The stimulative effect of diffusion potential on enoxacin uptake across rat intestinal brush-border membranes

Evidence of a membrane potential dependence for enoxacin uptake by rat intestinal brush-border membrane vesicles has been found. The transient overshooting uptake of enoxacin disappeared in the voltage-clamped brush-border membrane vesicles in the presence of an outward H(+)-gradient. Momentary dissipation of the H(+)-gradient itself by carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP) did not affect the uptake of enoxacin. In contrast, enoxacin uptake was depressed by an interior positive K(+)-diffusion potential induced by valinomycin. Furthermore, not only the outward H(+)-gradient but also an inward Cl(-)-gradient caused a stimulating effect on enoxacin uptake, and the stimulation by the Cl(-)-gradient was dissipated by using voltage-clamped membrane vesicles. These results indicate that enoxacin transportation across the brush-border membrane is dependent on the ionic diffusion potential. On the other hand, neither Gly-Gly nor guanidine had any effect on enoxacin uptake by the membrane vesicles in the presence of an inward (for Gly-Gly) or outward (for guanidine) H(+)-gradient as a driving force for each transport system. Therefore, it seems that enoxacin transport through the intestinal epithelia does not participate in the carrier-mediated transport systems for Gly-Gly and guanidine.

Enantioselective pharmacokinetics of homochlorcyclizine: disposition of (+)- and (-)-homochlorcyclizine after intravenous and oral administration of racemic homochlorcyclizine to rats

Concentrations of homochlorcyclizine enantiomers in blood, urine, and tissues of the liver, lung, kidney, brain, heart, spleen, intestine and stomach of rats after drug administration were determined by high-performance liquid chromatography on a chiral stationary phase. After intravenous administration (10 mg kg-1), homochlorcyclizine was rapidly distributed in many tissues, with the highest concentration in lung. No differences were found between enantiomers in blood concentrations. After oral administration (50 mg kg-1), the concentrations of the (+)-isomer in nearly all tissues were higher than those of the (-)-isomer. The AUC0-infinity values of the (+)- and (-)-isomers differed significantly. The absorption of racemic homochlorcyclizine from rat small intestine was not enantioselective. These results suggested that the different concentrations between enantiomers after oral administration were not caused by enantioselective absorption or distribution but rather by preferential first-pass metabolism of the (-)-isomer in the liver. The enantioselectivity of metabolism was also demonstrated by in-vitro experiments.

Effect of membrane surface potential on the uptake of anionic compounds by liposomes

The effect of membrane surface potential on the uptake of several anionic compounds by liposomes (large unilamellar vesicles), which contain various amounts of dipalmitoylphosphatidylserine (DPPS), was investigated. The uptake amount of four tested anionic compounds (cefixime, benzyloxyindoleacetic acid (BOIAA), ceftibuten and S-1006) decreased with an increase in the DPPS content of liposomes, and was correlated with the membrane surface potential monitored using a fluorescent dye, 8-anilino-1-naphthalene sulfonate (ANS). Moreover, for all of the tested anionic compounds, a good correlation was observed between the ratio of the uptake value (5 min) by each of the liposomes comprising various amounts of DPPS to the uptake value by liposomes containing 10% DPPS and a relative membrane surface potential monitored by ANS. On the other hand, the uptake of zwitterionic compounds (enoxacin, cephradine and benzyloxytryptophan (BOTP)) was independent of DPPS content. These results suggest that the uptake of tested anionic compounds by large unilamellar lipid vesicles is dependent on the membrane surface potential which originates in the surface negative charge.

An epidemiologic analysis of end-stage lupus nephritis

We analyzed 566 patients (515 females and 51 males) with systemic lupus erythematosus who were treated in Okinawa, Japan, from 1972 to 1991 and followed until April 1993. One hundred four patients (95 females and 9 males) died, and 51 were considered to have end-stage lupus nephritis. The annual incidence and prevalence, per million population in each sex, were increased from 16.0 and 66.0 in 1972 to 46.7 and 683.9 in 1991 in the female patients, and from 4.2 and 8.3 in 1973 to 8.3 and 70.0 in 1991 in the male patients, respectively. Cox proportional hazard analysis was done to determine the effects of several covariates on patients and renal survival. The patients' survival rate improved, as the hazard ratio (HR) was decreased to 0.69 (year of diagnosis, 1982 to 1986) and to 0.48 (year of diagnosis, 1987 to 1991) when the HR in patients diagnosed before 1981 was taken as 1.00. Similarly, we examined renal survival by using the Cox proportional model. For this analysis, the date of start of dialysis therapy was regarded as the time of renal death. Male patients had significantly poor renal survival; the HR was 3.64 (95% confidence interval, 1.89 to 6.98) when the HR in the females was taken as 1.00. However, age at diagnosis and year of diagnosis did not significantly affect renal survival. The cumulated incidence of end-stage lupus nephritis from the time of diagnosis of systemic lupus erythematosus was 3.1% at 5 years, 9.4% at 10 years, 15.5% at 15 years, and 21.0% at 20 years.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of Enterued administration on the intestinal absorption of orally active cefem antibiotics]

The effect of simultaneous administration of Enterued, an elemental diet, which is composed of oligopeptides (egg white hydrolyzate), on the orally active cefems was investigated. Ceftibuten (CETB) administered together with Enterued to man was excreted slower in the urine. AUC from the plasma concentrations of CETB after the oral administration with Enterued was markedly decreased compared to that without Enterued in rat. In contrast, neither urinary excretion of cephalexin (CEX) in man nor the AUC from the plasma profile of CEX in rat was changed by Enterued. Furthermore, the disappearance, tissue accumulation, net absorption of CETB from the rat jejunal loop were significantly inhibited by Enterued. However, the net absorption of CEX has no alternation in the presence of Enterued, although the apparent disappearance decreased on the basis of the diminishment of tissue accumulation. Additionally, Hepan ED, which is an elementary diet composed of amino acids, and the mineral solution containing neither peptides nor vitamins have also exhibited the decreasing effect on the CETB absorption behaviour. These results suggested that the inhibitory effects of Enterued on the absorption of these antibiotics were not due to the inhibition of peptide-transport systems.

Changes in the permeation rate of organic anions through the intestinal brush-border membrane with membrane surface potential

The effects of membrane surface potential on the uptake of anionic compounds by rat intestinal brush-border membrane vesicles were investigated. The uptake amount of all tested anionic compounds (ceftibuten, cefixime, benzylpenicillin, s-1006 and rentiapril) in the neutral medium (pH 7.5) was lower than that in the acidic medium (pH 5.5). Changes in surface potential of brush-border membrane vesicles were monitored using a fluorescence dye, 8-anilino-1-naphthalenesulfonate (ANS), and the results suggested an increase of a negative charge on the membrane surface proportional to the increase of the pH of medium. A good correlation was observed between the initial uptake rate of all tested anionic compounds and relative membrane surface potential monitored by ANS. Moreover, the uptake of cefixime by artificial liposome made from PC containing various amount of DPPS was measured. The uptake value of cefixime was decreased in proportion to an increase of DPPS content. These results suggest that the permeation of anionic compounds across intestinal brush-border membrane is dependent on surface potential originate in the surface negative charge.

