Upgradings on the energetics of amphibia heart in vitro. Quabain and total tissue transport ATPases.
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Adenosine Diphosphate↗
Biomedical subjects
P Periti
Publications and source records attributed to P Periti.
Pharmacokinetic drug interactions of macrolides.
The macrolide antibiotics include natural members, prodrugs and semisynthetic derivatives. These drugs are indicated in a variety of infections and are often combined with other drug therapies, thus creating the potential for pharmacokinetic interactions. Macrolides can both inhibit drug metabolism in the liver by complex formation and inactivation of microsomal drug oxidising enzymes and also interfere with microorganisms of the enteric flora through their antibiotic effects. Over the past 20 years, a number of reports have incriminated macrolides as a potential source of clinically severe drug interactions. However, differences have been found between the various macrolides in this regard and not all macrolides are responsible for drug interactions. With the recent advent of many semisynthetic macrolide antibiotics it is now evident that they may be classified into 3 different groups in causing drug interactions. The first group (e.g. troleandomycin, erythromycins) are those prone to forming nitrosoalkanes and the consequent formation of inactive cytochrome P450-metabolite complexes. The second group (e.g. josamycin, flurithromycin, roxithromycin, clarithromycin, miocamycin and midecamycin) form complexes to a lesser extent and rarely produce drug interactions. The last group (e.g. spiramycin, rokitamycin, dirithromycin and azithromycin) do not inactivate cytochrome P450 and are unable to modify the pharmacokinetics of other compounds. It appears that 2 structural factors are important for a macrolide antibiotic to lead to the induction of cytochrome P450 and the formation in vivo or in vitro of an inhibitory cytochrome P450-iron-nitrosoalkane metabolite complex: the presence in the macrolide molecules of a non-hindered readily accessible N-dimethylamino group and the hydrophobic character of the drug. Troleandomycin ranks first as a potent inhibitor of microsomal liver enzymes, causing a significant decrease of the metabolism of methylprednisolone, theophylline, carbamazepine, phenazone (antipyrine) and triazolam. Troleandomycin can cause ergotism in patients receiving ergot alkaloids and cholestatic jaundice in those taking oral contraceptives. Erythromycin and its different prodrugs appear to be less potent inhibitors of drug metabolism. Case reports and controlled studies have, however, shown that erythromycins may interact with theophylline, carbamazepine, methylprednisolone, warfarin, cyclosporin, triazolam, midazolam, alfentanil, disopyramide and bromocriptine, decreasing drug clearance. The bioavailability of digoxin appears also to be increased by erythromycin in patients excreting high amounts of reduced digoxin metabolites, probably due to destruction of enteric flora responsible for the formation of these compounds. These incriminated macrolide antibiotics should not be administered concomitantly with other drugs known to be affected metabolically by them, or at the very least, combined administration should be carried out only with careful patient monitoring.(ABSTRACT TRUNCATED AT 400 WORDS)
Anti-Bacterial Agents↗
Teicoplanin--its role as systemic therapy of burn infections and as prophylaxis for orthopaedic surgery. Italian Study Groups for Antimicrobial Prophylaxis in Orthopaedic Surgery and Burns.
Two randomized studies have been initiated to establish the role of teicoplanin as systemic therapy for infections in burns patients and as short-term prophylaxis for orthopaedic implant surgery. Opportunistic micro-organisms causing infections in burn patients are often acquired in hospital. These infections commonly involve Gram-positive organisms which may be resistant to several antibiotics. Teicoplanin, alone and in combination with additional antibacterial drugs, is effective in the treatment of Gram-positive infections of various types. In addition, teicoplanin has proved useful as prophylaxis against infection in orthopaedic surgery. Deep prosthetic infections are very difficult to cure without removing the infected device; the outcome can be devastating, such as total loss of joint function, amputation, and, occasionally, death. Preliminary results from the two studies are encouraging and show that teicoplanin has a role to play both in treatment of infection and as prophylaxis against hospital-acquired infection.
