Nephrotoxic potential of cis-diamminedichloroplatinum and four analogs in male Fischer 344 rats.

Cis-diamminedichloroplatinum [cis-DDP; NSC-119875] and four analogs (NSC-241240, NSC-271674, NSC-263158, and NSC-268252) were evaluated for their acute nephrotoxic potential in male F344 rats following iv administration. Indices of nephrotoxicity included blood urea nitrogen, serum creatinine, kidney weights, and microscopic examination. Results indicated that renal function, organ weights, and histology are important criteria for assessing the nephrotoxic potential of cis-DDP analogs, although alterations in these parameters may have been influenced by severe body weight loss. cis-DDP appeared to be the most nephrotoxic compound studied, and NSC-241240 demonstrated minimal renal damage. Ranking of compounds in order of their nephrotoxic potential (most to least) was cis-DDP, NSC-263158, NSC-268252, NSC-271674, and NSC-241240.

Effect of metabolic acidosis on phosphate transport by the renal brush-border membrane.

Metabolic acidosis produces a phosphaturia which is independent of parathyroid hormone or dietary phosphorus intake. To study the underlying mechanism, inorganic phosphate (Pi) and glucose transport were studied in brush-border membrane vesicles prepared from the renal cortex of parathyroidectomized rats gavaged for three days with either 7.5 ml of 1.6% NaCl (control) or 1.5% NH4Cl (acidosis). At killing, blood pH and plasma bicarbonate were 7.36 +/- 0.01 and 21.8 +/- 0.8 mequiv./l, respectively, in control and 7.12 +/- 0.03 (P less than 0.01) and 11.1 +/- 1.2 (P less than 0.01) in acidotic rats. Serum Pi was similar in both groups, while 24 h urine Pi excretion was higher in the acidotic group (P less than 0.01). Peak sodium-dependent uptake of Pi, measured after 1.5 min of incubation, was higher in controls than acidotic rats (4442 +/- 464 vs. 2412 +/- 259 pmol/mg protein, P less than 0.01), whereas peak glucose uptake at 1.5 min was not significantly different between the groups. Equilibrium values for Pi and glucose uptake were similar in the two groups. Km for Pi uptake in the control and acidotic animals were not different, 0.036 and 0.040 mM, respectively. By contrast, Vmax was higher in controls than in the acidotic group, 3.13 vs. 1.15 nmol/mg protein per 15 s. These results suggest that metabolic acidosis directly inhibits Pi uptake by the brush border of the proximal tubule by decreasing the availability of Pi carriers of the renal brush-border membrane.

Feasibility of improved blood glucose control in patients with insulin-dependent diabetes mellitus.

An attempt was made to improve the control of blood glucose in patients with insulin-dependent diabetes mellitus. Ten patients were studied over a period exceeding 8 mo in the outpatient department. Each patient was taught to monitor his or her own blood glucose concentration and was enrolled in an exercise program. In addition, they were taught to calibrate insulin, food, and exercise in terms of the response of the blood glucose. After 3 mo of study, there was a significant decrease in hemoglobin A1c (Hb A1c) values from a mean concentration of 10.3 to 7.6%. Hb A1c values correlated well with mean blood glucose levels (r = 0.86). Dietary analysis revealed that the patients selected a diet consisting of 25% protein, 44% fat, and 31% carbohydrate, but there was a wide range in caloric distribution. There was no correlation between blood glucose control as measured by Hb A1c and caloric distribution. Systolic blood pressures decreased greater than 10 mm Hg. Serum alkaline phosphatase also decreased in each patient as control of blood glucose improved. Three of the patients with abnormalities of nerve conduction measurement at the beginning of the study had a complete return to normal at 8 mo. An outpatient program such as this may be cost effective through the avoidance of diabetes-related hospitalizations and may provide a mechanism whereby larger studies can be designed to define further the relationship of glycemia to the sequelae of diabetes.

Renal adaptation to phosphorus deprivation: characterization of early events.

