Effect of surfactant on the size and stability of PLGA nanoparticles encapsulating a protein kinase C inhibitor.

Nowadays many drugs with improved therapeutic efficacy are discovered but cannot be utilized due to their low solubility and insufficient bioavailability. An example of such a drug molecule is a protein kinase C inhibitor that influences an enzyme which plays an important role in several signal transduction cascades. The aim of this study was to formulate a stable nanoparticle dispersion of the PKC inhibitor encapsulated into PLGA nanoparticles (NPs). Encapsulation of the PKC inhibitor into PLGA NPs of 100-200 nm diameter should provide a targeted delivery to the inflammation sites. The NPs were prepared via nanoprecipitation and different surfactants were investigated: Fully and partially hydrolyzed poly(vinyl alcohol) (PVA, Mowiol X-88 and X-98), poloxamers (Pluronic F68 and F127) and polysorbates (Tween 20 and 80). From all surfactants tested, only NPs prepared with partially hydrolyzed PVA (Mowiol X-88) provided the desired stability throughout the downstream processes. These NPs were subsequently analyzed regarding their particle size, polydispersity, encapsulation efficiency and loading capacity. Dynamic light scattering results revealed that monodisperse NPs of 150-220 nm were formed, a size range that favors targeted delivery. The drug encapsulation efficiency varied from 31 to 75% with a drug loading of 1.3-2%. Moreover, the long-term stability was studied and the residual amount of PVA of the NP solutions was quantified via nuclear magnetic resonance (NMR) measurements. The shell-less hen's egg model was used to test toxic effects (hemorrhage, vascular lysis, thrombosis, hemolysis and lethality) of the NPs in a more complex biological system under dynamic flow conditions.

Three cases of renal relapse after allogeneic hematopoietic stem cell transplantation for childhood acute lymphoblastic leukemia.

Isolated renal relapse after allogeneic hematopoietic stem cell transplantation (alloHSCT) in children with acute lymphoblastic leukemia (ALL) is a rare condition. Generally, in ALL, the sites most frequently affected by extramedullary relapse are the central nervous system (CNS) and the testicles. Here we report on three young boys with relapsed B-precursor ALL, who underwent alloHSCT from HLA-identical siblings and suffered a histopathologically proven isolated unilateral renal relapse (two patients) or a combined renal and testicular relapse (one patient) 6, 10 and 12 months post alloHSCT. In all patients at the time of relapse bone marrow showed complete remission with complete donor hematopoiesis. They all received total body irradiation with partial shielding of the kidneys as part of their conditioning therapy, such that renal shielding could be an explanation for the observed accumulation of renal relapses. Moreover, during the past few years so called immune privilege has been postulated for frequent relapse sites such as the CNS, the testicles and the anterior chamber of the eye. Impaired accessability of these organs by cytotoxic T-cells (CTLs) with a reduced graft-versus-leukemia (GvL) effect after alloHSCT is based on a number of different molecular and cellular mechanisms. Similar mechanisms have been shown to be effective in the tubulointerstitial space of the kidney, rendering the kidney a potentially immune privileged site. Due to these observations we advocate sufficient treatment of the kidneys during conditioning therapy.

Drug metabolism in drug-induced liver diseases: pathogenetic role of active metabolites.

Three cases with drug-induced liver diseases (hepatitis caused by hydralasine, steatosis caused by methimazole, choletasis caused by birth control pill) were investigated with respect to their drug metabolising ability. Clinical diagnoses were based on the exclusion of other pathogenetic factors, on histological findings of liver biopsy specimens and on the clinical chemical tests. Investigation of biotransforming ability was carried out using test materials (menthol loading, antipyrine, sulfadimidine, caffeine, indocyanine green kinetics) and measurement of D-glucaric acid excretion. In all cases the results show a defective capacity in some respect of drug metabolism. Possible pathogenetic role of reactive metabolites is discussed in the pathomechanism of genesis of drug-induced liver diseases.

