulation for short-term sedation in the intensive care unit. Expected advantages in long-term sedation of the 6% over 1% formulation are the subject of an ongoing study.

Pharmacokinetics, induction of anaesthesia and safety characteristics of propofol 6% SAZN vs propofol 1% SAZN and Diprivan-10 after bolus injection.

AIMS: In order to avoid the potential for elevated serum lipid levels as a consequence of long term sedation with propofol, a formulation of propofol 6% in Lipofundin(R) MCT/LCT 10% (Propofol 6% SAZN) has been developed. The pharmacokinetics, induction of anaesthesia and safety characteristics of this new formulation were investigated after bolus injection and were compared with the commercially available product (propofol 1% in Intralipid(R) 10%, Diprivan-10) and propofol 1% in Lipofundin(R) MCT/LCT 10% (Propofol 1% SAZN). METHODS: In a randomised double-blind study, 24 unpremedicated female patients received an induction dose of propofol of 2.5 mg kg-1 over 60 s which was followed by standardized balanced anaesthesia. The patients were randomized to receive propofol as Propofol 6% SAZN, Propofol 1% SAZN or Diprivan-10. RESULTS: For all formulations the pharmacokinetics were adequately described by a tri-exponential equation, as the propofol concentrations collected early after the injection suggested an additional initial more rapid phase. The average values for clearance (CL), volume of distribution at steady-state (Vd,ss ), elimination half-life (t1/2,z ) and distribution half-life (t1/2, lambda2) observed in the three groups were 32+/-1.5 ml kg-1 min-1, 2. 0+/-0.18 l kg-1, 95+/-5.6 min and 3.4+/-0.20 min, respectively (mean+/-s.e.mean, n=24) and no significant differences were noted between the three formulations (P >0.05). The half-life of the additional initial distribution phase (t1/2,lambda1 ) in all subjects ranged from 0.1 to 0.6 min. Anaesthesia was induced successfully and uneventfully in all cases, and the quality of induction was adequate in all 24 patients. The induction time did not vary between the three formulations and the average induction time observed in the three groups was 51+/-1.3 s which corresponded to an induction dose of propofol of 2.1+/-0.06 mg kg-1 (mean+/-s.e. mean, n=24). The percentage of patients reporting any pain on injection did not vary between the formulations and was 17% for the three groups. No postoperative phlebitis or other venous sequelae of the vein used for injection occurred in any of the patients at recovery of anaesthesia nor after 24 h. CONCLUSIONS: From the above results, we conclude that the alteration of the type of emulsion and the higher concentration of propofol in the new parenteral formulation of propofol does not affect the pharmacokinetics and induction characteristics of propofol, compared with the currently available product. Propofol 6% SAZN can be administered safely and has the advantage of a reduction of the load of fat and emulsifier which may be preferable when long term administration of propofol is required.

Influence of different fat emulsion-based intravenous formulations on the pharmacokinetics and pharmacodynamics of propofol.

PURPOSE: The influence of different intravenous formulations on the pharmacokinetics and pharmacodynamics of propofol was investigated using the effect on the EEG (11.5-30 Hz) as pharmacodynamic endpoint. METHODS: Propofol was administered as an intravenous bolus infusion (30 mg/kg in 5 min) or as a continuous infusion (150 mg/kg in 5 hours) in chronically instrumented male rats. Propofol was formulated as a 1% emulsion in an Intralipid 10%-like fat emulsion (Diprivan-10, D) or as a 1%- or 6% emulsion in Lipofundin MCT/LCT-10% (P1% and P6%, respectively). EEG was recorded continuously and arterial blood samples were collected serially for the determination of propofol concentrations using HPLC. RESULTS: Following bolus infusion, the pharmacokinetics of the various propofol emulsions could adequately be described by a two-compartmental pharmacokinetic model. The average values for clearance (Cl), volume of distribution at steady-state (Vd,ss) and terminal half-life (t1/2, lambda 2) were 107 +/- 4 ml/min/kg, 1.38 +/- 0.06 l/kg and 16 +/- 1 min, respectively (mean +/- S.E. n = 22). No significant differences were observed between the three propofol formulations. After continuous infusion these values were 112 +/- 11 ml/min/kg, 5.19 +/- 0.41 l/kg and 45 +/- 3 min, respectively (mean +/- S.E., n = 20) with again no statistically significant differences between the three propofol formulations. Comparison between the bolus- and the continuous infusion revealed a statistically significant difference for both Vd,ss and t1/2, lambda 2 (p < 0.05), whereas Cl remained unchanged. In all treatment groups infusion of propofol resulted in a burst-suppression type of EEG. A profound hysteresis loop was observed between blood concentrations and EEG effect for all formulations. The hysteresis was minimized by a semi-parametric method and resulted in a biphasic concentration-effect relationship of propofol that was described non-parametrically. For P6% a larger rate constant onset of drug effect (t1/2,keo) was observed compared to the other propofol formulations (p < 0.05). CONCLUSIONS: The pharmacokinetics and pharmacodynamics of propofol are not affected by to a large extent the type of emulsion nor by the concentration of propofol in the intravenous formulation.