Renal adaptation to low dietary phosphorus (P) can occur within 4 h. To characterize events preceding adaptation, rats were gavaged with 0.6% P (+P) or 0.03% P (-P) diet and killed 1, 2, or 4 h later. Brush border membrane vesicles were prepared and Na-dependent phosphate (Pi), glucose, and 1-proline transport were measured. In intact rats, 1 h after gavage, serum P in +P was 8.0 +/- 0.5 and in -P, 6.1 +/- 0.4 mg/dl, p less than 0.01. One and 2 h after gavage, Pi uptake was similar between groups; at 4 h, 0.25 min Pi uptake was increased by 59.3% +/- 14.8 in -P, p less than 0.02, n = 11. In thyroparathyroidectomized rats, Pi uptake increased in -P by 40.1% +/- 7.4 compared to +P at 2.5 h after gavage, and by 51.3 +/- 9.3 at 4 h, p less than 0.025, n = 11. When actinomycin D or cycloheximide were administered both 16 h prior to and at gavage, 0.25 min Pi uptake 4 h after gavage was 59.1% +/- 14 and 60.6% +/- 19 higher in -P than +P, respectively, p less than 0.025. The adaptation was detected only when measured with an inward-directed Na-gradient. Na-dependent glucose and proline uptakes were not changed by -P diet. These studies demonstrate that early renal adaptation to low dietary P is preceded by a fall in serum P, is independent of parathyroid hormone, and does not require protein synthesis. Early adaptation may represent an increased rate of carrier movement or a change in availability of already synthesized carrier. The signal for adaptation may be the decrease in serum P, or filtered load of phosphorus.

Effect of calcium citrate supplementation on urinary calcium oxalate saturation in female stone formers: implications for prevention of osteoporosis.

In 14 women aged 37-68 y with a history of renal calcium calculi, bone densities were 12.0% below those of age-matched control subjects at the L2-4 lumbar spine (P = 0.007) and 6.4% less at the femoral neck (P = 0.095). A low-oxalate diet was supplemented with 1 g Ca/d as citrate. In 6 mo, plasma 1,25(OH)2D concentrations fell from 53.2 +/- 18.8 to 41.9 +/- 15.2 ng/L (P = 0.02) and parathyroid hormone from 39.1 +/- 17.0 to 30.8 +/- 12.5 ng/L (P = 0.02). Calcium oxalate saturation was 2.15 +/- 1.38 at baseline, 2.27 +/- 1.00 at 1 mo, and 2.06 +/- 1.57 at 6 mo. The increase in urinary calcium at 1 mo from 4.411 +/- 1.87 to 6.514 +/- 2.82 mmol/24 h (P = 0.01) was offset by a parallel increase in citrate excretion from 2.909 +/- 1.45 to 3.455 +/- 1.34 mmol/24 h (P = 0.03). Calcium citrate supplementation did not increase the lithogenicity of the women in this protocol.

A national survey of attitudes and practices of primary-care physicians relating to nutrition: strategies for enhancing the use of clinical nutrition in medical practice.

A nationwide mail survey was used to determine the degree to which primary-care physicians indicated that they practice the "core competencies" in clinical nutrition identified by Young et al (Am J Clin Nutr 1983;38:800-10). We also surveyed the nutrition-related attitudes of these physicians. Although the 3416 physicians who responded to the survey tended to report favorable attitudes toward using nutrition in their practice, these favorable attitudes were not consistent with their own reports of clinical performance. Neither the positive- or negative-attitude score correlated highly with the reported behavior-practice score. The clinical practices reported by those surveyed are well below the minimum level defined by the Young et al essential core competencies in clinical nutrition. The attitudes, practices, and demographic characteristics associated with the clinical performance variables suggest educational strategies for improving the competence of primary-care physicians and medical students in clinical nutrition.

Intermittent doxercalciferol (1alpha-hydroxyvitamin D(2)) therapy for secondary hyperparathyroidism.