Pharmacokinetics and pharmacodynamics of high dose furosemide in patients with chronic renal failure or nephrotic syndrome.

The pharmacokinetics and pharmacodynamics of repeated oral administration of furosemide were studied in patients with chronic renal failure or nephrotic syndrome using three different dosage regimens (4 x 40, 4 x 80 and 4 x 250 mg/d). Concentrations of the unchanged drug in serum and urine were measured fluorometrically. The elimination kinetics of furosemide was linear over the dose range studied. In contrast, the bioavailability of this diuretic decreased with increasing doses. The diuretic effects of all three dosage regimens were distinct only on the first day of therapy, thereafter decreasing rapidly. It can be concluded that the hormonal regulation of water and electrolyte balance are responsible for this behavior rather than pharmacokinetics. Creatinine and urea nitrogen excretion were not influenced by any furosemide dosage regimen.

[The relative bioavailability of co-trimoxazole suspensions]. / Zur relativen Bioverfügbarkeit von Cotrimoxazol-Suspensionen.

The relative bioavailability of a co-trimoxazole suspension manufactured by VEB Berlin-Chemie (B); Belocid-Suspension was compared with a widespread used suspension (V) in healthy male students (22-29 ys. aged). A single oral dose of 160 mg trimethoprim (TPM) and 800 mg sulphamethoxazole (SMZ) produced similar blood levels with either preparation. The TMP peak levels were 1.44 +/- 0.18 (B) and 1.40 +/- 0.26 mg/l (V), respectively after 1.5 and 1.0 h on an average. The AUC amounted to 18.94 +/- 2.25 (B) and 17.19 +/- 3.62 mg . h/l (V), respectively. About one half (52.5%) of the given TMP dose was excreted unchanged by kidney within 48 h after administration of the respective suspension. The SMZ peak levels run to 37.2 +/- 10.3 (B) and 38.6 +/- 5.4 mg/l (V) after 3.6 +/- 3.5 and 1.3 +/- 0.8 h. The AUC were identical: 682.3 +/- 126.2 (B) vs. 686.9 +/- 165.8 mg . h/l (V). After both preparations 67% of the given SMZ dose could be detected in urine within 48 h. In two out of the eight volunteers the absorption of B was delayed, but it passed off to the same extent. In all other cases absorption of the suspension was accelerated in comparison with tablet administration studies reported. Peak blood levels of TMP and SMZ after ingestion of the suspensions reach the lower range of values resulting from tablet intake. Both suspensions are regarded interchangeable with respect to bioavailability, which is also comparable to co-trimoxazole tablets.

[The effect of intrahepatic cholestasis in pregnancy on various forms of cytochrome P-450-dependent biotransformation reactions]. / Der Einfluss der intrahepatischen Schwangerschaftscholestase auf verschiedene Cytochrom P-450-abhängige Biotransformations-reaktionen.

The elimination of caffeine from plasma and the excretion of the main metabolites of metamizol (noramidopyrinemethanesulphonate sodium) into the urine were determined in healthy pregnant women (weeks 30-38 of pregnancy) and in patients with intrahepatic cholestasis in pregnancy (weeks 28-39 of pregnancy). From the elimination velocity of these model substances conclusions concerning the activity of 3-methylcholanthrene (caffeine elimination) and phenobarbital inducible isoenzymes (metamizol elimination) of cytochrome P-450 are drawn. Patients with intrahepatic cholestasis in pregnancy (t1/2 = 15.8 +/- 1.8 h) eliminate caffeine more slowly than healthy pregnant women (t1/2 = 11.0 +/- 0.8 h) at this stage of pregnancy. The excretion of the metabolites of metamizol is only in tendency diminished in patients with intrahepatic cholestasis. The influence of the intrahepatic cholestasis on the cytochrome P-450 isoenzymes investigated differs in degree.

[Effect of various liver diseases on the activity of 2 subtypes of cytochrome P-450]. / Zum Einfluss von verschiedenen Lebererkrankungen auf die Aktivität zweier Subtypen des Cytochrom P-450.

