Novel Microneedle Patches for Active Insulin Delivery are Efficient in Maintaining Glycaemic Control: An Initial Comparison with Subcutaneous Administration

Purpose Good glycaemic control is essential to minimize the risk for diabetes-induced complications. Also, compliance is likely to be higher if the procedure is simple and painless. This study was designed to validate painless intradermal delivery via a patch-like microneedle array. Materials and Methods Diabetes was induced by an intravenous injection of streptozotocin (50 mg/kg bw) in adult male Sprague Dawley rats. Plasma insulin and blood glucose were measured before, during and after subcutaneous or intradermal (microneedles) infusion of insulin (0.2 IU/h) under Inactin-anaesthesia. Results Before insulin administration, all animals displayed a pronounced hyperglycaemia (19 ± 1 mM; 359 mg/dl). Administration of insulin resulted in a reduced plasma glucose independently of administration route (subcutaneous 7.5 ± 4.2, n = 9, and intradermal 11 ± 1.8, n = 9 after 240 min), but with less errors of the mean in the intradermal group. In the intradermal group, plasma insulin was increased in all latter measurements (72 ± 22, 81 ± 34, and 87 ± 20 μIU/ml), as compared to the first measurement (26 ± 13). In the subcutaneous group, plasma insulin was elevated during the last measurement (to 154 ± 3.5 μIU/ml from 21 ± 18). Conclusion This study presents a novel possibility of insulin delivery that is controllable and requires minimal training. This treatment strategy could improve compliance, and thus be beneficial for patients’ glycaemic control.     

Differential inhibition of hepatic and duodenal sulfation of (−)-salbutamol and minoxidil by mefenamic acid

Objective: The aim of this investigation was to determine whether mefenamic acid and salicylic acid inhibit the sulfation of (−)-salbutamol and minoxidil in the human liver and duodenum, and if so, to ascertain whether the 50% inhibitory concentration (IC₅₀) estimates are different in the two tissues. Methods: Sulfotransferase activities were measured for 10 mM (−)-salbutamol and 5 mM minoxidil, and the concentration of 3′-phosphoadenosine-5′-phosphosulphate-[³⁵S] was 0.4 μM. Results: The IC₅₀ estimates for (−)-salbutamol and minoxidil sulfation of mefenamic acid were 72 ± 5.4 nM and 1.5 ± 0.6 μM (liver), respectively, and 161 ± 23 μM and 420 ± 18 μM (duodenum), respectively. The figures for the liver were significantly lower (P < 0.0001) than those for the duodenum. The IC₅₀ estimates for (−)-salbutamol sulfation of salicylic acid were 93 ± 11 μM (liver) and 705 ± 19 μM (duodenum, P < 0.0001). Salicylic acid was a poor inhibitor of minoxidil sulfation. Conclusion: The IC₅₀ estimates for (−)-salbutamol sulfation of mefenamic acid and salicylic acid are lower than their unbound plasma concentrations after standard dosing, suggesting that mefenamic acid and salicylic acid should inhibit the hepatic sulfation of (−)-salbutamol in vivo. Received: 11 November 1999 / Accepted in revised form: 28 April 2000     

Effects of receptor density on Nociceptin/OrphaninFQ peptide receptor desensitisation: studies using the ecdysone inducible expression system

Pretreatment of the G-protein coupled nociceptin receptor (NOP) with nociceptin/orphaninFQ (N/OFQ) produces desensitisation. The influences of receptor expression and genomic effects are largely unknown. We have used an ecdysone-inducible NOP expression system in a CHO line (CHO_INDhNOP) to examine the effects of N/OFQ pretreatment upon receptor density, GTPγ[³⁵S] binding, cAMP formation and NOP-mRNA. CHO_INDhNOP induced with 5 and 10 μM PonasteroneA (PonA) for 20 h produced NOP densities (B _max) of 194 and 473 fmol. mg^-1 protein, respectively. This was accompanied by decreased NOP mRNA. The lower B _max is typical of the central nervous system. Pretreatment with 1 μM N/OFQ significantly (p < 0.05) reduced B _max at 5 and 10 μM PonA to 100 and 196 fmol. mg^-1 protein, respectively. There was no change in binding affinity. Along with the reduction in B _max, potency and efficacy for N/OFQ-stimulated GTPγ[³⁵S] binding were also reduced (5 μM PonA: pEC₅₀-control = 8.55 ± 0.06, pretreated = 7.88 ± 0.07; E _max-control = 3.52 ± 0.43, pretreated = 2.48 ± 0.10; 10 μM PonA: pEC₅₀-control = 8.41 ± 0.18, pretreated = 7.76 ± 0.03; E _max-control = 5.07 ± 0.17, pretreated = 3.38 ± 0.19). For inhibition of cAMP formation, there was a reduction in potency (5 μM PonA: pEC₅₀-control = 9.78 ± 0.08, pretreated = 8.92 ± 0.13; 10 μM PonA: pEC₅₀-control = 9.99 ± 0.07, pretreated = 9.04 ± 0.14), but there was no reduction in efficacy. In addition, there were 39 and 31% reductions in NOP mRNA at 5 and 10 μM PonA, respectively, but these measurements were made following concurrent N/OFQ challenge and PonA induction. In CHO_INDhNOP, we have shown a reduction in cell surface receptor numbers and a reduction in functional coupling after N/OFQ pretreatment. This was observed at pseudo-physiological and supraphysiological receptor densities. Moreover, we also report a reduction in NOP mRNA, but further studies are needed which include ‘pulsing’ PonA and desensitizing following wash-out.     