Hypercalcemia and hyperphosphatemia frequently necessitate vitamin D withdrawal in hemodialysis patients with secondary hyperparathyroidism. In short-term trials, doxercalciferol (1alpha-hydroxyvitamin D(2) [1alphaD(2)]) suppressed intact parathyroid hormone (iPTH) effectively with minimal increases in serum calcium and phosphorus (P) levels. This modified, double-blinded, controlled trial examined the efficacy and safety of 1alphaD(2) use in 138 hemodialysis patients with moderate to severe secondary hyperparathyroidism by using novel dose titration; 99 patients completed the study. Hemodialysis patients with secondary hyperparathyroidism were enrolled onto this study, consisting of washout (8 weeks), open-label 1alphaD(2) treatment (16 weeks), and randomized, double-blinded treatment with 1alphaD(2) or placebo (8 weeks). Oral 1alphaD(2) was administered at each hemodialysis session, with doses titrated to achieve target iPTH levels of 150 to 300 pg/mL. Baseline iPTH levels (897 +/- 52 [SE] pg/mL) decreased by 20% +/- 3.4% by week 1 (P: < 0.001) and by 55% +/- 2.9% at week 16; iPTH levels returned to baseline during placebo treatment but remained suppressed with 1alphaD(2) treatment. In 80% of the patients, iPTH level decreased by 70%, reaching the target level in 83% of the patients. Grouping patients by entry iPTH level (<600, 600 to 1,200, and >1,200 pg/mL) showed rapid iPTH suppression in the group with the lowest level; greater doses and longer treatment were required in the group with the highest level. During open-label treatment, serum calcium and P levels were 9.2 +/- 0.84 (SD) to 9.7 +/- 1.05 mg/dL and 5.4 +/- 1.10 to 5.9 +/- 1.55 mg/dL, respectively. During double-blinded treatment, serum calcium levels were slightly greater with 1alphaD(2) than placebo, but P levels did not differ. During double-blinded treatment, 3.26% and 0.46% of serum calcium measurements exceeded 11.2 mg/dL with 1alphaD(2) and placebo, respectively (P: < 0.01); median level was 11.6 mg/dL during hypercalcemia. Intermittent oral 1alphaD(2) therapy effectively suppresses iPTH in hemodialysis patients with secondary hyperparathyroidism, with acceptable mild hypercalcemia and hyperphosphatemia.

Efficacy and side effects of intermittent intravenous and oral doxercalciferol (1alpha-hydroxyvitamin D(2)) in dialysis patients with secondary hyperparathyroidism: a sequential comparison.

Most reports on the effectiveness and side effects of oral versus parenteral calcitriol or alfacalcidol in hemodialysis patients with secondary hyperparathyroidism show no advantage of parenteral treatment. The efficacy and safety of intravenous doxercalciferol (1alphaD(2)) were studied in hemodialysis patients with secondary hyperparathyroidism (plasma intact parathyroid hormone [iPTH]: range, 266 to 3,644 pg/mL; median, 707 pg/mL). These results were compared with those of a previous trial using intermittent oral 1alphaD(2); the same 70 patients were entered onto both trials, and 64 patients completed both trials per protocol. Twelve weeks of open-label treatment in both trials were preceded by identical 8-week washout periods. Degrees of iPTH suppression from baseline were similar in the two trials, with iPTH level reductions less than 50% in 89% and 78% of patients during oral and intravenous treatment, respectively. Grouping patients according to entry iPTH levels (<750 and >/=750 pg/mL) showed similar but more rapid iPTH suppression in the low-iPTH groups, whereas longer treatment and larger doses were required by the high-iPTH groups. Highest serum calcium levels averaged 9.82 +/- 0.14 and 9.67 +/- 0.11 mg/dL during oral and intravenous 1alphaD(2) treatment, respectively (P: = not significant [NS]). Prevalences of serum calcium levels greater than 11.2 mg/dL during oral and intravenous treatment were 3.62% and 0.86% of calcium measurements, respectively (P: < 0.001). Highest serum phosphorus levels during oral and intravenous treatment averaged 5.82 +/- 0.21 and 5.60 +/- 0.21 mg/dL, respectively (P: = NS). The percentage of increments in serum phosphorus levels during oral treatment exceeded that during intravenous treatment during 5 of 12 treatment weeks. Thus, intermittent oral and intravenous therapy with 1alphaD(2) reduced iPTH levels effectively and similarly, hypercalcemia was less frequent, and serum phosphorus levels increased less during intravenous than oral 1alphaD(2) therapy, suggesting that intravenous 1alphaD(2) therapy may be advantageous in patients prone to hypercalcemia or hyperphosphatemia.