The elimination of caffeine from the plasma and the elimination of metamizol-metabolites in urine were determined in 37 patients with different liver diseases. In severe liver diseases the demethylation of caffeine as well as the metabolism of metamizol is significantly reduced. The extent of reduced elimination capacity depends on the severity of the disease rather than on the type of disease. In patients with liver cirrhosis the determination of synthesis capacity and of humoral activity (s. tab. I) is suitable to evaluate the capacity of the cytochrome P-450 system. In noncirrhotic diseases only the activity of liver disease (tab. I.) determines the extent of reduced biotransformation capacity. Beside biotransformation-phase I, the acetylation--phase II biotransformation--also appears to be reduced.

The influence of phenobarbital on the pharmacokinetics of propranolol in pregnancy.

In 7 pregnant hypertensive patients the elimination half-life of propranolol was enhanced to 6.1 +/- 1.2 h in comparison to 4.4 +/- 0.4 in 9 nonpregnant females. In 8 out of 11 pregnant hypertensive patients in the 29th week of gestation treated with 90 mg phenobarbital daily for at least 7 days before starting propranolol therapy, the half-life of propranolol was 3.1 +/- 0.4 h only. This significant difference between pregnant women with and without phenobarbital pretreatment is discussed as enzyme induction by phenobarbital.

Beta-adrenoceptor blocking drugs and cytochrome P-450: the influence of propranolol treatment on caffeine, antipyrine, D-glucaric acid and indocyanine green elimination in patients with hepatic disorders.

The effect of the beta-adrenoceptor blocking drug propranolol was investigated in patients with alcoholic liver disease and in those without liver disease before and after ten days treatment with 80 mg daily. Caffeine as a marker drug for the 3-methylcholanthrene-inducible subtype had a significantly enhanced clearance after propranolol in liver-diseased patients, while the clearance of antipyrine which represents the phenobarbital-inducible subtype was unchanged. D-glucaric acid excretion as an endogenous compound which serves as an indicator of induced state of drug-metabolizing capacity of the liver was slightly enhanced in liver patients, but significantly decreased in patients without liver disorders. Indocyanine green elimination as a test material for substances limiting liver blood flow was not significantly reduced by this propranolol dosage.

[Elimination of caffeine and metamizol in in vivo characterization of cytochrome P-450 dependent biotransformation reactions in aged humans]. / Die Elimination von Coffein und Metamizol zur in-vivo-Charakterisierung Cytochrom P-450-abhängiger Biotransformationsreaktionen beim alten Menschen.

Elimination of caffeine from plasma and excretion of main metabolites of metamizol (noramidopyrine methanesulphonate sodium) in urine were determined in young healthy (age 18-27 years) and in old aged volunteers (older than 65 years). From the elimination velocity of these model substances conclusions concerning the activity of 3-methylcholanthrene inducible (caffeine elimination) and of phenobarbital inducible (metamizol elimination) isoenzymes of cytochrome P-450 are drawn. Whereas in old age caffeine metabolism is unchanged, there is a strong delay in renal excretion of main metabolites of metamizol in old volunteers. It is concluded that different hepatic cytochrome P-450 isoenzymes are differentially influenced with increasing age in men.

[The influence of chronic renal insufficiency on the demethylating activities of various cytochrome P-450 subspecies in humans]. / Einfluss der chronischen Niereninsuffizienz auf durch verschiedene Cytochrom P-450-Subspezies katalysierte Demethylierungsaktivitäten beim Menschen.

Caffeine is mainly metabolized by 3-methylcholanthrene-inducible cytochrome P-450 (P-450MC) and metamizol (noramidopyrine methanesulfonate sodium) is mainly metabolized by phenobarbital-inducible cytochrome P-450 (P-450PB). That's why the half life of caffeine and the elimination of the main metabolites of metamizol were used as parameters in vivo characterizing both groups of the cytochrome P-450-complex. The influence of chronic renal insufficiency was investigated (8 patients in the stage of compensated retention, creatinine in serum 380-1280 mumol X l-1, and 6 hemodialyzed patients, here only metamizol elimination was established). Both the caffeine and the metamizol eliminations of patients with chronic renal insufficiency are not different from those of healthy volunteers. We concluded that the demethylation activity of the cytochrome P-450-complex is not distinctly influenced by chronic renal insufficiency.