The protective effect of HMG-CoA reductase inhibitors against monocrotaline-induced pulmonary hypertension in the rat might not be a class effect: comparison of pravastatin and atorvastatin

Hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, so called statins, improve endothelial function and exert antiproliferative effects on vascular smooth muscle cells of systemic vessels. This study aimed at comparing the protective effects of two statins, pravastatin and atorvastatin, against monocrotaline (MC)-induced pulmonary hypertension in rats. Pravastatin or atorvastatin (PS or AS, 10 mg/kg per day) or vehicle were given orally for 28 days to Wistar male rats injected or not with MC (60 mg/kg intraperitoneally). At 4 weeks, MC-injected rats developed severe pulmonary hypertension, with an increase in right ventricular pressure (RVP) and right ventricle/left ventricle + septum weight ratio associated with a decrease in acetylcholine- or sodium-nitroprusside-induced pulmonary artery dilation observed in vitro. Hypertensive pulmonary arteries exhibited an increase in medial thickness and endothelial cell apoptosis and a decrease of endothelial nitric oxide synthase (eNOS) expression. MC-rat lungs showed a significant decrease of eNOS (P < 0.01) and increase of cleaved caspase-3 (P < 0.05) expression determined by Western blotting. PS (P = 0.02) but not AS (P = 0.30) significantly limited the development of pulmonary hypertension (RVP in mmHg: 30 ± 3, 36 ± 4 vs. 45 ± 4 and 14 ± 1 for MC + PS, MC + AS, MC, and control groups, respectively). Both statins significantly reduced MC-induced right ventricle hypertrophy [RV/left ventricular (LV) + S, in mg/g: 0.46 ± 0.04, 0.39 ± 0.03, 0.62 ± 0.05 and 0.29 ± 0.01 for MC + PS, MC + AS, MC, and control groups, respectively; P < 0.05),and reduced MC-induced thickening (61 ± 6 μm, 82 ± 5 μm, 154 ± 4 μm, and 59 ± 2 μm for MC + PS, MC + AS, MC, and control groups, respectively; P = 0.01) of small intrapulmonary artery medial wall, with MC + AS still being different from the control group. PS but not AS partially restored acetylcholine-induced pulmonary artery vasodilation in MC rats (E_max=65 ± 5%, 49 ± 6%, 46 ± 3%, and 76 ± 4% for MC + PS, MC + AS, MC, and control groups, respectively; P < 0.05 for MC + PS vs. other groups). Both statins prevented apoptosis and restored eNOS expression of pulmonary artery endothelial cells as well as in the whole lung with a more pronounced effect with PS compared with AS. In conclusion, despite its effects on eNOS expression, apoptosis, and medial wall thickening, AS was unable to significantly reduce pulmonary hypertension and to restore endothelium-dependent relaxation, suggesting intermolecular differences between the two HMG-CoA reductase inhibitors in the protection against MC-induced hypertension.     

Pharmacokinetics and distribution of 6-mercaptopurine administered intravenously in children with lymphoblastic leukaemia

Objective: The pharmacokinetics of 6-mercaptopurine, including cerebrospinal-fluid (CSF) distribution, and the erythrocyte 6-thioguanine nucleotide concentrations were determined in children randomised to receive intravenous mercaptopurine for acute lymphoblastic leukaemia (ALL), according to the EORTC protocol ALL n°58881. Results: After 1 month of oral treatment at a dose of 50 mg · m⁻² · day⁻¹, the pharmacokinetic parameters were determined after the first i.v. administration of 1 g · m⁻² (bolus dose of 0.2 g · m⁻² followed by an 8-h infusion of 0.8 g · m⁻²) in 11 patients: systemic clearance was 23.02 l · h⁻¹, volume of distribution was 0.75 l · kg⁻¹, and elimination half-life was 1.64 h. The erythrocyte thioguanine concentrations were measured in the same 11 patients and increased significantly between the beginning and the end of infusion (10 pmol × 10⁸ packed RBC) or within 24 h of infusion (223 pmol × 10⁸ packed RBC). The CSF concentration was 3.78 μmol · l⁻¹, 1–6 h after the beginning of infusion (n=28) and the CSF to plasma ratio was 0.15 (n=16). In patients receiving the oral dose of 50–165 mg · m⁻² · day⁻¹ of 6-mercaptopurine, CSF concentrations were below 0.18 μmol · l⁻¹, 1–24 h after drug intake (n=67), and the CSF to plasma ratio was not calculated. Conclusion: Following the i.v. administration of 6-mercaptopurine, we observed high CSF concentrations of 6-mercaptopurine and an acute increase of erythrocyte thioguanine nucleotide concentrations. The clinical trial (EORTC protocol ALL n°5881), comparing the oral and i.v. administrations of mercaptopurine, will demonstrate if the i.v. administration reduces the incidence of CNS relapses. Received: 15 August 1996 / Accepted in revised form: 8 April 1997     