Dose-response characteristics of mibefradil, a novel calcium antagonist, in the treatment of essential hypertension.

The aim of this study was to determine the dose-response characteristics of the calcium antagonist, mibefradil, and to evaluate its antihypertensive efficacy and safety in varying doses in patients with mild-to-moderate hypertension. Three hundred and three eligible patients were randomized to receive once-daily 6.25-, 12.5-, 25-, 50-, 100-, 150-, or 200-mg mibefradil doses or placebo for 4 weeks. Repeated blood pressure measurements and electrocardiographic recordings were obtained for the 24 h following the last dose of the placebo run-in period and for the first and last doses of randomized treatment. A statistically significant (P < .001 versus placebo) and clinically relevant drop in sitting diastolic blood pressure (SDBP) both at trough and at peak was observed in the 50-, 100-, 150-, and 200-mg mibefradil dose groups (trough placebo-corrected reductions: -4.9, -9.1, -9.9, and -11.9 mm Hg, respectively), with a significant dose-response relationship (P < .001) and high response rates. Trough/peak ratios for the placebo-corrected change from baseline to week 4 in SDBP were >85% for the 50- and 100-mg doses and 68% and 69% for the 150- and 200-mg doses, respectively. The full antihypertensive effect of mibefradil was achieved within 1 week of treatment. Reductions in sitting systolic blood pressure (SSBP) closely paralleled those in SDBP. The antihypertensive effect of mibefradil was associated with a slight dose-dependent decrease in heart rate and increase in the pulse rate (PR) electrocardiographic interval [corrected]. The appropriate therapeutic dose range of mibefradil in the management of mild-to-moderate essential hypertension is 50 to 100 mg.

Fatal neurotoxicity of arteether and artemether.

Artemisinin (qinghaosu) and several derivatives have been developed and are in use as antimalarial drugs but scant information is available regarding animal or human toxicity. Following a eight-day, multiple-dose, pharmacokinetic study of arteether (AE) (10 mg/kg/day [n = 6] and 20 mg/kg/day [n = 6]) in dogs, all high-dose animals displayed a progressive syndrome of clinical neurologic defects with progressive cardiorespiratory collapse and death in five of six animals. Neurologic findings included gait disturbances, loss of spinal and pain response reflexes, and prominent loss of brain stem and eye reflexes. Animals had prolongation of QT interval corrected for rate (QTc) on electrocardiograms (ECGs) with bizarre ST-T segment changes. Prominent neuropathic lesions were noted to be primarily limited to the pons and medulla. Similar lesions with dose-related severity were noted in eight other dogs studied in a second study with intramuscular (IM) administration of AE in sesame oil during a 28-day, dose-ranging study using 5, 10, 15, and 20 mg/kg/day. Injury, graded by a pathologist blinded to the dose group, showed a dose-related, region-specific injury in all animals that was most pronounced in the pons. Further studies in Sprague-Dawley rats using IM administration of AE and artemether (AM) at a dose of 12.5-50 mg/kg/day for 28 days confirmed the onset of a clinical neurologic syndrome with dose-related changes in body weight, activity, and seizure-like activity, stereotypic movement disorders, and ECG changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative analysis of ES-285, an investigational marine anticancer drug, in human, mouse, rat, and dog plasma using coupled liquid chromatography and tandem mass spectrometry.

