[Influence of changes to daily dose of opioids on aspects of cognitive and psychomotor performance involved in driving]. / Einfluss von Anderungen der Opioidtagesdosis auf fahrrelevante kognitive und psychomotorische Leistungen.

INTRODUCTION: It has been shown that long-term treatment with opioids does not necessarily impair driving ability in patients suffering from chronic pain. However, few studies are so far available on how increases in daily opioid dosage affect driving ability. METHODS: A prospective trial was conducted in patients suffering from chronic noncancer pain, to examine the effects of the daily dose of opioids on psychomotor and cognitive functions. A computerized test system was administered to patients before and 7 days after alteration of their opioid therapy, to determine performance affecting driving ability at each time point. The test design was based on both international and national recommendations for the examination of driving safety. RESULTS: Raising the daily dose of opioids and/or changing to an opioid at a higher WHO level had no effect on the functions relevant to driving ability in the group context. Pain intensity and serum concentrations of morphine influenced only few items in the test battery. CONCLUSION: Seven days after an increase in the daily dose of an opioid or after the initiation of opioid therapy there was no general deterioration in patients' driving ability at group level.

Sensitive and convenient method for the quantification of clonidine in serum of pediatric patients using liquid chromatography/tandem mass spectrometry.

An improved and easy to use liquid chromatography/tandem mass spectrometric (LC/MS/MS) method in human serum was developed for the quantification of clonidine (CLD), an alpha2-/alpha1-adrenoceptor agonist, used for analgo-sedation and the therapy of opioid withdrawal in pediatric patients. Sample preparation consisted of precipitation of serum proteins by adding acetonitrile and centrifugation of the sample subsequently. [(2)H4]Clonidine (CLD4) served as internal standard. Chromatographic separation of the supernatant was achieved using a 100mmx3mm, 5microm Thermo Electron BetaBasic C4 column with isocratic flow and elution consisting of 0.1% formic acid/acetonitrile (85/15, v/v) and a flow-rate of 350microl/min resulting in a column pressure of 280-420kPa. LC/MS/MS detection was performed by using a triple-stage quadrupole mass spectrometer (TSQ Quantum, Thermo Electron) working in selected reaction monitoring mode with positive electrospray ionization. The analyte was quantified in a single run within 5min. Linearity was demonstrated over the expected concentration range 0.15-50microg/l CLD. The lower limit of quantification (LLOQ) and the limit of detection were 0.1microg/l and 0.01microg/l, respectively. None of the drugs used concomitantly during analgesic therapy interfered in the assay in vitro. Intra-day precision expressed as RSD was 9.6% or less for CLD, while inter-day result was 10.0% or less for CLD. Intra-day and inter-day accuracy was within +/-4.9% and +/-1.8%, respectively. The method was validated according to the international guidelines of the International Conference on Harmonisation (ICH) and the US Food and Drugs Administration (FDA). The described method is suitable to analyse serum samples with very small volumes and sets the stage for pharmacokinetic studies in pediatric studies.

Pharmacokinetics of intra-arterial mitomycin C in the chemoembolization treatment of liver metastases with polyvinylalcohol or degradable starch microspheres.