Effect of renal diseases and comorbid conditions on survival in chronic dialysis patients

International and geographical differences in the survival rates of chronic dialysis patients can be explained by differences in primary renal disease, in the acceptance rate of elderly patients, and in predialysis comorbid conditions. Several studies have shown the effects of these factors on survival. However, in most studies, a large number of patients may leave for renal transplantation or transfer to other centers, so that precise analysis becomes impossible. Although the number of patients in our registry is not so large (n = 1,982), we have few such problems and were able to examine the effects of the above-mentioned factors on patient survival using the Cox proportional hazard model. Hazard ratios (HR) and 95% confidence intervals were 0.739 and 0.366-1.491 in patients with polycystic kidney disease (n = 38), 2.669 and 1.513-4.708 in patients with systemic lupus erythematosus (n = 39), 1.245 and 0.935-1.660 in patients with nephrosclerosis (n = 122), 1.815 and 1.447-2.229 in patients with diabetes mellitus (n = 374), and 1.595 and 1.201-2.117, respectively, in patients with other renal diseases (n = 146) when the HR in patients with chronic glomerulonephritis (n = 1,263) was taken as 1.00. HR and 95% confidence intervals were 1.222 and 1.016-1.470 in patients with one comorbid condition (n = 217) and 1.494 and 1.033-2.160, respectively, in patients with two comorbid conditions (n = 24) when the HR of patients with no predialysis comorbid conditions (n = 1,741) was taken as 1.00. Our data demonstrate the effects of renal diseases and number of predialysis comorbid conditions on the survival in chronic dialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for high risk of cerebral hemorrhage in chronic dialysis patients

One-half of the total deaths in chronic dialysis patients are due to cardiovascular disease; however, the precise incidence and relative risk of those compared to normals are not known. Therefore, we sought to determine the annual incidence of cardiovascular disease and relative risk of those on chronic dialysis to the general population. Both the general population (1.2 million, Census 1990) and chronic dialysis patients (N = 1,609) in Okinawa, Japan were studied prospectively from April, 1988, to March, 1991. Diagnosis of stroke was made by symptoms and brain CT scan, and acute myocardial infarction was done by changes in electrocardiogram and serum enzymes. The relative risk (observed/expected ratio) was calculated by using the standardized morbidity rate obtained in both sexes and age-class every 10 years in the general population. Forty-one stroke (8 cerebral infarction, 31 cerebral hemorrhage, and 2 subarachnoid hemorrhage) and four acute myocardial infarction cases were registered during the study period in chronic dialysis patients. The incidence per 1,000 person-year was 11.5 in stroke, 2.2 in cerebral infarction, 8.7 in cerebral hemorrhage, 0.6 in subarachnoid hemorrhage, and 1.1 in acute myocardial infarction. The relative risk compared to normals was 5.2 in stroke, 2.0 in cerebral infarction, 10.7 in cerebral hemorrhage, 4.0 in subarachnoid hemorrhage, and 2.1 in acute myocardial infarction. Cerebral hemorrhage occurred at 10 years younger than that of the general population (P < 0.001) and was associated with high prevalence of hypertension and low levels of serum albumin and cholesterol. Our results confirm the importance of blood pressure control and nutritional status in chronic dialysis patients.

The transport mechanisms of organic cations and their zwitterionic derivatives across rat intestinal brush-border membrane. II. Comparison of the membrane potential effect on the uptake by membrane vesicles

Further investigation of organic cation transport mechanisms were continued using rat intestinal brush-border membranes following our previous report. The net uptake of organic cations was superior to that of their zwitterionic derivatives. This result agreed with the absorption behaviour of these compounds from rat intestinal loop. The uptake of tyramine and 5-benzyloxytryptamine was significantly stimulated by the valinomycin-generated K(+)-diffusion potential (inside-negative). On the other hand, the uptake of zwitterionic derivatives was not affected by the valinomycin-induced K(+)-diffusion potential. The voltage-clamped brush-border membrane vesicles exhibited a complete disappearance of the overshoot-uptake of organic cations. Therefore, this permeation mechanism across the intestinal brush-border membrane seems to be different from the well-known H(+)-antiport system of organic cation found in other organs such as kidney and liver, and depends upon an inside-negative H(+)- or K(+)-diffusion potential.

The diversity of Na(+)-independent uptake systems for polyamines in rat intestinal brush-border membrane vesicles

Na(+)-independent uptake rate and binding to the membrane surface of polyamines (spermine, spermidine and putrescine) have been characterized using rat small intestinal brush-border membrane vesicles. The uptake of spermine and spermidine was saturable (Km = 30.4 microM and 148.1 microM, respectively), however, putrescine uptake was not saturable up to 8 mM. In contrast, the values of binding to the membrane surface of all polyamines were not saturable in the present studies. In Dixon plot analysis, spermine competitively inhibited the uptake rate of spermidine with a Ki value of 33.8 microM, while the putrescine inhibitory effect on the spermidine uptake rate was non-competitive (Ki = 3.28 mM). These uptake systems were not affected by the valinomycin-induced K(+)-diffusion potential (inside negative). These results suggested that there were two different Na(+)-independent uptake systems for spermine and spermidine, as well as for putrescine, on this membrane. However, they were not the same as the electric potential-dependent uptake system for monocationic compounds. Furthermore, this uptake system for spermine and spermidine might not be a carrier protein, because the intravesicular spermine exhibited no trans-stimulation effect on the uptake of spermidine.

Evidence for increased cancer deaths in chronic dialysis patients

We analyzed longitudinal data on the cancer mortality rate in chronic dialysis patients and in the general population in Okinawa, Japan. In the general population from 1980 to 1990, the mortality rate has been stable at approximately 1.300 males and 0.897 females per thousand persons year, the male to female ratio being 1.45. In the period from 1971 to 1990, we found 91 (4.6%) patients with cancer in a group of 1,982 (824 females and 1,158 males) chronic dialysis patients; forty-nine of the 91 patient (53.8%) died by April 1, 1991. Using the standard mortality rate in the general population, which was obtained for each sex and age class (0 to 34 years, 35 to 44 years, 45 to 54 years, 55 to 64 years, and > or = 65 years), we calculated the relative risk of death from cancer in dialysis patients. The risk ratio in dialysis patients was significantly increased, being 2.48 (P < 0.05) for males and 3.99 (P < 0.05) for females. The mean (+/- SEM) age at the time of death from cancer in the dialysis group was 60.1 +/- 2.0 years in the males and 60.1 +/- 2.1 years in the females; the males were 6.3 years younger than the general population and the females were 9.3 years younger. The proportion of patients with colon cancer (both sexes) and cancer of the uterus and breast (females) was higher in the dialysis patients than in the general population.