The effects of acute falciparum malaria on the disposition of caffeine and the comparison of saliva and plasma-derived pharmacokinetic parameters in adult Nigerians

Objectives: The pharmacokinetics of caffeine and its dimethylxanthine metabolites were evaluated in Nigerians, for whom it is normal to consume caffeine-containing beverages during ill health and recuperation in the belief that caffeine aids early recovery from illness; however, there are no data defining the kinetics of caffeine in healthy and ill Nigerians. Materials and methods: A single oral dose of 300 mg caffeine was given to ten healthy adult Nigerians and ten adults suffering from acute uncomplicated Plasmodium falciparum malaria infection. Caffeine and its dimethylxanthine metabolites were measured in plasma and saliva of healthy subjects and in plasma of patients suffering from malaria using high-performance liquid chromatography. Results: The plasma pharmacokinetics of caffeine per se in both groups was similar (P > 0.05). The maximum plasma concentration (C_max) of paraxanthine was significantly lower (P < 0.05) in malaria (0.9 ± 0.4 μg/ml) than in healthy controls (1.4 ± 0.5 μg/m1), and the paraxanthine:caffeine area under the plasma concentration–time curve ratio, an index of cytochrome P₄₅₀ (CYP)IA2 activity was significantly lower (P < 0.05) in malaria patients (0.5 ± 0.1) than in healthy controls (0.3 ± 0.2). The elimination half-life of theophylline was longer in malaria, while the area under the plasma concentration–time curve of theobromine was significantly higher (P < 0.05) in malaria (7.1 ± 3.4 μg ml⁻¹ h) than in healthy adults (4.1 ± 2.2 μg ml⁻¹ h). Excellent correlations were found between saliva and plasma concentrations of caffeine (r ²=0.98) with a mean saliva:plasma concentrations ratio of 0.7 ± 0.1. The plasma concentrations (C_max and AUC) were therefore higher than the corresponding salivary levels, so that the apparent oral clearance calculated for saliva exceeded the true oral clearance based on plasma data. Conclusions: Acute Plasmodium falciparum malaria produced significant changes in the disposition of caffeine metabolites. Analysis of concentrations in saliva is a useful non-invasive method for monitoring the kinetics of caffeine and paraxanthine in Nigerians. Received: 14 April 1999 / Accepted in revised form: 30 November 1999     

Safety of the novel atrial-selective K+-channel blocker AVE0118 in experimental heart failure

Congestive heart failure (CHF) is often associated with atrial fibrillation. The safety of many antiarrhythmic drugs in CHF is limited by proarrhythmic effects. We aimed to assess the safety of a novel atrial-selective K⁺-channel blocker AVE0118 in CHF compared to a selective (dofetilide) and a non-selective IKr blocker (terfenadine). For the induction of CHF, rabbits (n = 12) underwent rapid right ventricular pacing (330–380 bpm for 30 days). AVE0118 (1 mg/kg) dofetilide (0.02 mg/kg) and terfenadine (2 mg/kg) were administered in baseline (BL) and CHF. A six-lead ECG was continuously recorded digitally for 30 min after each drug administration. At BL, dofetilide and terfenadine significantly prolonged QTc interval (218 ± 30 ms vs 155 ± 8 ms, p = 0.001 and 178 ± 23 ms vs. 153 ± 12 ms, p =  0.01, respectively) while QTc intervals were constant after administration of AVE0118 (p = n.s.). In CHF, dofetilide and terfenadine caused torsades de pointes and symptomatic bradycardia, respectively, and prolonged QTc interval (178 ± 30 ms vs. 153 ± 14 ms, p = 0.02 and 157 ± 7 ms vs. 147 ± 10 ms, p = 0.02, respectively) even at reduced dosages, whereas no QTc-prolongation or arrhythmia was observed after full-dose administration of AVE0118. In conclusion, atrial-selective K⁺-channel blockade by AVE0118 appears safe in experimental CHF. H.-J. Schneider and O. Husser contributed equally.     