[Experiences with propranolol (Obsidan25) in hypertension therapy in pregnancy]. / Erfahrungen mit Propranolol (Obsidan25) in der Hochdrucktherapie bei Schwangeren.

The treatment of the mentioned forms of hypertension with propranolol during pregnancy either as monotherapy or in combination with dihydralazine and after careful exclusion of the contraindications described represents a further effective therapy. In the control examinations during pregnancy carried out in close cooperation between obstetrician and internist no detrimental side effects could be established for both mother and child. No significant changes of absorption, distribution and elimination of propranolol in pregnant women with hypertension in comparison with normotensive nonpregnant women were found as follows from the pharmacokinetic parameters shown.

[The pharmacokinetics of cephalothin following single and repeated administration in man]. / Zur Pharmakokinetik von Cefalotin nach einmaliger und wiederholter Applikation beim Menschen.

The repeated administration of substances, which are mainly excreted by tubular secretion, can cause an increase of its own elimination. Because cephalothin is tubularly transported, it was of interest to prove, whether or not the repeated administration of therapeutic doses for 5 d produces an increases of renal elimination. Pharmacokinetic parameters show only small differences between the single and repeated dosing, caused by changes of volume of distribution. No stimulation of the carrier transport system was found. On the contrary, the renal elimination was reduced slightly after therapy for 5 d. Our results show that the present dosage recommendations are valid also for repeated administrations.

Pharmacokinetics and pharmacodynamic effects of furosemide in patients with liver cirrhosis.

Ten patients with compensated cirrhosis of the liver, 7 patients with portal decompensated cirrhosis of the liver and 10 patients with intact liver function were investigated. After intravenous injection of 40 mg furosemide elimination half-life, total and excretory clearance were not significantly different in the 3 groups investigated, but renal clearance was enhanced in the 2 cirrhosis groups and nonrenal clearance diminished in patients with decompensated cirrhosis of the liver. In those patients distributional volumes were significantly higher than in the control group. According to the increased urinary excretion of unchanged furosemide in patients with cirrhosis of the liver, the pharmacodynamic effect of the drug is enhanced: In the first 4-h-collecting period the excretion of water, chloride and sodium is significantly more increased than in the control group. After a period of 24 h this effect is still noticeable. The effect of furosemide on the excretion of potassium, creatinine and urea nitrogen is not significantly influenced by liver disease. Doubling the dose from 40 to 80 mg furosemide did not enhance the diuretic effect of the drug despite the doubled urinary excretion of unchanged furosemide.

[Urinary enzyme excretion in cephalothin therapy in pregnancy]. / Harnenzymausscheidung während einer Therapie mit Cephalothin in der Schwangerschaft.

A damage of the kidney, particularly of the proximal tubular cells, can be indicated by an increased concentration of distinct enzymes in urine. During cephalothin treatment of pyelonephritis in pregnant women the daily excretion of 4 brush-border enzymes was measured, to detect a tubulotoxic effect of this drug. The present results do not demonstrate a marked alteration of tubular cells. The use of cephalothin during pregnancy is possible, but the risk of nephrotoxic side effects should be considered.

[Determination of caffeine and metamizole elimination in pregnancy and after delivery as an in vivo method for characterization of various cytochrome p-450 dependent biotransformation reactions]. / Bestimmung der Elimination von Koffein und Metamizol in der Schwangerschaft und im Wochenbett als in vivo-Methode zur Charakterisierung verschiedener Zytochrom P-450-abhängiger Biotransformationsreaktionen.