OBJECTIVES: In cancer treatment, arterial blood flow reduction by embolization combined with intra-arterial chemotherapy may be advantageous by achieving high and prolonged drug concentrations in the tumor, and lower systemic drug exposure. The pharmacokinetics of intra-arterial mitomycin C (MMC) was investigated in patients with liver metastases undergoing chemoembolization treatment. METHODS: The chemoembolization treatment consisted of the use of polyvinylalcohol microspheres (ITC-Contour, diameter 150-250 micro m, irreversible vessel occlusion, 20 mg MMC, 15 patients) followed by sealing of the supplying artery with Ethibloc. Alternatively, starch microspheres (Spherex, diameter 45 micro m, biologically degradable, 10 ml of suspension containing 60 mg starch/ml, 20 mg MMC in 7 patients, 15 mg/m2 body surface in 3 patients) were used. MMC was infused over 6 min into the artery supplying the tumor. Serum MMC concentrations were determined from peripheral venous blood samples [protein precipitation with acetonitrile, reverse-phase HPLC with ultraviolet detection (C18 column, elution with 0.01 M, pH 6.5 phosphate buffer/methanol, v/v 70:30, 365 nm)]. The pharmacokinetic parameters were computed assuming an open two-compartment model and linear kinetics. RESULTS: The disposition parameters for MMC in patients treated with polyvinylalcohol microspheres were comparable to data from the literature (C(max)=913+/-98 ng/ml, T(max)=7.7+/-0.3 min, V(c)=0.27+/-0.03 l/kg, V(ss)=0.59+/-0.07 l/kg, Cl=757+/-67 ml/min, T(1/2 alpha)=5.8+/-0.8 min, T(1/2 beta)=50.4+/-4.1 min). There was no significant difference in the disposition parameters for MMC between patients treated with polyvinylalcohol microspheres and those treated with starch microspheres ( P>0.05). In particular, there was no significant difference in the standardized AUC between the groups; this implies that the systemic toxicity of MMC is comparable when polyvinylalcohol microspheres and ethibloc (AUC 1472+/-123 microg min/l per 1 mg MMC) or starch microspheres (AUC: 1448+/-172 microg min/l per 1 mg MMC) are used. CONCLUSION: The AUC values found in this study do not indicate a reduction in the systemic toxicity of MMC if applied intra-arterially in combination with embolizing microspheres, when compared to the AUC values in the literature for intra-arterial application without embolization, or intravenous MMC application. The amount of starch microspheres may have been too small to cause marked effects. On the other hand, there is a very wide range of AUC values reported in the literature for different application modes, and the use of such historical controls is not adequate for detecting more subtle advantages of the chemoembolization procedure, which may, however, exist.

Morphologic proof of the toxicity of mitomycin C on the ciliary body in relation to different application methods.

BACKGROUND: Since postoperative hypotony has been a frequent complication of glaucomatous filtration surgery with adjunctive use of mitomycin C (MMC), the question arises of whether there may be another application method which can minimize this side effect. The purpose of this study was to establish the morphologic side effects of different application methods. METHODS: MMC 0.2 mg/ml was applied to the episclera of nine eyes of six pigmental rabbits at random via collagen shield (CS), soft contact lens (CL), or lyophilisate (20 microg; LY) for 5 min. Two eyes (controls) had a subconjunctival injection of BSS only. Another control eye was left untreated (no injection). No trabeculectomy was performed. One hour later the amounts of MMC in the conjunctiva and aqueous were analyzed by reverse-phase high-pressure liquid chromatography. Ciliary bodies were dissected from the enucleated eyes, embedded and investigated by transmission electron microscopy (TEM). Cell height of the nonpigmented ciliary epithelium was morphometrically assessed by means of computer-assisted image analysis. RESULTS: The light-microscopic analysis of the sectioned cell area revealed reduction of the cell height of the non-pigmented ciliary epithelium (NPCE) after application with soft contact lens (fourfold) and collagen shield (2.5-fold) but not with lyophilisate compared to the untreated eye. The following ultrastructural changes were seen: loss of apical microvilli (CS, CL, LY), disintegrating melanin granules within NPCE (CS), lysis of entire areas with NPCE cells (CS), myelin figures within mitochondria (LY), intracellular vacuoles (CS, CL), lysis of myelinated nerves (CS), myelin figures in mitochondria of endothelial cells (LY), and lysis of stromal fibrocytes (CS). In the control eyes (injection of BSS) none of these ultrastructural changes were detected in the cylindrical NPCE cells. The concentration of mitomycin in the aqueous humor after topical application of MMC on the episclera for 5 min were all below the detection limit (<10 ng/ml). The concentration of MMC in the conjunctiva ranged from 2.1 to 3.7 microg/g. CONCLUSION: Severe morphologic alterations were seen at the electron-microscopic level after application of MMC 0.2 mg/ml with a collagen shield and with a soft contact lens. They were mildest with lyophilisate and absent in the BSS controls. A new administration device is needed if trabeculectomy is to be performed successfully using MMC in human glaucomatous eyes.

Pseudocholinesterase-activity reduction during cardiopulmonary bypass: the role of dilutional processes and pharmacological agents.