Kinetics and state-dependent effects of verapamil on cardiac L-type calcium channels

The voltage dependence and the kinetics of block by verapamil of L-type calcium current (I_Ca) were investigated in ventricular myocytes from rat hearts using the whole-cell patch-clamp technique. I_Ca was elicited repetitively in response to depolarizing voltage pulses from –80 mV to 0 mV at different pulse intervals and durations. Verapamil reduced the magnitude of I_Ca in a frequency-dependent manner without tonic component. The time course of I_Ca remained unchanged suggesting that not open but inactivated channels were affected by the drug. The interaction of verapamil with inactivated channels was investigated by the application of twin pulses. In the presence of verapamil, the duration of the first pulse significantly determined the magnitude of I_Ca during the second pulse. Variation of the duration of the first pulse between 12 and 3000 ms, followed by a pulse interval of 100 ms, resulted into a gradual decrease of I_Ca during the second pulse (180 ms), described by concentration-dependent monoexponential decay curves (t = 1060 ± 138 ms at 0.3 μM (n = 3); t = 310 ± 24 ms at 1 μM (n = 6), and t = 125 ± 7 ms at 10 μM (n = 5); means ± SEM). Under control conditions, the changes in I_Ca were comparably negligible. The recovery of I_Ca from block was analyzed by the application of a twin pulse protocol in which two depolarising voltage pulses at fixed length (1. pulse at 3 s and 2. pulse at 180 ms) were interrupted by variable pulse intervals (6 ms–60 s). Under control conditions, recovery from inactivation was fast (t = 11 ± 0.7 ms; means ± SEM; n = 3). In the presence of verapamil, recovery from block was about 500times slower than under control conditions, independent of the drug concentration (t = 5.05 ± 0.44 s at 0.3 μM (n = 3), t = 6.7 ± 0.69 s at 1 μM (n = 4), and t = 6.02 ± 0.9 s at 10 μM (n = 5); means ± SEM). Since development of block was dependent on the concentration of verapamil, whereas recovery from block was independent from the drug concentration, it is assumed that the described time constants for block and unblock reflect voltage-dependent net binding (τ_on) and unbinding (τ_off), respectively, of verapamil at its receptor sites. A computer simulation, including the time constants of block development at 0 mV and of recovery from block at –80 mV, predicted reasonably well the observed frequency-dependent block of I_Ca by verapamil. The development of either measured or calculated block of I_Ca, using 180 ms depolarising voltage pulses from –80 mV to 0 mV, was fitted by identical monoexponential association curves (t = 7 s each at 0.2 Hz and t = 1.7 s each at 1 Hz). When Ba²⁺ was used as the charge carrier, which removes the calcium-dependent inactivation of the current, verapamil (3 μM) was less efficient: I_Ca was decreased by 57 ± 6 % (means ± SEM; n = 6), whereas I_Ba was decreased by 24 ± 4 % (means ± SEM; n = 5). It is proposed that verapamil binds to calcium channels in their inactivated state at more positive potentials and dissociates from the channels in the resting state at more negative potentials. In the proposed scheme of periodical drug binding and unbinding, dependent on the state of the channels, the development of frequency-dependent block of I_Ca by verapamil is adequately predicted by the construction of cumulative association/dissociation curves which include the experimentally determined time constants of development and recovery from block at 0 mV and –80 mV, respectively. Received: 17 May 1996 / Accepted: 23 September 1996     

Oral bambuterol compared to inhaled salmeterol in patients with partially reversible chronic obstructive pulmonary disease

Objective: There is now good evidence that inhaled salmeterol is an effective agent in chronic obstructive pulmonary disease (COPD),but, at the present time, data on the effects of bambuterol, which is an oral tarbutaline pro-drug, in patients with COPD are scarce. Moreover, no comparative study between bambuterol and salmeterol in patients with chronic obstructive airway disorders has been published. The objective of this research was, consequently, to compare the efficacy and safety of 20 mg oral bambuterol and 50 μg inhaled salmeterol in patients with partially reversible COPD. Methods: The speed and length of bronchodilation with 20 mg bambuterol and 50 μg inhaled salmeterol were compared in 16 patients with partially reversible COPD. The investigation and designed as a double-blind, double-dummy, cross-over, placebo controlled and randomised study. Lung function (FEV₁, FVC) and systemic variables (subjective tremor, heart rate, blood pressure) were monitored prior to the administration of the drug and for 12 h after each agent on 3 non-consecutive days. Results: Inhalation of salmeterol induced a significant (P < 0.05) increase of lung function when compared with placebo. In addition, oral bambuterol elicited good bronchodilation, with its maximum slightly later than for salmeterol. The mean (±SE) AUC_0–12 hs for all patients were 3.134 1 ± 0.553 for salmeterol and 1963 1 ± 0.573 for bambuterol. Both AUC_0–12 h s were significantly greater than for placebo (P < 0.05), but there was no significant difference (P = 0.077) between the salmeterol and bambuterol AUC_0–12 hs. Bambuterol, but not salmeterol, caused tremor in four patients. Moreover, it induced a higher heart rate when compared with salmeterol at each considered time after the administration of the drug; differences after 9 and 12 h  were statistically significant (P < 0.05). Conclusion: Both oral bambuterol and inhaled salmeterol resulted in good bronchodilation in patients with stable COPD. However, bambuterol, but not salmeterol, caused tremor in several subjects and elicited a more pronounced tachycardia. Received: 11 May 1998 / Accepted in revised form: 13 September 1998     

Inhibition of metoprolol metabolism and potentiation of its effects by paroxetine in routinely treated patients with acute myocardial infarction (AMI)