A method was developed for the quantitative analysis of the novel anticancer agent ES-285 (spisulosine; free base) in human, mouse, rat, and dog plasma using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry in order to support pre-clinical and clinical studies with the drug. Sample preparation was carried out by protein precipitation with acetonitrile, containing isotopically labeled (d(3)) ES-285 as internal standard. Aliquots of 10 micro l of the supernatant were injected directly on to an Inertsil ODS-3 column (50 x 2.0 mm i.d., 5 micro m). Elution was carried out using methanol-10 mM ammonium formate (pH 4) in water (80 : 20, v/v) pumped at a flow-rate of 0.2 ml min(-1) with a run time of 8 min. Multiple reaction monitoring chromatograms obtained on an API365 triple-quadrupole mass spectrometer were used for quantification. The lower limit of quantitation (LLOQ) was 10 ng ml(-1) in human, mouse, rat, and dog plasma and the linear dynamic range extended to 500 ng ml(-1). A full validation of the method was performed in human plasma, and partial validations were performed in mouse, rat and dog plasma. Accuracies and precisions were <20% at the LLOQ concentration and <15% for all other concentrations in all matrices. ES-285 was stable during all steps of the assay. Thus far this method has been used successfully to analyze over 500 samples in pre-clinical trials, and will be implemented in the planned clinical phase I studies.

Developmental toxicity studies of 2-(difluoromethyl)-dl-ornithine (DFMO) in rats and rabbits.

DFMO, an irreversible inhibitor of ornithine decarboxylase (ODC), is under development as a chemopreventive drug against cancers with pronounced proliferative phases. In support of human clinical trials, preclinical developmental toxicity studies were conducted in pregnant rats and rabbits. Rats were treated during GD 6-17, and fetuses were obtained by C-section on GD 20. Rabbits were treated during GD 7-20, and fetuses were obtained by C-section on GD 29. The dose range-finding study in rats (5/group at 0, 50, 125, 300, 800, or 1000 mg/kg/day) revealed maternal toxicity at doses > or = 800 mg/kg/day (decreased body weights and food consumption) and developmental toxicity at doses > or = 300 mg/kg/day (increased early resorptions and reduced fetal body weights). In the main study, rats (25/group) received 0, 30, 80, or 200 mg/kg/day. Developmental toxicity in the absence of maternal toxicity was observed at 200 mg/kg/day as significantly decreased fetal weights and increased incidence of litters with skeletal variations of 14th rudimentary rib, 14th full rib, and/or 27th presacral vertebrae. There were no treatment-related fetal skeletal malformations or external or visceral anomalies at any dose level. The dose range-finding study in rabbits (5/group at 0, 30, 60, 120, 240, or 500 mg/kg/day) revealed developmental toxicity at doses > or = 60 mg/kg/day (increased resorptions and reduced fetal body weights) in the absence of maternal toxicity. In the main study, rabbits (20/group) received 0, 15, 45, or 135 mg/kg/day. Developmental toxicity in the absence of maternal toxicity was observed at 135 mg/kg/day as nonsignificantly increased early resorptions, decreased implantation sites, decreased viable fetuses, and reduced fetal weights. There were no external, visceral, or skeletal anomalies at any dose level. Thus, in the main developmental toxicity studies, DFMO produced developmental but not maternal toxicity at 200 and 135 mg/kg/day in rats and rabbits, respectively. Accordingly, in rats, the maternal no-observable-effect level (NOEL) was 200 mg/kg/day and the fetal NOEL was 80 mg/kg/day; while in rabbits the maternal NOEL was 135 mg/kg/day and the fetal NOEL was 45 mg/kg/day. These fetal NOELs are several-fold higher than the dose level currently used in Phase II and III clinical trials (approximately 13 mg/kg).

Thirteen-week oral toxicity study of difluoromethylornithine in combination with tamoxifen citrate in female dogs.