The elimination of caffeine from plasma and the elimination of the main metabolites of metamizol in urine were measured in 20 pregnant women, 19 puerperants, and 10 young healthy female non-pregnant volunteers. It was found a significant prolongation of caffeine elimination in pregnancy (t 1/2 = 9.4 +/- 0.6 h) with a correlation between duration of pregnancy and elimination half-life of caffeine (v = 0.72). The amount of the main metabolites of metamizol eliminated 0-9 h after application of the drug decreased from 82.6 +/- 8.2 mg in nonpregnant volunteers to 45.6 +/- 5.7 mg in pregnant women. Whereas caffeine elimination is restored within the first week after delivery, the rate of metamizol elimination does not reach the value of the non-pregnant volunteers in this period.

[Determination of caffeine and metamizole elimination in men and women with and without hormonal contraceptives as an in vivo method for characterization of various cytochrome P-450 subspecies]. / Die Bestimmung der Coffein- und Metamizolelimination bei Männern und Frauen ohne sowie unter hormonalen Kontrazeptiva als in-vivo-Methode zur Charakterisierung verschiedener Cytochrom P-450 Subspezies.

Caffeine is mainly metabolized by 3-methylcholanthrene-inducible cytochrome P-450 (P-450MC) and noramidopyrine-methanesulfonate sodium (metamizol, Analgin) is mainly metabolized by phenobarbital-inducible cytochrome P-450 (P-450PB). We investigated the elimination of caffeine by the use of plasma concentration curves (HPLC) and the elimination of metamizol by spectrophotometric determination of the metabolites in urine in 10 healthy young males, in 10 healthy young females using no OL-steroids and in 10 healthy young females using OC-steroids. No influence of sex on the microsomal drug metabolism activity of these two drugs has been observed. There was a significantly decreased microsomal drug metabolism of both drugs in females under hormonal contraception. We conclude that OC-steroids decrease the demethylation activity of both P-450MC and P-450PB.

[The influence of galenic and biologic factors on the bioavailability of Berlocombin]. / Der Einfluss galenischer und biologischer Faktoren auf die Bioverfügbarkeit von Berlocombin.

The analysis of the influence of galenical and biological factors on the biological availability of Berlocombin (sulfamerazin and trimethoprim combination) has been performed by a single Berlocombin juice administration compared to tablets and by a tablet administration combined with nourishment. In case of the juice administration, the biological availability of trimethoprim and sulfamerazin has been reduced. The tablet administration at an empty stomach and a subsequent 5-h waiting period revealed a more complete trimethoprim resorption, which compared to an administration immediately after the standard breakfast is expressed by a significantly greater area under the concentration-time curve (AUC) in serum. In tablet application subsequent to a fatty breakfast, the trimethoprim and sulfamerazin resorption is compared to the relative group some increased; the differences, however, were insignificant ones. The results of this study failed to be of practical consequences, because the dosage applied and recommended by the producer significantly exceeded the minimum inhibition concentrations in serum and urine 3 h after administration. The required therapeutic level in no case fell short of up to the 12. hour.

Pharmacokinetic and pharmacodynamic effects of furosemide in patients with impaired renal function.

Three groups of patients with kidney diseases were investigated: I. creatinine in serum less than 100 mumol/l, II. creatinine in serum 100-250 mumol/l, III. creatinine in serum greater than 250 mumol/l. After intravenous injection of 40 mg and 80 mg furosemide, serum concentrations and urinary excretion of the unchanged drug were measured fluorometrically. Moreover, urinary excretion of water, electrolytes, creatinine and urea nitrogen were estimated in order to check the pharmacodynamic effect of the drug. The pharmacokinetic parameters calculated were similar in group I and II. In group III t 1/2 was prolonged, renal clearance of furosemide was diminished. The diuretic effect of furosemide was noticeable during the first 4 hours following the injection of 40 mg in all 3 groups. Doubling the dose did not enhance the effect. Creatinine and urea nitrogen excretion in urine were not influenced by furosemide.