Determination of propofol in low-volume samples by high-performance liquid chromatography with fluorescence detection.

In order to determine propofol in rat whole-blood samples of 50 microl, we developed a rapid, simple and reliable method which is characterized by precipitation of blood elements with acetonitrile and submission of the supernatant to HPLC analysis with fluorescence detection. The method described is linear from 0.4 to 40 mg/l and the relative standard deviations in this concentration range are less than 10%. The limit of quantification proved to be 0.4 mg/l. Blood constituents do not interfere with the assay.

The myth of the second prophylactic antibiotic dose in aortoiliac reconstructions.

OBJECTIVES: To determine whether a prophylactic second dose of antibiotics is justified when severe blood loss and/or prolonged operation time occurs during aortoiliac reconstructions. METHODS: We measured the cefuroxime concentration in venous blood serum and subcutaneous fat tissue of 30 patients who underwent elective aortoiliac reconstruction after a single intravenous dose of 1500 mg cefuroxime. RESULTS: The mean blood loss was 1912 ml (range 200-7000). The mean operation time was 212 min (range 70-330). The cefuroxime concentration in blood serum 30 min after the gift varied from 53.7-561.6 mg/l and during closure of the abdominal incision from 13.2-90.0 mg/l. Taking the minimum inhibitory concentration for Staphylococcus species as 1.0 mg/l, we found an adequate prophylactic serum cefuroxime concentration in all patients. There was a statistically significant correlation between serum cefuroxime concentration and blood loss (p = 0.01) and operation time (p = 0.0001). CONCLUSIONS: Although serum concentration of cefuroxime is greatly influenced by blood loss and operation time, a second dose of cefuroxime in aortoiliac reconstructions is not necessary if the operation is completed within 5.5 h and if perioperative blood loss does not exceed 7000 ml.

[Psychiatric symptoms due to theophylline overdose; the necessity of blood level monitoring]. / Psychische klachten door overdosering van theofylline; noodzakelijkheid van spiegelcontrole.

Two patients presented with severe side effects of theophylline. Due to the theophylline intoxication patient A developed ischaemic hepatitis, which made haemodialysis treatment necessary to accelerate the elimination of the drug from the body. The intoxication caused immobilisation and total dependence with respect to the daily activities of patient B. In neither case was the association between mood disorders--like depression, agitation and anxiety--and an overdose of theophylline recognised. Administration of theophylline should be monitored with regular measurements of the serum theophylline concentration, because of its narrow therapeutic margin and the serious toxic side effects.

Decomposition of pilocarpine eye drops assessed by a highly efficient high pressure liquid chromatographic method.

A rapid high-resolution high pressure liquid chromatographic method was developed for assaying pilocarpine. Pilocarpine in ophthalmic solutions decomposes fairly rapidly to give isopilocarpine, pilocarpic acid and isopilocarpic acid. The quality of an ophthalmic solution can be assessed by assaying these decomposition products. Existing high pressure liquid chromatographic methods suffer from long analysis times and poor resolution. The new method uses as the mobile phase 6 ml/l of triethylamine in water (pH 2.3, adjusted with 85% phosphoric acid) at a flow of 1.5 ml/min and as the stationary phase a C18-silica 125 x 4.6 mm column. 2-Amino-1-phenyl-1,3-propanediol is used as an internal standard. Complete separation was obtained within 8 min. Pilocarpine eye drops were stored under different conditions and then analysed for decomposition products. During heat treatment, decomposition to isopilocarpine predominated over decomposition to pilocarpic or isopilocarpic acid. However, when stored at room temperature or in a refrigerator, formation of pilocarpic acid clearly prevailed. Thus, from assessment of decomposition products, the cause of decomposition can be established.