Serum albumin is a strong predictor of death in chronic dialysis patients

We examined the predictive value of various clinical variables in assessing survival in chronic hemodialysis patients (N = 1,243, 524 females, 719 males) who were under treatment with hemodialysis as of January 1991 in Okinawa, Japan and who were followed up until April 1992. Basal clinical data such as sex, starting date of dialysis, primary renal disease, blood pressure, blood chemistry values, and dialysis prescription data obtained just prior to dialysis were registered at the start of the study. As of the end of April 1992, 104 had died, 16 were transplant recipients, and five had been transferred. Those who died had significantly lower levels of total protein, serum albumin, total cholesterol, triglyceride, BUN, serum creatinine, body weight, body height, diastolic blood pressure, and duration of hemodialysis than those who survived. Older patients and those with diabetes mellitus had a poorer prognosis. A forward stepwise logistic procedure by SAS was used to determine the predictive value of the above clinical variables. With the addition of laboratory variables, the predictive value of diabetes was lost, as the diabetic patients had low serum levels of albumin and creatinine. The standardized coefficient was -0.380 (P = 0.0001) at age of entry, 0.316 (P = 0.0001) for serum albumin, 0.280 (P = 0.0001) for serum creatinine, 0.138 (P = 0.043) for body mass index (BMI), and -0.139 (P = 0.016) for male sex. The prescribed dialysis dose (M2 hr per week) was significantly correlated with serum creatinine (r = 0.48, P = 0.0001), serum albumin (r = 0.135, P = 0.0001) and BMI (r = 0.275, P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Transport characteristics of paraquat across rat intestinal brush-border membrane

The mechanism of absorption of paraquat, which is a type of quaternary ammonium compound (QAC), was studied using rat intestinal loops and brush-border membrane vesicles. Approximately 47% and 37% of radioactively labeled paraquat injected into jejunal and ileal loops disappeared, respectively, after 60 min. Since only a small amount of radioactivity was detected in the mucosal fraction, most of the paraquat that disappeared from the intestinal lumen was considered to have been carried away by the bloodstream, indicating that paraquat absorption was greater than expected. In spite of its low lipid solubility, the uptake of paraquat by brush-border membrane vesicles reflected smooth penetration into the intravesicular space rather than binding to the membrane. According to the increase in extravesicular paraquat concentration, paraquat uptake in the early stage was saturable. Moreover, early paraquat uptake was significantly inhibited by structurally-related QACs such as tetramethylammonium and choline, but not by an endogenous dicationic amine (putrescine). On the other hand, inside-negative membrane potential had no significant effect on the time course of paraquat uptake. From these results, it is suggested that paraquat is absorbed through a specialized mechanism associated with the carrier-mediated transport system for choline on the brush-border membrane.

Comparing the cell population on different intraocular lens materials in one eye

We developed a method to evaluate cell adherence to different intraocular lens (IOL) materials in one eye in which we coated one half of the anterior surface of a poly(methyl methacrylate) (PMMA) IOL with poly(dimethyl siloxane), a silicone material. The lenses were implanted in the anterior chamber of rabbit eyes without lens extraction. Postoperative cellular reaction on the IOL surfaces was studied by specular microscopy. The IOLs were fixed in situ, removed from the eyes, and stained with hematoxylin-eosin so we could evaluate the cell population on the silicone and PMMA surface. Fewer cells were scattered on the silicone surface than on the PMMA surface. This method excludes surgical effects and allows a comparison of various IOL materials in the same eye.

The transport mechanism of an organic cation, disopyramide, by brush-border membranes. Comparison between renal cortex and small intestine of the rat

The characteristics of disopyramide uptake in brush-border membrane vesicles isolated from rat renal cortex and small intestine were investigated. Transport of disopyramide into an osmotically reactive intravesicular space was observed with notable binding to the membrane surface. An outwardly directed H+ gradient stimulated disopyramide uptake, resulting in a transient uphill transport in both brush-border membranes. As for the renal brush-border membrane, the H+ gradient itself appeared to be the driving force for this stimulation of uptake. These findings suggest that disopyramide-H+ antiport is the mechanism of disopyramide action in renal cell membrane. The initial uptake was saturable (Km and Vmax of 68.0 microM and 1.25 nmol (mg protein)-1/30 s, respectively). The stimulation of disopyramide uptake by an outward H+ gradient in rat intestinal brush-border membrane was due to an interior negative H(+)-diffusion potential. A K(+)-diffusion potential (interior negative) enhanced disopyramide uptake. These results suggest that there are different mechanisms of disopyramide uptake for renal and intestinal brush-border membrane vesicles.

Enantioselective pharmacokinetics of homochlorcyclizine. III. Simultaneous determination of (+)- and (-)- homochlorcyclizine in human urine by high-performance liquid chromatography

A method is described for the simultaneous determination of (+)- and (-)-homochlorcyclizine (HCZ) in human urine by high-performance liquid chromatography on a chiral stationary phase of ovomucoid-bonded silica. The pH of the buffer and organic modifier in the mobile phase markedly affected the chromatographic separation. A mobile phase of methanol-0.02 M acetate buffer (pH 4.7) (25:75,v/v) at a flow-rate of 1.0 ml/min was used for the urine assays. The ultraviolet absorption was monitored at 240 nm, and diphenhydramine was employed as the internal standard for the quantitation. (+)-HCZ, (-)-HCZ and the internal standard were eluted at retention times of 15, 25 and 8 min, respectively. The limit of determination for HCZ enantiomers was ca. 50 ng/ml of urine. One of the metabolites in human urine, which was a quaternary ammonium-linked glucuronide, could also be determined in a manner similar to unchanged HCZ after beta-glucuronidase hydrolysis. A pharmacokinetic study was conducted with three healthy volunteers, who each received a single oral dose of racemic HCZ (20 mg). Distinct differences were found between the two enantiomers, particularly in the metabolic process, that is, the urinary excretion as (-)-HCZ-glucuronide within 48 h was ca. four times higher than that of the (+)-isomer. This method should be very useful for enantioselective pharmacokinetic studies of HCZ.