Objective To investigate the influence of paroxetine on metoprolol concentrations and its effect in patients treated for acute myocardial infarction (AMI) who are routinely given paroxetine as a co-treatment of depression. Methods We recruited 17 depressed AMI patients who received metoprolol as a routine part of their therapy (mean dose 75 ± 39 mg/day). Patients were genotyped for CYP2D6 *3, *4 and gene duplication. Metoprolol and α-hydroxy-metoprolol were analyzed in plasma 0, 2, 6 and 12 h post-dose. Heart rates (HR) at rest were registered after each sampling. Paroxetine 20 mg daily was then administered, and all measurements were repeated on day 8. Results All patients were genotypically extensive metabolizers (EMs) (nine with *1/*1 and eight with *1/*3 or *4). Following the administration of paroxetine, mean metoprolol areas under the concentration–time curve (AUC) increased (1064 ± 1213 to 4476 ± 2821 nM × h/mg per kg, P = 0.0001), while metabolite AUCs decreased (1492 ± 872 to 348 ± 279 n M × h/mg per kg, P < 0.0001), with an increase of metabolic ratios (MR) (0.9 ± 1.3 to 26 ± 29; P < 0.0001). Mean HRs were significantly lower after the study week at each time point. Mean area under the HR versus time curve (AUEC) decreased (835 ± 88 to 728 ± 84 beats × h/min; P = 0.0007). Metoprolol AUCs correlated with patients’ AUECs at the baseline (Spearman r  = −0.64, P < 0.01), but not on the eighth day of the study. A reduction of metoprolol dose was required in two patients due to excessive bradycardia and severe orthostatic hypotension. No other adverse effects of the drugs were identified. Conclusion A pronounced inhibition of metoprolol metabolism by paroxetine was observed in AMI patients, but without serious adverse effects. We suggest, however, that the metoprolol dose is controlled upon initiation and withdrawal of paroxetine.     

Serum and urinary boron levels in rats after single administration of sodium tetraborate

The pharmacokinetics of boron was studied in rats by administering a 1 ml oral dose of sodium tetraborate solution to several groups of rats (n=20) at eleven different dose levels ranging from 0 to 0.4 mg/100 g body weight as boron. Twenty-four-hour urine samples were collected after boron administration. After 24 h the average urinary recovery rate for this element was 99.6 ± 7.9. The relationship between boron dose and excretion was linear (r=0.999) with a regression coefficient of 0.954. This result suggests that the oral bioavailability (F) of boron was complete. Another group of rats (n=10) was given a single oral injection of 2 ml of sodium tetraborate solution containing 0.4 mg of boron/100 g body wt. The serum decay of boron was followed and found to be monophasic. The data were interpreted according to a one-compartment open model. The appropriate pharmacokinetic parameters were estimated as follows: absorption half-life, t _1/2a=0.608±0.432 h; elimination half-life, t _1/2=4.64±1.19 h; volume of distribution, Vd=142.0±30.2 ml/100 g body wt.; total clearance, C _tot=0.359 ± 0.0285 ml/min per 100 g body wt. The maximum boron concentration in serum after administration (C _max) was 2.13 ± 0.270 mg/l, and the time needed to reach this maximum concentration (T _max) was 1.76 ± 0.887 h. Our results suggest that orally administered boric acid is rapidly and completely absorbed from the gastrointestinal tract into the blood stream. Boric acid in the intravascular space does not have a strong affinity to serum proteins, and rapidly diffuses to the extravascular space in proportion to blood flow without massive accumulation or binding in tissues. The main route of boron excretion from the body is via glomerular filtration. It may be inferred that there is partial tubular resorption at low plasma levels. The animal model is proposed as a useful tool to approach the problem of environmental or industrial exposure to boron or in cases of accidental acute boron intoxication. Received: 1 December 1997 / Accepted: 24 March 1998     

The effect of folic acid supplementation on the pharmacokinetics and pharmacodynamics of oral methotrexate during the remission-induction period of treatment for moderate-to-severe plaque psoriasis

Objective We assessed the effect of folic acid (FA) on the pharmacokinetics and pharmacodynamics of low-dose oral methotrexate (MTX) during the remission-induction phase of psoriasis treatment. Methods In a 32-week, open-label, two-way cross-over study, patients (n = 20, seven men, aged 35–70 years) with moderate-to-severe plaque psoriasis were randomly assigned to receive MTX plus FA (20 mg/week) for 16 weeks followed by MTX monotherapy (three doses of MTX separated by 12-h intervals once a week) for an additional 16 weeks (treatment arm A, n = 10) or to receive the opposite sequence of treatments (arm B, n = 10). Dosing of MTX was individualised with the help of pre-study evaluation of plasma MTX pharmacokinetics. The Psoriasis Area and Severity Index (PASI), biochemistry and haematology tests and erythrocyte concentration of MTX polyglutamates (MTXPG) were evaluated throughout the study. Results In arms A and B, the mean (range) concentrations of MTXPG (nmol/L) were comparable [week 16: 96.2 (32.0–157) vs. 111 (73.7–175), P = 0.32; week 32: 103 (55.8–173) vs. 83.6 (27.4–129), P = 0.24]. After 16 weeks, the mean±SEM PASI decreased from 20.1 ± 2.1 to 8.8 ± 1.3 in arm A, while a greater reduction from 27.2 ± 2.1 to 5.1 ± 1.0 occurred in arm B (P < 0.001). Positive correlations were found between the percent improvement in PASI at week 16 and the ratios of the concentration of MTXPG to plasma folate (rho = 0.59, P = 0.008) or RBC folate concentration (rho = 0.56, P = 0.013). Due to an accelerated decline in PASI in arm A and a trend to its worsening in arm B after crossing over of treatments, the mean absolute PASI scores in both arms were comparable at week 32. Conclusion The antipsoriatic effect of MTX during the remission-induction phase of treatment is influenced by folate status and may be significantly less if combined treatment with FA is used, irrespective of pre-treatment folate levels. The individual tailoring of MTX dosing needs further attention because the mean percent PASI improvement from baseline was 83% and the inter-patient variability in response was low after 16 weeks of monotherapy with MTX.     