UNLABELLED: 1. Pseudocholinesterase (ChE) activity is a determinant of the elimination kinetics of several drugs used in anesthesia. The time course of ChE activity was investigated in 16 patients undergoing cardiosurgery for a cardiopulmonary bypass (CPB) in normothermia or hypothermia. 2. The onset of the CPB was accompanied by a decrease in ChE activity (-37%) (P<0.05) and protein concentration (-24%) (P<0.05). The quotient ChE activity/protein concentration was numerically reduced to a smaller extent (-15%) (P>0.05). After the CPB was finished, ChE activity and the protein concentration remained low for the remaining operation time. 3. There was no difference in ChE activity, measured in vitro at 37 degrees C, between the normothermic and hypothermic group (P>0.05). 4. There was no correlation between heparin concentration in serum and reduction of ChE activity in vitro (P>0.05). In vitro, the ChE activity was not affected by either heparin in doses as high as 10,000 U/ml or aprotinin in doses as high as 10,000 U/ml (P>0.05). 5. CONCLUSIONS: (1) ChE activity is reduced by CPB mainly by hemodilution and (2) the pharmacological agents used in the present anesthetic technique (heparin, aprotinin, midazolam, fentanyl, propofol and mivacurium) do not inhibit ChE activity at therapeutic serum concentrations.

Ocular concentrations of mitomycin C using different delivery devices.

Hypotony and its sequelae are a frequent complication of trabeculectomies performed with mitomycin C (MMC), possibly related to intraocular toxicity of the substance. In an animal model with rabbits, we used different devices for the application of MMC and measured extra- and intraocular concentrations by HPLC. In addition, the concentrations of MMC remaining in the devices were determined. The devices were (1) a regular surgical sponge, (2) a scleral shield, (3) a presoaked soft contact lens, (4) a soft contact lens with MMC application, and (5) subconjunctival injection. Ocular concentrations of MMC were similar within the first 4 groups and were highest in the last. The measurements suggest that MMC penetrates intraocularly regardless of the device used. The variability of remaining MMC concentrations in the devices was lowest in the soft contact lenses suggesting an improved delivery system compared to the usually used surgical sponges.

Caffeine in saliva after peroral intake: early sample collection as a possible source of error.

The influence of collection time on the correlation of caffeine concentrations in saliva and serum was examined in six healthy adults after peroral administration of 5 mg/kg caffeine citrate. Saliva was obtained from three different salivary glands (sublingual, right parotid, and left parotid) and evaluated separately. Caffeine concentrations in saliva and serum samples were determined by high-performance liquid chromatography. There were no differences in the caffeine concentrations in saliva from the three investigated glands (alpha = 0.05). Saliva samples collected earlier than 2 hours after caffeine intake showed higher caffeine concentrations than could be expected from the corresponding serum samples. Gingiva contamination was shown to be responsible for the higher caffeine concentrations in saliva, and it was concluded that saliva is a feasible matrix for therapeutic drug monitoring of caffeine. If caffeine is administered orally, saliva samples should be taken at least 2 hours after caffeine intake. If caffeine-containing beverages are used as the source of caffeine or if subjects do not cooperate by rinsing the mouth of caffeine contamination, an additional 60 minutes should be added before saliva sampling.

Sensitive and convenient high-performance liquid chromatographic method for the determination of mitomycin C in human plasma.

An improved high-performance liquid chromatographic assay for the cytostatic drug mitomycin C in plasma is presented. The principal steps are precipitation of plasma proteins with acetonitrile, lyophilization of the supernatant and reversed-phase chromatography on a Hypersil ODS 5 microm column with 0.01 M NaH2PO4 buffer (pH 6.5)-methanol (70:30, v/v) in isocratic mode. At a flow-rate of 1.3 ml/min a column pressure of 180-220 bar resulted. Porfiromycin served as internal standard. UV detection was performed at 365 nm. Quantitation limit based on a coefficient of variation <10% in intra- and inter-day assay was 5 microg/l mitomycin C, detection limit based on a signal-to-noise ratio of 3 was 1 microg/l. Recovery was 100% and linearity was shown for the whole range of concentration (1-500 microg/l). None of the five drugs used during chemoembolisation interfered with the assay in vitro. The assay meets the requirements for pharmacokinetic studies of mitomycin C in patients as regards sensitivity and ease of use.