The transport mechanisms of organic cations and their zwitterionic derivatives across rat intestinal brush-border membrane. 1. Binding characteristics to the bio- and lipid-membranes

The uptake mechanisms of organic cations such as tryptamine, tyramine, 5-benzyloxytryptamine (BOTA) and their zwitterionic derivatives (tyrosine, tryptophan, 5-benzyloxytryptophan (BOTP)) by rat intestinal brush-border membrane vesicles and liposome containing phosphatidylserine were studied and compared. As compared to their zwitterionic derivatives, uptake rates by rat intestinal brush-border membrane of these three cations were far superior. The binding of cationic compounds to the brush-border membrane was also higher than those of their zwitterionic derivatives. Furthermore, the binding behaviour of BOTA and tryptamine to phospholipid liposome clearly amplified with increasing amounts of phosphatidylserine. In contrast, the contents of phosphatidylserine, a negatively charged phospholipid, exhibited no effects on the binding of zwitterionic derivatives (tryptophan and BOTP). The double-reciprocal plot of tryptamine binding with BOTA to liposome showed competitive inhibition. These results suggest that the binding of organic cations to the membrane lipid has a relatively high specificity despite the absence of membrane protein such as a transport-carrier in the liposome, and that the binding of cationic compounds play an important role in the uptake to the cell membrane systems.

Survival analysis of dialysis patients in Okinawa, Japan (1971-1990)

We analyzed longitudinal data obtained from the initiation of chronic dialysis in Okinawa, Japan. A total of 1,982 patients (824 females and 1,158 males) were registered in the Okinawa Dialysis Study (OKIDS) up to the end of 1990. The number of patients dying, undergoing renal transplantation, or being transferred was 605 (30.5%), 75 (3.8%), and 23 (1.2%), respectively. The mean acceptance rate per million population increased from 19.7 in 1971 to 1975 to 157.4 in 1986 to 1990. The percentage of diabetic patients and the annual gross mortality rate were, respectively 0% and 0.52 (1971 to 1975), 7.3% and 0.12 (1976 to 1980), 14.4% and 0.06 (1981 to 1985), and 24.6% and 0.07 (1986 to 1990). Cox proportional hazard analysis was used to determine the relative risk (RR) for sex, primary renal disease, age at entry, and the year of starting dialysis. The RR for males was 1.09 (1.00 for females) and the 95% confidence interval (CI) was 0.93 to 1.28. The RR for diabetics was 1.88 (95% CI; 1.55 to 2.28) when that for nondiabetics was set at 1.00. The RR (95% CI) for starting dialysis in 1976 to 1980, 1981 to 1985, and 1986 to 1990 was 0.65 (0.59 to 0.72), 0.43 (0.35 to 0.52), and 0.28 (0.20 to 0.38), respectively, when the RR in 1971 to 1975 was taken as 1.00. During the last two decades, the survival of chronic dialysis patients in Okinawa has continued to improve despite the large increase in acceptance rate, the older age of the new patients, and the increase in diabetic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

[Pharmacokinetic and clinical studies of cefditoren pivoxil in the pediatric field. Pediatric Study Group of ME1207]

Cefditoren pivoxil (ME1207) in granules, a new oral cephalosporin, was pharmacokinetically and clinically evaluated in the pediatric field and the following results were obtained: 1. Pharmacokinetics In infants administered single oral doses of 3 mg (potency)/kg and 6 mg/kg, the Cmax was 1.54 +/- 0.68 and 2.85 +/- 1.03 micrograms/ml; Tmax, 2.27 +/- 1.08 and 2.06 +/- 1.16 hours; T 1/2, 2.22 +/- 1.95 and 1.68 +/- 0.66 hours; and AUC (0-infinity), 7.43 +/- 3.68 and 11.90 +/- 4.51 micrograms.hr/ml, respectively. These values have indicated that the drug has a dose-dependent pharmacokinetic behavior. Urinary concentrations peaked in 2-4 hours after administration. Urinary recovery rates in the first 8 hours were 19.4 +/- 6.6% at 3 mg/kg and 17.1 +/- 5.2% at 6 mg/kg. 2. Clinical results The clinical efficacy of the drug was evaluated in 445 patients with various infections. Cefditoren pivoxil was administered at daily doses of 9-18 mg/kg divided into 3 equal doses to most patients. Daily doses of > 7.5-10.5 mg/kg were given to 48.8% of the patients. The overall clinical efficacy rate was 97.3%, and this drug was effective in 97.5% of the 319 patients for whom the causative pathogens were identified and in 96.8% of the 126 patients with infections for whom the causative pathogens were unknown. The efficacy rate at daily doses of > 7.5-10.5 mg/kg was 97.2%, similar to that obtained at daily doses of > 10.5-19.5 mg/kg (97.0%). The bacteriological eradication rate was 90.4%. The efficacy and eradication rates for 66 patients who had not responded to previous chemotherapy were 95.5% (63/66) and 89.4%, respectively. Side effects occurred in 19 (4.2%) of 456 patients subjected to safety analyses. The primary side effect was diarrhea but no serious side effects were noted. As abnormal laboratory test results, moderate increases of the eosinophils and platelets counts as well as moderate elevations of the transaminases were observed. These abnormalities are also seen with other cephems and to a similar extent. No particular and serious problems were associated with administration of this drug. Based on the above results, cefditoren pivoxil is considered to be very useful at a dose level of 3 mg/kg t.i.d. against most infections encountered in the pediatric field.

Carbamazepine-induced hyponatremia in a patient with partial central diabetes insipidus

A 51-year-old Japanese man was referred for the evaluation of persistent hyponatremia. The serum sodium level remained around 120 mmol/l despite mild water restriction. His past history included chronic alcoholism, myocardial infarction and lumbar disc herniation. Carbamazepine (200 mg, b.i.d.) has been used for more than 8 years for low back pain. Serum sodium returned to normal after carbamazepine was stopped, and rechallenge produced acute symptomatic hyponatremia (117 mmol/l) on day 2 after a total dose of 600 mg. Hepatic, renal and endocrine function were within normal limits, and the response to a water load (20 ml/kg) was also normal. Partial central diabetes insipidus was diagnosed by his response to water restriction and nasal desmopressin administration. Polyuria and hypernatremia were not evident in this case, probably due to a combination of low solute intake and low, but not deficient, levels of plasma ADH. This case demonstrates that carbamazepine may cause acute hyponatremia even in central diabetes insipidus, probably by sensitizing the distal renal tubules.

Carrier-mediated transport system for choline and its related quaternary ammonium compounds on rat intestinal brush-border membrane

The characteristics of the intestinal transport system for choline were investigated using isolated brush-border membrane vesicles from rat small intestine. In spite of the diminutive lipid solubility, the uptake of choline by membrane vesicles reflected smooth permeation into intravesicular space rather than the binding to the membrane surface. Physiological conditions, present in the intact intestine, such as an inward-directed Na+ or H+ gradient and inside negative membrane potentials, didn't directly involve in choline transport across the brush-border membrane. Moreover, an outward-directed H+ gradient had no significant effect on the time course of choline transport. However, in the absence of a driving-force, the initial uptake of choline exhibited a saturable manner. A kinetic analysis of the initial uptake rate gave an apparent Km of 159 microM. Furthermore, unlabeled choline caused both cis-inhibition and trans-stimulation for labeled choline transport, suggesting the existence of a carrier-mediated transport system for choline, classified as so-called 'facilitated diffusion'. Since tetramethylammonium, acetylcholine, and N1-methylnicotinamide caused both cis-inhibition and trans-stimulation, they appear to be accepted as the substrate of choline carrier. On the other hand, quaternary ammonium compounds (QACs) such as those which possessed hydrophobic parts in their molecules exhibited only cis-inhibition. They also inhibited Na(+)-dependent D-glucose transport, indicating that they influenced various carrier-mediated transport systems non-specifically due to interaction with the membrane. These findings strongly suggest that the choline transport system on the brush-border membrane of rat intestine recognizes only small molecular QACs as its substrate.