Pharmacokinetics of intravenous ATP in cancer patients

Objective: To characterise the pharmacokinetics of adenosine 5′-triphosphate (ATP) in patients with lung cancer after i.v. administration of different ATP dosages. Methods: Twenty-eight patients received a total of 176 i.v. ATP courses of 30 h. Fifty-two infusions were given as low-dose infusions of 25–40 μg kg⁻¹ min⁻¹, 47 as middle-dose infusions of 45–60 μg kg⁻¹ min⁻¹ and 77 as high-dose infusions of 65–75 μg kg⁻¹ min⁻¹ ATP. Kinetic data of ATP concentrations in erythrocytes were available from 124 ATP courses. Results are expressed as mean ± SEM. Results: Most ATP courses in cancer patients were without side effects (64%), and side effects occurring in the remaining courses were mild and transient, resolving within minutes after decreasing the infusion rate. Baseline ATP concentration in erythrocytes was 1554 ± 51 μmol l⁻¹. ATP plateau levels at 24 h were significantly increased by 53 ± 3, 56 ± 3 and 69 ± 2% after low-dose, middle-dose and high-dose ATP infusions, respectively. At the same time, significant increases in plasma uric acid concentrations were observed: 0.06 ± 0.01, 0.11 ± 0.01 and 0.16 ± 0.01 mmol l⁻¹, respectively. The mean half-time for disappearance of ATP from erythrocytes, measured in five patients, was 5.9 ± 0.5 h. Conclusions: During constant i.v. infusion of ATP in lung cancer patients, ATP is taken up by erythrocytes and reaches dose-dependent plateau levels 50–70% above basal concentrations at approximately 24 h. Received: 7 July 1999 / Accepted in revised form: 30 December 1999     

Absorption of effervescent paracetamol tablets relative to ordinary paracetamol tablets in healthy volunteers

Objectives: The aim of this study was to compare the rate of absorption between ordinary paracetamol tablets and effervescent paracetamol tablets. Methods: Twenty healthy volunteers participated in an open randomised crossover study and were given a 1000-mg dose of either ordinary paracetamol tablets (2 × 500 mg Panodil tablets, SmithKline Beecham) or effervescent paracetamol tablets (2 × 500 mg Pinex Brusetablett, Alpharma AS) with a 3-week washout period in between. Blood samples were collected for 3 h. Maximum serum concentration (C_max) and the time to maximum serum concentration (t_max) were recorded and the area under the concentration versus time curve (AUC) was calculated. Results: The mean t_max was significantly shorter when paracetamol effervescent tablets were taken (27 min) rather than ordinary paracetamol tablets (45 min) (P=0.004). There was no significant difference between the mean C_max of 143 μmol/l with effervescent tablets and that of 131 μmol/l with ordinary tablets. The mean AUC_0–3 h was significantly higher with paracetamol effervescent tablets (223.8 μmol · h · l⁻¹) than with ordinary tablets (198.2 μmol · h · l⁻¹; P=0.003). After 15 min, 17 (85%) subjects in the effervescent group had a serum concentration of 70 μmol/l (lower therapeutic serum concentration) or higher relative to only 2 (10%) subjects in the ordinary tablet group (P=0.001). Conclusion: Paracetamol effervescent tablets are absorbed significantly faster than ordinary paracetamol. Thus, effervescent tablets might offer significantly faster pain relief when paracetamol is used. Received: 4 October 1999 ;/ Accepted in revised form: 15 February 2000     

Measurement of furancarboxylic acid, a candidate for uremic toxin, in human serum, hair, and sweat, and analysis of pharmacological actions in vitro