Xenopus laevis skin Arg-Xaa-Val-Arg-Gly-endoprotease. A highly specific protease cleaving after a single arginine of a consensus sequence of peptide hormone precursors.

Comparison of the precursor sequence for several peptide hormones of Xenopus laevis skin revealed a consensus sequence around a single arginine cleavage site which is 100% conserved on four residues Arg-Xaa-Val-Arg-Gly (RXVRG). A tetradecapeptide substrate (Asp-Val-Asp-Glu-Arg-Asp-Val-Arg-Gly-Phe-Ala-Ser-Phe-Leu-NH2) was used as a probe to purify and characterize the putative processing endoprotease. A hydrophobic enzyme was purified at least 9000-fold from Xenopus skin exudate by a four-step procedure. This highly specific activity cleaves the Arg-Gly bond and has no effect on the Arg-Xaa bond. It was strongly inhibited by divalent ion chelators, moderately by phenylmethylsulfonyl fluoride, aprotinin, and 1-tosylamide-2-phenylethyl chloromethyl ketone, but was insensitive to soybean trypsin inhibitor. Tetradecapeptide derivatives selectively modified on each of the amino acids of the consensus sequence demonstrated the relevance of this conserved pattern to endoprotease action. This enzyme, which we refer to as RXVRG-endoprotease, is proposed to be involved in the post-translational processing of pro-caerulein, promagainin, pro-xenopsin, pro-glycyl-leucine amide, and pro-levitide of X. laevis skin secretory granules.

Characterization of a somatostatin-28 generating metallo-endoprotease from rat brain cytosol.

Brain cytosol contains a neutral metallo-protease of about 80,000 which cleaves a substrate containing the site at which mammalian prosomatostatin is cleaved to generate somatostatin 28 in vivo. This represents a cleavage on the carboxyl side of a single arginine residue at an Arg-Ser bond. The enzyme was unable to cleave several other substrates containing single arginine residues or two substrates containing an Arg-Lys or Lys-Arg pair. When it was incubated with anglerfish pancreatic prosomatostatin, it produced significant quantities of a peptide which co-eluted with somatostatin 28 II. Based on the ability of this enzyme to cleave small and large substrates related to somatostatin, it is a potential candidate for the enzymes which cleaves prosomatostatin in vivo.

Prosomatostatin processing in anglerfish brain, gut and pancreas.

The distribution of somatostatin immunoreactive forms in three tissues of the anglerfish (Lophius piscatorius L.) was analyzed by a combination of gel permeation, High Pressure Liquid Chromatography and amino acid analysis. The data indicate that prosomatostatins I and II are expressed in both neural and gastro-intestinal tissues and that their post-translational processing gives rise to somatostatin-14 I, somatostatin-28 II and to some of its hydroxylysine23-derivative, respectively. It is concluded that, in contrast to the mammals, production of two somatostatins in the Teleostean fish requires two structurally distinct precursors whose processing operates in a fixed pattern rather than in a tissue-specific manner.

Characterization of vasoactive intestinal peptide receptors by a photoaffinity label. Site-specific modification of vasoactive intestinal peptide by derivatization of the receptor-bound peptide.

The biological effects of vasoactive intestinal peptide (VIP) are mediated by binding to a membrane-bound receptor. Probes designed to trap this receptor by binding to it in a covalent way may suffer from a greatly reduced affinity. We report here, for the VIP receptor, the use of a photoaffinity probe obtained by derivatization of receptor-bound VIP with para-azidophenylglyoxal. This method protected the parts of the molecule essential for receptor binding. The VIP derivative thus obtained became covalently linked when irradiated. In the dark, however, it exhibited normal VIP-like behavior and retained its biological activity. This derivatization method might be generally applicable when hormone analogues have to be prepared without loss of receptor affinity. Receptor characterization studies on liver plasma membranes showed the presence of high- and low-affinity binding sites with KD = 0.1 and 5 nM, respectively. Treatment of membranes with dithiothreitol causes loss of high-affinity binding. The high-affinity site, trapped by the photoaffinity probe, resolved into two molecular mass forms, 50 and 200-250 kDa. Reduction of the receptor-probe complex left the 50-kDa form intact, whereas the amount of the 200-250-kDa form greatly diminished. We demonstrate the importance of the presence of disulfide bonds in one of the molecular forms involved in high-affinity binding.