Stereoselective high-performance liquid chromatographic assay with fluorometric detection of the three isomers of mivacurium and their cis- and trans-alcohol and ester metabolites in human plasma.

An improved high-performance liquid chromatography assay for the three stereoisomers of the muscle relaxant mivacurium and its metabolites in plasma is presented. The principal steps in the assay are precipitation of plasma proteins by acetonitrile, lyophilization of the supernatant and ion-exchange chromatography on Spherisorb 5-SCX column, with gradient elution (acetonitrile from 32 to 68% v/v and ionic gradient from 7 to 56 nmol l-1 Na2SO4), a flow-rate of 2.0 ml min-1, D-tubocurarine as internal standard and fluorometric detection (excitation wavelength = 280 nm, emission wavelength = 320 nm). Quantitation limit of cis-cis, cis-trans, trans-trans isomers were 0.003, 0.002 and 0.005 mumol l-1, respectively. Quantitation limits for the monoestercis metabolite were 0.011 mumol l-1, for the monoestertrans metabolite 0.017 mumol l-1, for the amino-alcoholtrans 0.020 mumol l-1 and for the amino-alcoholcis 0.021 mumol l-1. None of eight drugs used during anaesthesia interfered with the assay in vitro. Satisfactory performance was demonstrated by the measurement of the isomers and their metabolites in plasma of two patients over a 6-h period after repeated injections of mivacurium.

Pharmacokinetics of intraarterial mitomycin C in the chemoembolisation treatment of liver metastases.

1. The pharmacokinetics of mitomycin C (MMC) were investigated in 12 colorectal cancer patients with liver metastases undergoing chemoembolisation. Hepatic artery branches were embolized using polyvinylalcohol microspheres (150-250 microns) before applying 20 mg MMC in 4-8 min. 2. Serum MMC concentrations were determined from peripheral venous blood samples by reverse-phase HPLC using ultraviolet detection. Pharmacokinetic parameters were computed assuming an open two-compartment model. 3. Pharmacokinetic parameters were similar to values given in the literature for intravenous (IV) or intraarterial (IA) bolus MMC injections (Tmax = 7.0 min following the beginning of MMC infusion, Vss = 0.57 1/kg, C1 = 8.9 ml/min.kg, T1/2 alpha = 8.3 min, T1/2 beta = 58.6 min). 4. The area under the serum concentration-time-curve (AUC), standardized by the MMC amount injected, was similar to values reported in the literature for IV or IA bolus injections. There is no evidence for reduced systemic MMC exposure following the embolization procedure used.

Mitomycin-C concentration in human ocular aqueous humor after topical administration during trabeculectomy.

UNLABELLED: The concentration of the antitumor antibiotic mitomycin (CAS 50-07-7, mitomycin C, MMC), used in ophthalmic surgery for its antiproliferative effects, was measured in the aqueous humor of 7 glaucoma patients undergoing trabeculectomy. Sponges soaked with MMC-solution (100 microliters of MMC-solution 0.2 mg/ml: 20 micrograms) were applied intraoperatively on the scleral flap for 5 min. 100 to 200 microliters of aqueous humor were drawn with a needle 10 min following the end of topical MMC-treatment. Samples were assayed for MMC using a reverse-phase HPLC-system with ultraviolet detection (C18-column, elution: phosphate buffer (0.01 mol/l, pH: 6.5): methanol, v:v = 70:30, 365 nm). Swabs were extracted in phosphate-buffer (0.1 mol/l, pH: 7.0) before HPLC-analysis. External calibration was used for MMC quantitation. Quantitation limit was 10 ng/ml. In all aqueous humor samples MMC-concentration was below 10 ng/ml. MMC in the swabs amounted to 37% of the MMC amount applied. CONCLUSION: After intraoperative topical application, the MMC concentration in the aqueous humor of patients is very low. The substantial loss of MMC from the swabs used for the topical MMC-treatment suggests 1. rapid systemic absorption of MMC and/or 2. a loss through irrigation of the operative field following topical MMC-application.