3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), a candidate for uremic toxin, was measured in human hair for examining a possible utility as indicator of renal dysfunction. The serum concentration of CMPF was much higher (32.3 ± 2.7 μg/ml, n=17; mean ± SEM) in uremic patients aged 40–55 years receiving hemodialysis treatment than in healthy younger subjects (3.61 ± 0.19 μg/ml, n=22), aged 18–23 years. However, the hair concentration of CMPF tended to be lower in the patients (6.8 ± 1.7 ng/10 mg hair) than in the healthy younger subjects (15.8 ± 4.5 ng/10 mg) and was significantly lower than that in the healthy age-matched subjects (22.4 ± 5.3 ng/10 mg, n=12), aged 40–47 years. Since CMPF was measurable in the sweat (4.4 ± 3.7 ng/mg) collected from six out of seven healthy subjects examined, it was suggested that the contribution of sweat to the measurement of CMPF in hair was considerable. The fact that the uremic patients undergoing hemodialysis therapy had less sweat than healthy subjects may explain the lower concentration of CMPF in the patients' hair. The pathophysiological roles of CMPF in the body were attempted to be explored by using excised guinea pig organs, and human platelets and neutrophils. CMPF showed no remarkable effects in the concentration range of ≤10⁻⁴ M except for only slight suppression of spontaneous contracture of guinea pig tenia coli at 10⁻⁴ M. As far as the organs and tissues examined in the present study are concerned, the biological activity of CMPF itself, if any, may be very weak. Precaution should be taken against the delivery of a substance through sweat to hair when a small amount of substance is attempted to be measured in hair by employing a sensitive analytical method. Received: 14 September 1999 / Accepted: 3 November 1999     

Activity of O6-methylguanine DNA methyltransferase in mononuclear blood cells of formaldehyde-exposed medical students

A recent study reported that exposure of student embalmers in Cincinnati to high concentrations of formaldehyde (2 mg/m³) reduced the activity of the DNA repair protein O⁶-methylguanine DNA methyltransferase (MGMT). Reduction in a DNA repair enzyme may strongly increase the cancer risk not only with respect to the repair-enzyme causing agent but with respect to all carcinogens causing lesions subject to repair by the enzyme in question. Thus, we examined whether formaldehyde exposure of 57 medical students during their anatomy course at two different Universities in Germany influenced MGMT activity in mononuclear blood cells. Mean formaldehyde exposure of 41 students was 0.2 ± 0.05 mg/m³ for 6 h per week. MGMT activity was 133.2 ± 14.9 fmol MGMT/10⁶ cells before the beginning of the formaldehyde exposure, 131.1 ± 15.8 fmol MGMT/10⁶ cells after 50 days (P = 0.56) and 128.2 ± 19.0 fmol MGMT/10⁶ cells after 111 days of exposure (P=0.92). Similarly, no significant influence of formaldehyde exposure was observed, when smoking habits, alcohol consumption, allergic disease and sex of students were considered. In addition no significant difference was obtained in MGMT activity between 16 students with mean formaldehyde exposure of 0.8 ± 0.6 mg/m³ and students without formaldehyde exposure (n=51; P=0.37). In conclusion, exposure of the medical students in western Europe to formaldehyde did not decrease MGMT activity in mononuclear blood cells. Received: 22 September 1998 / Accepted: 4 November 1998     

Evaluation of the dose-response relationship for intra-nasal oxymetazoline hydrochloride in normal adults

Objectives: To evaluate the dose-response relationship of increasing doses of oxymetazoline compared with placebo in normal subjects, and to determine the sensitivities of rhinomanometry, acoustic rhinometry and symptoms in discriminating between differing doses of oxymetazoline in normal subjects. Methods: The study had a randomized, double-blind, placebo-controlled, parallel group, dose-response design. One hundred and twenty-five healthy volunteers with no nasal obstruction were randomized to administration of a single intra-nasal dose of oxymetazoline (6.25 μg, 12.5 μg, 25 μg or 50 μg) or placebo to each nasal cavity. Nasal airway resistance (NAR) was measured by active posterior rhinomanometry. Total minimum cross-sectional area (tMCA) and volume (tVOL) were measured by acoustic rhinometry. Symptoms of congestion (CON) were assessed on a visual analogue scale. Results: The two highest doses of oxymetazoline produced a significant decrease in NAR compared with placebo (P = 0.015) but not between placebo and 12.5 μg or 6.25 μg. There was a dose-response relationship for tVOL, which increased significantly after all doses compared with placebo (P < 0.001) and showed differences between 6.25-μg and 25-μg (P < 0.014) and 12.5-μg and 50-μg (P < 0.05) doses. tMCA increased compared with placebo after all treatments (P = 0.028), but there were no significant differences between any of the active doses. There were no significant changes in CON after any treatments compared with placebo. Conclusions: tVOL shows a clear dose-response relationship for the range of doses of oxymetazoline administered. tVOL provides a sensitive and discriminatory measure of small nasal changes after low doses of oxymetazoline. NAR is able to discriminate between doses, but is less sensitive than tVOL and tMCA, requiring a higher threshold dose before significant changes are seen in nasal patency. Received: 1 March 1999 / Accepted in revised form: 17 May 1999     

The plasma and cerebrospinal fluid pharmacokinetics of sorafenib after intravenous administration in non-human primates