PURPOSE: Cancer chemoprevention is the use of pharmacologic or natural agents to inhibit the development of cancer. Difluoromethylornithine (DFMO) is an irreversible inhibitor of ornithine decarboxylase, the rate-limiting enzyme in the biosynthesis of polyamines. DFMO has demonstrated chemopreventive efficacy in animal models of tumorigenesis. Tamoxifen (TAM), a nonsteroidal antiestrogen, is approved for use in the treatment of estrogen receptor-positive breast carcinoma and has demonstrated efficacy in chemoprevention of breast cancer in women at high risk for the disease. The administration of TAM with DFMO is being considered for development by the National Cancer Institute as a potential drug regimen for the chemoprevention of breast carcinoma. METHODS: The toxicity of DFMO in combination with TAM was evaluated in female Beagle dogs following 13 weeks of daily oral administration by capsule. Dose levels in milligrams per kilogram body weight per day were: 0 (vehicle control), 100 DFMO, 0.1 TAM, 1.0 TAM, 0.1 TAM + 100 DFMO and 1.0 TAM + 100 DFMO. RESULTS: No mortalities occurred. Diarrhea was produced by TAM and vaginal discharge, due to reproductive tract lesions, was produced by both DFMO and TAM, either alone or in combination. DFMO decreased reticulocyte counts and TAM increased counts of mature neutrophils. DFMO alone resulted in lesions to the intestines and ovaries, and cornified epithelium of vagina and cervix. TAM produced cornified epithelium of vagina and cervix, and numerous lesions in the ovaries, fallopian tube, uterus, cervix and vagina which were likely due to an estrogen agonist effect. Coadministration of DFMO increased the incidence and/or severity of these reproductive tract lesions. Each compound alone produced ovarian atrophy, and antral follicles and corpora lutea were completely absent in the 1.0 TAM + 100 DFMO group. CONCLUSIONS: Coadministration of DFMO and TAM resulted in additive toxicity involving the female reproductive system.

Difluoromethylornithine in combination with tamoxifen in female rats: 13-week oral toxicity study.

PURPOSE: Cancer chemoprevention is the use of pharmacologic or natural agents to inhibit the development of cancer. Difluoromethylornithine (DFMO) is an irreversible inhibitor of ornithine decarboxylase, the rate-limiting enzyme in the biosynthesis of polyamines. DFMO has demonstrated chemopreventive efficacy in animal models of tumorigenesis. Tamoxifen (TAM) is currently used for treatment of estrogen receptor-positive breast carcinoma and has demonstrated efficacy in chemoprevention of breast cancer in women at high risk for the disease. The administration of tamoxifen with DFMO is being considered for development by the National Cancer Institute as a potential drug regimen for the chemoprevention of breast carcinoma. METHODS: The toxicity of DFMO in combination with TAM was evaluated in female rats following 13 weeks of daily administration by gavage. Dose groups were vehicle control, DFMO (1000 mg/kg per day), low TAM (0.25 mg/kg per day), high TAM (2.5 mg/kg per day), low combination (1000 + 0.25) and high combination (1000 + 2.5). RESULTS: No mortalities occurred in the study. Clinical signs of toxicity were limited to dermal lesions consisting of scab formation and abrasions produced by DFMO. Administration of either DFMO or TAM resulted in decreased body weight gains, with coadministration having an additive effect. Serum albumin, total protein, cholesterol and triglyceride levels were decreased in all drug-treated dose groups, although histologic evidence of liver lesions were not seen. TAM resulted in increased numbers of red blood cells, whereas DFMO produced a slightly anemic response. DFMO produced lesions in the small intestine consisting of necrosis of crypt epithelium and crypt microabscess, which were enhanced by TAM coadministration. Administration of TAM resulted in histologic changes in the ovaries, fallopian tube, vagina, cervix and uterus, indicating that inhibition of ovulation and reproductive cycle arrest in the proestrus stage had occurred. Coadministration with DFMO did not affect the changes to the reproductive system induced by TAM. CONCLUSIONS: Coadministration of DFMO with tamoxifen did not result in toxicity unique to the combination drug regimen, but rather toxicity resulted from administration of each drug. Under the conditions of the study, the overall toxicity produced by dual administration of DFMO with tamoxifen was additive with respect to the toxicity associated with each agent alone.

Genetic toxicology assessment of HI-6 dichloride.