Ketamine and strychnine treatment of an infant with nonketotic hyperglycinaemia.

UNLABELLED: Non-ketotic hyperglycinaemia (NKH) is a severe seizure disorder associated with high glycine levels. Glycine is a major inhibitory neurotransmitter in the CNS, but has also modulating effects at one of the glutamate receptors, the N-methyl-D-aspartate-(NMDA) receptor. Based on this knowledge we treated a female newborn suffering from severe NKH with the NMDA receptor blocker ketamine in association with strychnine and magnesium supplementation. This treatment led to cessation of seizures, reappearance of swallowing and sucking and improved the neurological status. Some pharmacokinetic data of strychnine and ketamine in the infant are given. CONCLUSION: Ketamine in combination with strychnine may be beneficial in non-ketotic hyperglycinaemia.

Effects of different inotropes with antioxidant properties on acute regional myocardial ischemia in isolated rabbit hearts.

1. The antiischemic properties of the flavonoids acetylvitexin-rhamnoside (AVR) and luteolin-7-glucoside-(LUT), combining phosphodiesterase (PDE)-inhibitory and antioxidant properties, were studied in comparison to amrinone (AMR) or superoxide dismutase (SOD). The effects of the new dihydropyridine-type calcium-agonist Bay T 5006 were studied in comparison to Bay K 8644. 2. In isolated Langendorff-rabbit hearts perfused at constant pressure, acute regional ischemia (MI) was induced by coronary artery occlusion (CAO) and quantitated from epicardial NADH-fluorescence photography. Drugs were applied either before or after CAO (pre-treatment or treatment) to permit distinguishing the influence of functional and direct cytoprotective actions in the poorly collateralized rabbit hearts. 3. SOD did not affect left ventricular pressure (LVP) or coronary flow (CF) and reduced MI only if applied before CAO. LVP and CF were enhanced by LUT or AMR but not by AVR. MI was reduced to a similar extent in hearts treated with either drug. Cardioprotection by LUT was not improved by starting drug application before CAO. 4. Bay K 8644 reduced LVP and particularly CF, whereas Bay T 5006 did not affect functional parameters. MI was enlarged by Bay K 8644 and remained unaffected by treatment or pretreatment with Bay T 5006. 5. AMR, LUT and AVR possess antiischemic properties related to an improvement of myocardial perfusion. Although oxygen free radicals contribute to ischemic tissue injury, as shown by the cardioprotective effectiveness of SOD, antioxidant properties of the flavonoids LUT and AVR do not seem to be relevant for the antiischemic effects. Our findings also give no evidence for antioxidant properties of dihydropyridines relevant for cardioprotection.

Alcuronium: a pharmacodynamic and pharmacokinetic update.

Alcuronium may be considered a muscle relaxant of historical rather than clinical significance. However, recent information from the manufacturer revealed its persisting clinical use in 26 countries worldwide. Thus, a pharmacodynamic-pharmacokinetic update appears mandatory. An intravenous (IV) single-bolus injection of alcuronium (0.25 mg/kg = ED95) was administered to 10 patients undergoing maxillofacial surgery during nitrous-oxide opioid anesthesia. Alcuronium neuromuscular block (evoked twitch tension), plasma concentration, and renal elimination (high-performance liquid chromatography [HPLC] assay) were measured during the 12-h after its administration. The time of onset, the time from end of injection to recovery to 25% of control twitch tension (DUR25%), and the recovery index were 2.2 +/- 1.2, 54 +/- 14, and 37 +/- 11 min, respectively (mean +/- SD). Two hours after the injection of alcuronium, partial recovery from the neuromuscular block had occurred from 100% to 26% +/- 24% depression of twitch tension, although less than 25% of the injected dose was recovered from the urine. The 12-h plasma concentration and urinary recovery were 0.1 +/- 0.08 mg/L (one-sixth of the 50% inhibitory concentration) and 61% +/- 20%, respectively. Recovery from neuromuscular block was dominated by intercompartmental distribution rather than by renal elimination. Since alcuronium does not undergo biodegradation, our data may serv as a reference for the complex pharmacokinetics of readily metabolized modern muscle relaxants. The long plasma half-life with slow excretion merits attention with respect to the erroneous original perception that alcuronium was an intermediate-acting muscle relaxant.