Membrane-potential-dependent uptake of tryptamine by rat intestinal brush-border membrane vesicles

The effect of membrane potential on the uptake of tryptamine, an organic cation, by rat intestinal brush-border membrane vesicles was studied. In the presence of an outwardly directed H(+)-gradient, the initial uptake of tryptamine was stimulated remarkably and the overshoot phenomenon was observed. In contrast, the uptake was depressed by an inwardly-directed H(+)-gradient. The effect of H(+)-gradient on the uptake of tryptamine was maintained in the presence of FCCP, whereas it vanished when voltage-clamped vesicles were used. Moreover, the uptake of tryptamine was linearly augmented with increase of the valinomycin-induced inside-negative K+ diffusion potential. These results suggest that tryptamine is taken up into intestinal brush-border membrane vesicles depends upon the ionic diffusion potential. The effect of several indole derivatives and amine compounds on the uptake of tryptamine was also examined. The uptake of tryptamine was inhibited by all amine compounds used, but anionic and zwitterionic compounds had no effect, suggesting that these amines interact on brush-border membrane and cause an inhibitory effect.

Rapid and simple method for the determination of alpha 1-acid glycoprotein in serum by column liquid chromatography

A rapid and simple method for the determination of alpha 1-acid glycoprotein (AAG) in serum was developed by using an anion-exchange column for clean-up of serum and a hydroxyapatite column for high-performance liquid chromatography (HPLC). A good correlation was observed between this HPLC method and the conventional radial immunodiffusion method. The method may also be used to determine the AAG concentration in the serum of experimental animals.

Enantioselective pharmacokinetics of homochlorcyclizine II: disposition and metabolism of (+)-, (−)- and racemic homochlorcyclizine after oral administration to man

The pharmacokinetics of a single oral dose of 20 mg (+)-, (-)- and racemic homochlorcyclizine (HCZ) have been studied in humans. The formation of the quarternary ammonium-linked glucuronide was an important metabolic pathway, and the metabolic process was enantioselective as a result of differing urinary excretion rates of (+)-, (-)- and racemic glucuronide. There were significant differences between (+)-, (-)- and racemic HCZ in AUC (0-14 h) and plasma protein binding, but all HCZ enantiomers were slowly absorbed and eliminated (elimination half-lives about 11 h). The results shows help to establish a more efficient dosage regimen for HCZ therapy.

Comparison of disposition behavior and de-coppering effect of triethylenetetramine in animal model for Wilson's disease (Long-Evans Cinnamon rat) with normal Wistar rat

The disposition behaviors and de-coppering effect of triethylenetetramine dihydrochloride (trientine), a selective chelating agent for copper and an 'orphan drug' for Wilson's disease, have been evaluated in an animal model, Long-Evans Cinnamon (LEC) rats, and normal rats (Wistar). In LEC rats, urinary excretion of trientine was remarkably lower than that of Wistar rats. The absorption rates from the jejunal loop and in vitro metabolism in the liver S9 fraction (supernatant of 9000 x g) were approximately the same for both strains. The decline of urinary excretion of trientine in LEC rats is thought to be due mainly to the lowering of the functional activity of the kidney, because urinary excretion of creatinine and phenolsulfonphthalein were significantly lower in LEC rats than those in Wistar rats. Both acceleration of urinary excretion of copper and reduction of hepatic copper levels were observed with treatment of trientine in LEC rats aged 6 weeks. In LEC rats aged 13 weeks, however, no de-coppering effect from the liver was observed, though urinary excretion of copper was increased. These results suggest that trientine has a pharmacological effect in disease state, especially in the early stages of hepatitis.

Absorption of acetylsalicylic acid from the rat nasal cavity

The fate of salicylate in the plasma of rats was followed after nasal, intravenous, and oral administration of 2.0-mg doses of aspirin. Aspirin was well absorbed following nasal administration of a neutralized, nonirritating solution containing triethanolamine. The rate of absorption was slower than that of other nasally administered drugs, such as propranolol or progesterone. The bioavailability of aspirin following nasal administration was 100%, whereas the oral bioavailability was only 58.8% at the dose studied.

Uptake characteristics of polyamines into rat intestinal brush-border membrane

The uptake characteristics of polyamines, such as spermine, spermidine and putrescine, have been investigated using brush-border membrane vesicles isolated from the small intestine of rats. The uptake of these polyamines into the membrane vesicles was high and the order of uptake was spermine greater than spermidine greater than putrescine at medium pH 7.5, respectively. The medium pH considerably affected the uptake of these polyamines and the amount of uptake increased remarkably with an increase of the medium pH (pH 7.5 or 8.0 greater than pH 5.5). An inward Na+ gradient did not stimulate the uptake rate of any of these polyamines. We have also examined the binding behaviour to the membrane lipid, phospholipids and total lipid, and there was a good correlation in the binding properties, pH-dependency and uptake activity, between the liposomes and brush-border membrane vesicles. These results suggest that the uptake of the polyamine into the vesicles consisted of rapid binding to the outside intestinal surface and slower binding to the inside membrane after permeation. Furthermore, findings from experiments concerning the mutual inhibition among these polyamines and concerning the effect of other polycations, having 2-5 amines in number, on the uptake of spermine, suggest that the number of amino groups in the polyamine molecules plays an important role in the uptake process into the brush-border membrane vesicles.

A case of syndrome of inappropriate secretion of antidiuretic hormone (SIADH) with low plasma concentrations of antidiuretic hormone

A 66-year-old Japanese man presented with persistent hyponatremia without polydipsia and polyuria. Laboratory examination showed serum sodium of 117 mEq/l, plasma osmolality 239 mosm/kg, urine sodium 108 mEq/l, urine osmolality 577 mosm/kg, and normal levels (less than 2.0 pg/ml) of serum antidiuretic hormone (ADH). ADH release was regulated normally with changes in plasma osmolality. No obvious cause for the syndrome of inappropriate secretion of ADH (SIADH) could be detected. However, 20 months later, the patient had bouts of hematuria and was found to have cancer of the urinary bladder. Increased renal sensitivity to ADH was suspected as the underlying mechanism of SIADH.