The oxime HI-6 dichloride [1-(2 hydroxyiminomethyl -1-pyridino)-3-(4-carbamoyl-1-pyridino)-2-oxapropane dichloride monohydrate] has shown to be a potent reactivator of cholinesterase activity and may have efficacy for the treatment of organophosphate intoxication [SIPRI, 1976; Schenk et al.; Arch Toxicol 36:71-81, 1976]. As part of a preclinical safety assessment program, the genetic toxicology of HI-6 dichloride was evaluated in a series of assays designed to measure induction of gene mutations and chromosomal aberrations. HI-6 dichloride gave negative responses in the Salmonella mutagenicity assay and in the CHO/HGPRT gene mutation assay. Dose-dependent increases in the frequency of chromosomal aberrations were noted when HI-6 dichloride was tested in cultured CHO cells and in cultured human peripheral blood lymphocytes. The mouse lymphoma gene mutation assay, reputed to measure both gene mutations and chromosomal deletions, was negative in the absence of metabolic activation. Depending on the criteria employed, a negative or equivocal response was seen in the presence of rat liver-derived S-9 mix. An in vivo rat bone marrow metaphase assay performed to further investigate the in vitro clastogenic responses was negative. The results from these studies indicate that HI-6 dichloride does not induce gene mutations in vitro; however, it is clastogenic in vitro but does not appear to be clastogenic in vivo.

Neurotoxicity in animals due to arteether and artemether.

Several artemisinin (qinghaosu) derivatives have been developed and are in use as antimalarial drugs but scant animal or human toxicity data are available. We noted a progressive syndrome of clinical neurological defects with cardio-respiratory collapse and death in 5/6 dogs dosed daily for 8 d with intramuscular arteether (AE) at 20 mg/kg/d in a pharmacokinetic study. Neurological findings included gait disturbances, loss of spinal reflexes, pain response reflexes and prominent loss of brain-stem and eye reflexes. Electrocardiography showed prolongation of the QT interval corrected for rate (QTc). Prominent neuropathic lesions were sharply limited to the pons and medulla. Neurological injury, graded by a pathologist 'blinded' to dose group, showed a dose-related region-specific injury which was most pronounced in the pons and medulla in all animals. Rats treated with AE and artemether (AM) at 12.5 to 50 mg/kg/d for 28 d confirmed clinical neurological abnormalities with high doses (> 25 mg/kg/d) after 6-14 d. Neuropathological examination of rat brain sections at 5 levels from the rostral cerebrum to the caudal medulla showed a dose-related pattern of injury characterized by hyalinized neuron cell bodies and loss of Nissl substance; changes congruent with those noted in dogs. No significant difference was noted in the extent, type, or distribution of lesions in the brains of rats treated with equivalent doses of AE or AM.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of enalapril/diltiazem ER in hypertensive patients with coexisting renal dysfunction. Enalapril/Diltiazem ER in Hypertensive Renal Disease Group.

Both enalapril and long-acting diltiazem have been shown to effectively lower blood pressure (BP) in hypertensive patients. Furthermore, in clinical studies, these two agents provided beneficial renal effects in these patients when administered on a long-term basis. A combination of enalapril/diltiazem ER was evaluated in 62 patients with Stage 1-3 hypertension and coexisting renal disease. This trial used a multicenter, randomized, double-blind, parallel group design. The study consisted of a 12-week double-blind phase followed by a 6-month open-label extension phase. The combination of enalapril/diltiazem ER was shown to reduce BP following both short-term and long-term treatment phases. Patients in Renal Group I (creatinine clearance CrCl): 30-59 ml/min/1.73 m2) had decreases of -18/-16 and -25/-20 mm Hg after 12 weeks and 9 months of therapy, respectively. Those in Renal Group II (CrCl: 10-29 ml/min/1.73 m2) had similar decreases of -23/-18 and -23/-19 mm Hg at these time points. The adverse events, in both phases, were those associated with the respective monotherapies. A reduction in CrCl with a coincident decrease in proteinuria was noted for both renal groups. The combination of enalapril/diltiazem ER lowered BP and was generally well tolerated by the patients. The combination of these two agents should improve the management of hypertensive patients.