Purpose Sorafenib is a small molecule inhibitor of multiple signaling kinases thought to contribute to the pathogenesis of many tumors including brain tumors. Clinical trials with sorafenib in primary and metastatic brain tumors are ongoing. We evaluated the plasma and cerebrospinal fluid (CSF) pharmacokinetics (PK) of sorafenib after an intravenous (IV) dose in a non-human primate (NHP) model. Methods 7.3 mg/kg of sorafenib free base equivalent solubilized in 20% cyclodextrin was administered IV over 1 h to three adult rhesus monkeys. Serial paired plasma and CSF samples were collected over 24 h. Sorafenib was quantified with a validated HPLC/tandem mass spectrometry assay. PK parameters were estimated using non-compartmental methods. CSF penetration was calculated from the AUC_CSF : AUC_plasma. Results Peak plasma concentrations after IV dosing ranged from 3.4 to 7.6 μg/mL. The mean ± standard deviation (SD) area under the plasma concentration from 0 to 24 h was 28 ± 4.3 μg•h/mL, which is comparable to the exposure observed in humans at recommended doses. The mean ± SD clearance was 1.7 ± 0.5 mL/min/kg. The peak CSF concentrations ranged from 0.00045 to 0.00058 μg/mL. The mean ± SD area under the CSF concentration from 0 to 24h was 0.0048 ± 0.0016 μg•h/mL. The mean CSF penetration of sorafenib was 0.02% and 3.4% after correcting for plasma protein binding. Conclusion Sorafenib is well tolerated in NHP and measurable in CSF after an IV dose. The CSF penetration of sorafenib is limited relative to total and free drug exposure in plasma.     

Acute hormonal changes after IV citalopram and treatment response in OCD

Rationale Serotonergic pharmacological challenges have failed to produce consensual results in patients with obsessive–compulsive disorder (OCD), suggesting a heterogeneous 5-hydroxytryptamine (5-HT) activity in this disorder. Objectives The aim of this study was to compare the neuroendocrine response to a serotonergic challenge in OCD patient responders (RP) and nonresponders (NR) to serotonin reuptake inhibitors treatment and healthy volunteers. Materials and methods Thirty OCD treatment NR, 30 RP, and 30 controls (CN) matched for sex and age were included. Each subject received 20 mg of intravenous citalopram. Prolactin, cortisol, and growth hormone plasma concentration were measured at times—20, 0, 20, 40, 60, 80, 100, 120, 140, and 160 min after the onset of citalopram infusion. Results Citalopram did not induce anxiety or OCD symptoms in patients. Citalopram was associated with stronger prolactin response in the CN group (maximal percentage variation [max%Δ] = 65.76 ± 105.1) than in NR (max%Δ = 17.41 ± 31.06) and RP groups (max%Δ = 15.87 ± 31.71; p = 0.032; Friedman χ ² = 6.87; df = 2). On the other hand, cortisol response did not differ between CN and RP groups and was blunted in the NR group (NR max%Δ = 20.98 ± 58.14 vs RP max%Δ = 47.69 ± 66.94; CN max%Δ = 63.58 ± 88.4; p = 0.015; Friedman χ ² = 8.60; df = 2). Conclusions Compared to CN, both treatment RP and NR patients showed blunted prolactin response to citalopram, but only NR patients showed an attenuated cortisol response, suggesting a more disrupted central serotonergic transmission in this group.     

The effects of two systemic α<Subscript>1</Subscript>-adrenergic blockers on pupil diameter: a prospective randomized single-blind study

Our aim was to investigate the effects of two α₁-adrenergic blockers—tamsulosin and alfuzosin—on pupil diameter (PD). In this prospective randomized single-blind clinical trial, 64 patients with benign prostatic hyperplasia received treatment with either tamsulosin or alfuzosin. The same ophthalmologist, masked to the given medication, evaluated patients prior to, 4 weeks after and 6 months after the start of the medication (day 0, day 28 and month 6). Best corrected visual acuity and PD under mesopic, scotopic, and dilated conditions were measured. t-test, ANOVA, and Dunnett’s multiple comparison post-test were used for statistical analysis. With tamsulosin treatment, both mesopic and scotopic PD decreased, respectively, from 3.9 ± 0.7 and 5.7 ± 0.6 mm at day 0 to 3.6 ± 0.9 and 5.5 ± 0.8 mm at day 28, and 3.6 ± 0.7 and 5.4 ± 0.7 mm at month 6 (ANOVA; P = 0.021 and  = 0.040, respectively). However, the difference in dilated PD was not significant (day 0 7.8 ± 0.6 mm, day 28 7.7 ± 0.7 mm, and month 6 7.6 ± 0.6 mm, P = 0.379). In the alfuzosin group, PD did not differ significantly from the baseline except for the scotopic measurements, which decreased from 5.6 ± 0.6 mm at day 0 to 5.5 ± 0.6 mm at day 28 and 5.2 ± 0.8 mm at month 6 (P = 0.004). Compared to baseline values, small but statistically significant decreases were detected in mesopic and scotopic illumination in patients treated with tamsulosin and in scotopic PD in patients treated with alfuzosin. The clinical significance of these differences needs further evaluation.