Method for Optical Resolution of Racemic Homochlorcyclizine and Comparison of Optical Isomers in Antihistamine Activity and Pharmacokinetics

A method was developed for semi-preparative scale enantioseparation of racemic homochlorcyclizine (HCZ) by high performance liquid chromatography (HPLC) on Chiralcel OD column. The best resolution was achieved using an eluent composed of n-hexane plus 0.2 M isopropylamine. By this method, about 5.0 mg of racemic HCZ could be resolved completely in one run. The optical purity of the enantiomers were both greater than 99.9%. The studies of antihistamine activity on guinea pig ileum demonstrated that l-HCZ is significantly more potent than d- and racemic HCZ. The pharmacokinetics of d- and l-HCZ after oral administration to rats also differed. The successful resolution of racemic HCZ permits comparison of the pharmacokinetics and antihistamine activity of the enantiomers.

Chronic hypovolemia associated with accelerated hypertension and orthostatic hypotension in a patient on continuous ambulatory peritoneal dialysis

We report a patient with nondiabetic end-stage renal disease on continuous ambulatory peritoneal dialysis (CAPD) associated with chronic hypovolemia. Despite the administration of nilvadipine, the patient showed accelerated hypertension and concomitantly orthostatic hypotension. Plasma renin activity was markedly high, and blockade of angiotensin II action by captopril or an angiotension II antagonist decreased the supine blood pressure. This indicated that the enhanced activity of the renin-angiotensin system was the principal cause of the supine hypertension. The plasma concentration of norepinephrine was also very high. After correction of hypovolemia by blood transfusion, the enhancement of the renin-angiotensin system and high plasma norepinephrine level were reduced, and symptomatic orthostatic hypotension disappeared. The accelerated hypertension was easily controlled by the administration of low-dose captopril and nilvadipine. These findings suggest that chronic hypovolemia related to the intractable supine hypertension as well as orthostatic hypotension. Hypovolemia-induced enhancement of the renin-angiotensin system and sympathetic nerve activity may cause vasoconstrictive hypertension in patients on CAPD.

Elevation of serum erythropoietin after subtotal parathyroidectomy in chronic haemodialysis patients

After successful subtotal parathyroidectomy (PTX) in 10 chronic haemodialysis patients, significant elevation of Epo was observed, from 48.4 +/- 17.8 mU/ml(M +/- SEM) at preoperative state to 103.3 +/- 34.7 mU/ml at 6 h and 163.4 +/- 50.2 mU/ml at 12 h after PTX. Significant reductions in both PTH-m and ionized calcium (iCa) were confirmed. Since Epo did not increase in the cases with an inadequate PTX and ovariectomy, an abrupt reduction in PTH with a decrease in iCa may play some role in the elevation of Epo.

Transport characteristics of ceftibuten, cefixime and cephalexin across human jejunal brush-border membrane

The transport characteristics of orally active cephalosporins, ceftibuten, cefixime and cephalexin have been examined using brush border membrane vesicles isolated from human jejunum. In the initial uptake of ceftibuten, the stimulation and overshoot phenomena were observed in the presence of an inward H+ gradient. Effects of H+ gradient on the uptake of cefixime and cephalexin were low and no overshoot was observed. These transport characteristics, especially uphill transport phenomena, were in agreement with previous results obtained from rat intestinal brush-border membrane vesicles and suggest that these beta-lactam antibiotics are absorbed by different transport systems, despite their similar molecular structures.

Gastrointestinal absorption of quaternary ammonium compounds correlated to their binding to small intestinal brush border membrane in rat

The relationship between absorption of quaternary ammonium compounds (QACs) from rat intestine and their in-vitro binding to isolated brush-border membrane has been examined, using a series of n-alkyltrimethylammoniums. The binding of these QACs gradually increased with each extension of unbranched hydrocarbon chain from octyltrimethylammonium to tetradecyltrimethylammonium. However, hexyltrimethylammonium and heptyltrimethylammonium failed to bind to the membrane. On the other hand, the disappearance of these QACs from rat jejunal loop also increased with the length of hydrocarbon chain over the range of 8.9 to 71.3%. A good correlation was found between binding to the brush-border membrane and disappearance from jejunal loop. From these results, it was suggested that the size of the hydrophobic part of a QAC molecule was a principal determinant of both absorption and membrane binding, and that the absorption of QACs with an appropriate sized hydrophobic part, was closely associated with the degree of binding to the membrane.

[Pharmacokinetic and clinical studies of cefdinir in the pediatric field. Pediatric Study Group of Cefdinir]

We studied pharmacokinetics and clinical effects of 5% and 10% fine granules of cefdinir (FK 482, CFDN), a new oral cephalosporin, in the pediatric field and the following results were obtained. 1. Pharmacokinetics (blood concentration and urinary excretion) Pharmacokinetics of CFDN in 163 children was investigated. Cmax and T 1/2 were 0.92 +/- 0.45 micrograms/ml and 1.95 +/- 1.06 hours, respectively, in the fasting state, and were 0.63 +/- 0.29 micrograms/ml and 2.26 +/- 0.65 hours, respectively, in the non-fasting state, at a dose level of 3 mg (potency)/kg. At a dose level of 6 mg (potency)/kg, Cmax and T 1/2 were 1.29 +/- 0.49 micrograms/ml and 2.11 +/- 1.85 hours, respectively, in the fasting state and were 1.28 +/- 0.48 micrograms/ml and 2.01 +/- 0.84 hours, respectively, in the non-fasting state. Data of Cmax and AUC showed that blood concentration of the drug depended on dose levels. Urinary recovery rates in the first 8 hours were 20.5 +/- 8.8% in the fasting state and 14.8 +/- 5.9% in the non-fasting at a dose level of 3 mg (potency)/kg and 16.5 +/- 6.7% and 17.8 +/- 2.4%, respectively, at 6 mg (potency)/kg. 2. Clinical effects Clinical effects of CFDN on various infections were studied in 612 children who were treated with 5% fine granules of CFDN (5% granule group) and in 208 with 10% fine granules of CFDN (10% granule group). CFDN granules were administered mainly at daily doses of 9.0-18.0 mg (potency)/kg in 3 divided portions. Clinical efficacy rates in 428 children of the 5% granule group and in 159 of the 10% granule group from whom causative bacteria were isolated, were 94.9% and 96.2%, respectively. The clinical efficacy rates for patients who were responsive to previous antibiotic therapy were 91.2% in the 5% granule group and 100% in the 10% granule group. Bacteriological eradication rate was 82.1% for 491 strains in the 5% granule group, and was 84.0% for 175 strains in the 10% granule group. The incidences of side effects were 3.9% (24/608) in the 5% fine granule group and 5.8% (12/206) in the 10% granule group. All of the side effects were slight gastrointestinal disorders, and no serious side effects were found. As for clinical laboratory test results, slight elevations of eosinophile, platelet or transaminase were observed. Based on the above results, it is considered that the appropriate dose levels of CFDN for pediatric infections ranged from 9.0 to 18.0 mg (potency)/kg a day, divided into 3 portions.