Basal and stimulated cytosolic platelet calcium in essential hypertension.

It was reported that in essential hypertension, basal platelet free cytosolic (Ca)i measured with the fluorescent dye Quin 2, is elevated, but increases normally after thrombin stimulation. These data, were interpreted to suggest that plasma membrane fluxes are altered but the release of internal Ca2+ stores is intact. Previous studies have shown that Quin 2 inhibits Ca2+ release from internal stores following thrombin (T)-stimulation. Thus, we reassessed resting and T-stimulated platelet (Ca)i using the fluorescent dyes Fura 2 or Quin 2 in 11 subjects, 5 controls and 6 hypertensives. Mean basal (Ca)i with Quin 2 in controls was 138 +/- 15 nM vs 114 +/- 11 nM in hypertensives, (NS). By contrast, in the same platelet preparation (Ca)i with Fura 2 was higher in hypertensives than controls, 217 +/- 27 nM vs 120 +/- 4 nM, P less than .05. Blood pressure was correlated to (Ca)i obtained with Fura 2, R = 0.55. Thrombin 0.5 U/ml added to platelets in Ca-free media caused a multiphasic rise in (Ca)i with Fura 2. Although the absolute rise in (Ca)i in controls (592 +/- 104 nm) vs hypertensives (512 +/- 60 nm) did not differ, the % rise was less in hypertensives. Thus, 1) in the same population a higher resting (Ca)i was detected in platelets from essential hypertensives with Fura 2, but not with Quin 2; and 2) Ca2+ release from internal stores is altered in hypertension. Thus, Fura 2 is superior to Quin 2 in evaluating platelet (Ca)i.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of indapamide 1.25 mg once daily in elderly patients with mild to moderate hypertension.

The objective of this study was to evaluate the safety and efficacy of indapamide 1.25 mg once daily as monotherapy in elderly patients (65 years and older) with mild to moderate essential hypertension. Two hundred and seventy-nine (279) elderly patients were enrolled in a washout period, during which patients received single-blind placebo for 4 weeks. Patients demonstrating supine diastolic pressures between 95 mm Hg and 114 mm Hg at the end of the 4-week placebo washout period were entered into the 8-week double-blind treatment period. Two hundred and four (204) patients qualified for the study and were randomized to the double-blind treatment; 103 patients received indapamide 1.25 mg and 101 patients received placebo for 8 weeks. Overall, 177 patients (92 indapamide and 85 placebo) completed the study. The primary efficacy criterion was the mean change in supine diastolic blood pressure (DBP) from double-blind baseline to the end of 8 weeks of therapy. By week 8 of the double-blind treatment period, indapamide 1.25 mg produced a statistically significant (P = 0.0037) decrease in supine DBP of 8.2 mm Hg compared to a decrease of 5.3 mm Hg produced in the placebo group. Additionally, indapamide 1.25 mg was statistically (P = 0.0028) more effective than placebo in reducing supine systolic BP (SBP) (-10.1 vs -4.2 mm Hg). The incidence of drug-related adverse events during the double-blind treatment period was similar between the two treatment groups. A low dose of indapamide, 1.25 mg, given once daily for 8 weeks was effective as monotherapy with respect to BP reduction in an elderly population with mild to moderate hypertension. Indapamide 1.25 mg was safe and generally well tolerated in this elderly patient population.

Reproductive and developmental toxicity studies of pyridostigmine bromide in rats.

These studies were performed to evaluate the reproductive and developmental toxicity of pyridostigmine bromide (PB) in rats. Separate male and female fertility/reproductive performance studies, a perinatal/postnatal study and a teratology study were conducted. Dose levels were sufficient to result in overt cholinergic tremors at the high dose in each study. PB did not affect male or female fertility/reproductive performance. Pups born to treated dams did show slight, transient decreases in body weight gain, apparently secondary to the nursing behavior of dams demonstrating overt tremors. PB did not result in an increase in visceral or skeletal malformations. A slight increase in delayed ossification and early resorption were seen at the highest dose tested and were considered secondary to maternal stress/toxicity.