Ocular concentrations of mitomycin C after extraocular application in rabbits.

To determine the intraocular concentrations of Mitomycin C (MMC) after extraocular application, we used pigmented rabbits and placed sponges soaked with MMC under the conjunctiva on top of the intact episclera. First, we soaked the sponges with volumes ranging from 0.025 ml to 0.3 ml of the solution containing MMC and sampled aqueous humour after 30 minutes. The concentrations, as determined by high performance liquid chromatography, did not correlate to the amount of MMC given. Then, we soaked the sponges with different concentrations of MMC with a volume of 0.1 ml and sampled aqueous humour, vitreous humour and sclera after 60 minutes. The concentrations of MMC were higher in the vitreous than in the aqueous, and, relative to these values, very high in the sclera. These results indicate that the amount of MMC reaching the interior of the eye after standard extraocular application may be highly variable, and that the concentrations of MMC in the sclera and formed vitreous can be considerably higher than in the aqueous humour.

The pathophysiology of cocaine cardiotoxicity.

Cocaine use is accompanied by a high risk of serious adverse effects involving the cardiovascular system. The basic cellular mechanisms of cocaine consist in [1] a potentiation of catecholamine effects by inhibition of the presynaptic uptake carrier [2] local anesthetic effects by the block of sodium-channels. Acute ischemic events can be induced by cocaine through coronary spasms in a situation of physiologic stress already accompanied by an enhanced myocardial oxygen demand. Procoagulant properties of cocaine may, moreover, favor coronary thrombosis formation and the development of myocardial infarction. Ischemia, reperfusion and the direct action of catecholamines on cardiocytes are accompanied by enhanced cytoplasmic calcium levels, inducing delayed after-potentials, repetitive action-potential generation and premature ventricular beats. Conduction velocity impairments caused by the local anesthetic effects of cocaine and inhomogeneous repolarization phenomena related to potassium channel inhibition may form a substrate for re-entrant circuits inducing ventricular fibrillation. Cocaine abuse may also cause degenerative and inflammatory alterations of the myocardium. Besides secondary ischemic changes, hypersensitivity-myocarditis and toxic cardiomyopathies that may be due to the cardiotoxic effects of catecholamines have been described in cocaine abusers. Moreover, persons using cocaine intravenously seem to be particularly endangered by bacterial endocarditis compared to the users of other intravenous drugs, for still unknown reasons.

Functional and antiischemic effects of luteolin-7-glucoside in isolated rabbit hearts.

1. The functional effects of the flavonoid luteolin-7-glucoside (LUT) were investigated in Langendorff-rabbit hearts perfused at constant pressure. Repetitive myocardial ischemia was induced by coronary artery ligature and quantified from NADH-fluorescence photography. 2. LUT significantly enhanced left ventricular pressure and the global and relative coronary flow (= global coronary flow/pressure-rate product). 3. LUT significantly diminished epicardial NADH-fluorescence area and intensity. 4. LUT is an inodilator possessing cardioprotective properties. These might be related to an improvement of myocardial perfusion and/or to free radical scavenging properties.

Simple and rapid high-performance liquid chromatography method for the determination of alcuronium in human plasma and urine.

A simple and quick HPLC assay for alcuronium is presented. Its characteristics are: precipitation of plasma proteins by acetonitrile; Spherisorb 5-CN column; acetonitrile-water (46:54, v/v) as mobile phase; flow-rate 1 ml/min; laudanosine 0.06 mg/l as internal standard with plasma; external standard with urine; UV detection at 294 nm; retention time 5.4 min; detection limit 0.025 mg/l; documented linearity: 0.025-2.0 mg/l for plasma and 1.0-80 mg/l for urine; intra- and inter-assay variability below 4%. None of nine drugs used in perioperative pharmacotherapy interfered with the assay. Satisfactory performance was exemplified in a 12-h pharmacokinetic evaluation of two patients.