Spermine uptake by rat intestinal brush-border membrane vesicles

The uptake of spermine by isolated rat intestinal brush-border membrane vesicles was studied. Uptake was biphasic, with an initial rapid uptake followed by a prolonged slower phase. Spermine uptake was not affected by a Na+ electrochemical gradient. The equilibrium uptake of spermine was considerably dependent upon the medium pH. At pH 7.5 the degree of uptake was higher than that at pH 6.5 and was inversely proportional to the extravesicular osmolarity with a relatively high binding, which was estimated by extraporation to infinite extravesicular osmolarity (zero intravesicular space), while the uptake at pH 6.5 was not altered under the various medium osmolarities. A kinetic analysis of the initial uptake rate of spermine at 37 degrees C gave a Km of 24.2 microM and Vmax of 206.1 pmol/mg protein per min. Furthermore, the uptake at 4 degrees C was nonlinear, providing evidence for saturability. These findings suggest that spermine was associated with intestinal brush-border membrane vesicles in two ways, by binding to the outside and inside of membrane vesicles. The interaction of spermine and the apical membrane can be a contributory factor in the accumulation of this polyamine in the intestine of the intact animal.

A simple method for the simulation of unbound serum disopyramide concentration in patients

There were remarkable differences in the serum total and unbound concentrations of disopyramide (DP) and mono-N-dealkyldisopyramide (MND), the major metabolite of DP, among patients with arrhythmias. Serum levels of alpha 1-acid glycoprotein (AAG) also varied among the same patients. To predict the unbound DP concentrations, we have obtained the serum concentration-time curves of unbound DP in these patients by means of total DP concentration, DP pharmacokinetic parameters, AAG levels and dissociation constants of DP and MND at specific AAG binding sites. In patients with normal AAG levels, the theoretical values of unbound DP were in good agreement with the measured concentrations. On the other hand, in patients with high AAG levels, the theoretical values could be obtained by correcting the calculated values using both AAG levels of each patient and the equation correlating the unbound DP fraction to AAG concentrations. These findings indicate that patient AAG levels can provide valuable information permitting the rapid estimation of unbound DP concentrations, the pharmacologically active fraction, and the development of effective DP dosage regimens.

Improvement of dissolution and bioavailability for mebendazole, an agent for human echinococcosis, by preparing solid dispersion with polyethylene glycol

The solid dispersion of mebendazole was prepared with polyethylene glycol (PEG) to enhance the dissolution rate of mebendazole, an agent for the chemotherapy of human echinococcosis. The dissolution rate of the solid dispersion increased compared with the physical mixture, and also increased with the incorporation of an increasing amount of PEG-6000. An extensive improvement of the dissolution rate was observed when the ratio of the solid dispersion of mebendazole to PEG-6000 was more than 1: 2. Furthermore, greater bioavailability in rabbits was obtained after oral administration of the solid dispersion compared with the physical mixture.

H+ coupled transport of orally active cephalosporins lacking an alpha-amino group across brush-border membrane vesicles from rat small intestine

The effect of an inwardly directed H+ gradient' on the transport characteristics of ceftibuten, cefixime and analogues of ceftibuten in rat intestinal brush-border membrane vesicles have been investigated. In the presence of a transmembrane H+ gradient, ceftibuten and its analogues exhibited a peak to equilibrium overshoot and an accumulation in the vesicles against the concentration gradient. However, the uptake of cefixime and S-1006 [(6R, 7R)-(7-[(Z)-2-(2-aminothiazol-4-yl)-2-pentenoylamino]-8-oxo- 3- carbamoyloxy-methyl-5-thia-1-azabicyclo[4,2,0]oct-2-ene-2-carboxyl ic acid), which lacks a carboxyl group at position 4 of carboxyethylidene structure, exhibited no overshoot, although the equilibrium uptake was increased by a H+ gradient. The equilibrium uptake was dependent on the pH of the final incubation medium and the H+ gradient. These data suggested that the orally active cephalosporins were transported into rat intestinal brush-border membrane by the transmembrane H+ gradient and the pH of the medium.

Antithrombotic effects of KP-10614, a novel and stable prostacyclin (PGI2) analog

A chemically stable prostacyclin analog, KP-10614 [(4z,16s)-4,5,18,18,19,19-hexadehydro-16,20-dimethyl-delta 6(9;alpha)-9(o)- methano-PGI1], has been compared with two other prostacyclin derivatives (Iloprost and TEI-7165) and one prostaglandin E1 derivative (OP-1206) with respect to ADP-induced in vitro aggregation of human platelets and ex vivo platelet aggregation in rats and dogs, given by bolus injection and i.v. infusion. These compounds were also tested on the systemic arterial blood pressure of rats and dogs. KP-10614 was the most potent inhibitor of in vitro platelet aggregation induced by ADP with IC50 of 1 nM among the compounds studied in this report, and it also showed ex vivo effectiveness at doses much lower than the other three compounds. KP-10614 was also orally active. At oral doses of 25, 50 and 100 micrograms/kg, this new compound caused a dose-dependent inhibition of ex vivo platelet aggregation in rats, whereas the other three compounds were effective only at 500 micrograms/kg or more. In addition, KP-10614 showed definite antithrombotic effects at a dose range of 0.1 to 1 microgram/kg i.v. in various thrombosis models in which platelet aggregation was mainly involved. These results indicate that KP-10614 possesses therapeutic potential in thrombotic diseases.

[Intestinal absorption and urinary excretion of triethylenetetramine for Wilson's disease in rat]

Triethylenetetramine.2.HCl (trientine, TE) is an orphan drug for the treatment of Wilson's disease. There has been no reports regarding the absorption, distribution, metabolism, and excretion in the body. In the current study, the absorption and excretion of TE in rats were examined. The observed mean percentage amount of TE absorbed at the jejunum and ileum with the loop method for 1 h was 42.0% and 22.5%, respectively. Tight junction blocking agent inhibited the absorption of TE from the jejunum loop with 27%, but the absorption of TE from the ileum loop was not affected by this blocking agent. Therefore, the main absorption route for TE might be permeation across the plasma membrane of intestinal epithelial cells. TE and amikacin, a polycationic compound like TE, bound to the brush border membrane (BBM) of rat small intestine in the absence of inorganic ions such as Na+, K+, Ca2+, Mg2+ and Cu2+. But the binding of TE to BBM was inhibited markedly under the physiological concentration of these ions. The bioavailability of TE was below 10% and the plasma levels of TE in non-fasted rats were significantly lower than that observed in fasted rats. The urinary excretion of unchanged TE during 24 h was only 3.5% of the orally administered dose. However, the urinary excretion of total TE including metabolites, though they have not been identified, was 35.7%. These results suggest that low bioavailability of TE might be due to the rapid metabolism in the body after absorption from the gastrointestinal tract.

Mechanism of nasal absorption of drugs. IV: Plasma levels of radioactivity following intranasal administration of [3H]leucine enkephalin

To study the factors influencing nasal absorption of a model pentapeptide, plasma levels of total radioactivity were determined following the administration of [3H]tyr-leucine enkephalin to rats intravenously, intranasally alone, and intranasally in the presence of puromycin. The major pathway for transport of radioactivity into the blood from the nasal cavity appeared to be hydrolysis of [3H]tyr-leucine enkephalin to [3H]L-tyrosine, followed by absorption of [3H]L-tyrosine. When puromycin was added to the nasal solution in concentrations at which the in vitro hydrolysis of leucine enkephalin was completely inhibited, the appearance of radioactivity in the plasma was slowed, but plasma concentrations of radioactivity eventually reached levels comparable to those observed in the absence of puromycin. In view of the inhibitory effect of puromycin on the hydrolysis of leucine enkephalin, it was assumed that a significant fraction of the [3H]tyr-leucine enkephalin was absorbed intact in the presence of this substance. However, an assay method for intact leucine enkephalin in plasma is needed to confirm these preliminary observations.

Mechanism of nasal absorption of drugs. III: Nasal absorption of leucine enkephalin

The nasal absorption of a model peptide, leucine enkephalin (LE), was studied in rats using an in situ technique in which 4 mL of perfusion solution was circulated. Leucine enkephalin (LE) was found to undergo hydrolysis to its major metabolite des-tyrosine leucine enkephalin (DTLE). The addition of 1% sodium glycocholate (SGC) to the perfusion solution resulted in an increase in the overall rate of disappearance of LE and a decrease in the rate of formation of DTLE. When LE was added to nasal washings (i.e., Ringer's buffer that was precirculated through the nasal cavity to extract enzymes), LE was found to form DTLE. When SGC or puromycin was added to the nasal washings prior to the addition of LE, the rate of conversion of LE to DTLE was significantly reduced, suggesting that these two agents can inhibit peptidase enzyme activity in the nasal cavity. Since the volume of the solution has been shown to influence the kinetics of absorption of drugs administered nasally, a new experimental technique, the in vivo-in situ technique, which utilizes small volumes of solution and simulates realistic use of nose drops, was employed to further examine the mechanism of absorption and hydrolysis of LE in rats. Leucine enkephalin (LE) dissolved in 100 microL of Ringer's buffer was placed in the isolated nasal cavities of rats. The disappearance of LE and the appearance of DTLE were followed by rinsing the nasal cavity with fresh buffer. Disappearance of LE was always accompanied by appearance of DTLE, and the fraction of LE converted to DTLE decreased as the concentration of LE increased, suggesting a saturable enzymatic process.(ABSTRACT TRUNCATED AT 250 WORDS)

Parathyroid hormone and the vascular response to norepinephrine

Norepinephrine blood pressure reactivity is reduced in uremia, an effect attributed to excess parathyroid hormone (PTH). Most, but not all, animal and human studies support the theory that high PTH levels diminish the pressor response to norepinephrine. In hemodialysis patients in whom norepinephrine infusion tests were performed to determine the effect of parathyroidectomy on vascular responsiveness, the vascular response to norepinephrine (100 ng/kg/min) improved significantly (11.3 +/- 1.3 mm Hg before and 17.5 +/- 2.4 mm Hg after parathyroidectomy; P less than .01). Excess parathyroid hormone appears to play an active role in reduced vascular responsiveness to norepinephrine, although the mechanisms of this effect are unknown.

[Clinical and pharmacokinetic evaluation of cefdinir in children]

Thirty children were treated with cefdinir (CFDN) for the evaluation of its clinical efficacy and side effects. Their ages ranged from 1 to 9 years. The dosage of CFDN ranged from 8.1 to 15.9 mg/kg/day with the treatment continued for 2 to 10 days. Twenty-eight of the 30 patients were evaluated for clinical efficacy; 10 patients with tonsillitis, 3 with scarlet fever, 4 with lower respiratory infections, 2 with otitis media, 2 with cervical lymphadenitis, 3 with urinary tract infections and 4 with skin and soft tissue infections. The remaining 2 patients who had viral diseases were included in the evaluation for side effects. Clinical responses were excellent in 14 patients, good in 12, fair in 1 and poor in 1 with an efficacy rate of 92.9%. Diarrhea was noted in one of the 30 patients. A pharmacokinetic study on CFDN was performed in 8 fasting patients whose ages ranged from 3 to 7 years. Serum concentrations of CFDN peaked at 0.59 to 1.76 micrograms/ml (mean 1.13 microgram/ml) at 2 hours after dosing of 3 mg/kg in 4 patients, and 0.89 to 2.49 micrograms/ml (mean 1.49 micrograms/ml) 2 or 3 hours after dosing of 6 mg/kg in the other 4 patients. The 8-hour urinary excretion rates were 16.0% to 21.3% (mean 17.4%) in 4 patients given a dose of 3 mg/kg and 10.9 to 21.1% (mean 15.5%) in 4 patients given a dose of 6 mg/kg.

Synthesis of a new chemically stable prostacyclin analogue with high and long-lasting activity

The chemically stable prostacyclin analogue (Z)-4,5-didehydroisocarbacyclin analogue (6) has been synthesized. Compound 6 given intravenously or orally is very potent in inhibiting platelet aggregation.

Hemodynamic and volume changes by recombinant human erythropoietin (rHuEPO) in the treatment of anemic hemodialysis patients

Hemodynamic and volume changes induced by recombinant human erythropoietin (rHuEPO) treatment were investigated in 12 chronic hemodialysis patients with refractory anemia. After rHuEPO administration for 49 to 151 days, hematocrit (Ht) significantly improved from 19.4 +/- 2.3 to 30.1 +/- 1.1% (Mean +/- SD). Mean blood pressure (MBP) increased slightly but significantly from 78.8 +/- 13.2 to 88.9 +/- 16.9 mmHg. Hemodynamically, total peripheral resistance index (TPRI) increased significantly from 1,444 +/- 367 to 2,146 +/- 470 dynes.sec.cm-5.m2, while cardiac index (CI) decreased significantly from 4.49 +/- 0.85 to 3.37 +/- 0.60 l/min/m2. Both pulse rate (PR) and stroke volume index (SVI) also decreased significantly, but blood volume (BV) remained unchanged. Plasma renin activity and plasma norepinephrine decreased significantly. There were positive correlations between the change of MBP and that of CI, and between the change in CI and that of BV, respectively (p less than 0.05 or less). In conclusion the improvement of anemia using rHuEPO is hemodynamically associated with an increase in TPRI and a decrease in CI as well. Blood pressure elevation seems to be caused by an inappropriately minor reduction of CI. The contribution of humoral factors is not suggested.