Adult↗
Chromosomal characterization of methotrexate-resistant human T-lymphoblast leukemia cells (CCRF-CEM) with impaired polyglutamylation.
Two sublines of the human T-lymphoblast leukemia cell line CCRF-CEM, which were resistant to methotrexate (MTX) due to defective MTX polyglutamate synthesis, were karyologically characterized. No statistically significant differences in the modal number of chromosomes were noted in resistant cells (CCRF-CEM/P) as compared to parent cells (91, range, 86-123; and 93, range; 78-103, respectively). Fifteen marker chromosomes were identified and their origins at least partially established. An isochromosome 7q, (marker 13) was present in all MTX-resistant cells but was not found in any sensitive cell karyotype. This marker chromosome may be involved in the emergence of drug-resistant cells from the parental population of CCRF-CEM cells. In all cell lines, chromosomes 8, 9 and 14 appear to be highly unstable and are involved in the genesis of many marker chromosomes. These chromosomes are also implicated in the in vivo genesis of various leukemias and lymphomas, which suggests that both in vivo tumor progression and in vitro cellular adaptation are marked by chromosome mutations that may activate multiple oncogenes.
Cell Line↗
Systemic absorption of 3H-fenticonazole after vaginal administration of 1 gram in patients.
Fourteen women, five with normal cervicovaginal mucosa (Group 1), five with cervical carcinoma (Group 2) and four with relapsing vulvovaginal candidiasis (Group 3) were enrolled and completed this open clinical trial. Each subject received a single dose of 1.82 +/- 0.3 g on average of vaginal paste (for ovules) containing about 1000 mg of 3H-fenticonazole nitrate (266 microCi). Twelve hours after vaginal administration, the paste was removed by vaginal washing. Blood, urine and stool samples were collected at specified time intervals for five days. Plasma, urine, stools and all used material in contact with the paste were assayed for radioactivity. No measurable levels of radioactivity were detected in plasma of subjects of Groups 1 and 3 while in 4 of the 5 subjects with cervical carcinoma (Group 2) fenticonazole was detected during the 24 h after administration with a peak level at about 8 hours. For a period of 5 days, 0.4-1.5% of the dose on average was recovered from urine, and 0.18-0.32% from feces. Based on the excretion data, the extent of vaginal absorption of fenticonazole nitrate in women with vulvovaginal candidiasis was 1.81 +/- 0.57% of the dose, while in women with normal cervicovaginal mucosa it accounted for 0.58 +/- 0.28% of the administered dose. In patients with cervical carcinoma, absorption was 1.12 +/- 0.53%. The maximum amount absorbed corresponds to an exposure of about 0.4 mg/kg of fenticonazole nitrate (for a subject weighing 50 kg). Consequently, the vaginal administration of one ovule containing 1000 mg of fenticonazole nitrate seems to be devoid of risk for patients.
Absorption↗
Tissue distribution of cefotetan in patients with Crohn's disease.
Concentrations of cefotetan in the intestinal wall of patients with Crohn's disease were investigated with the method of tissue homogenates with the aim to evaluate the effects of inflammation on tissue distribution. Twenty-four patients who underwent surgery were treated with a 2-gram single dose of cefotetan intravenously before the operation. The mean tissue levels in inflamed intestinal wall were constantly higher than in normal wall, but the difference was statistically significant only in samples taken more than 2 h after cefotetan administration (31.0 +/- 17.8 vs 14.7 +/- 11.4 mg/kg; p less than 0.05). The mean residence time was 284.3 min for inflamed tissue and 123.9 min for normal. The areas under the curve were significantly higher in inflamed wall than in normal, with mean values of 4,789 and 3,020.2 mg/l.h, respectively (p less than 0.05). Inflammation seems to facilitate the penetration of cefotetan into the intestinal wall of patients with Crohn's disease but above all, it increases the mean residence time in inflamed tissue.
Adult↗
Cost-effective use of once-daily ceftriaxone: overview of a symposium.
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Ambulatory Care↗
Combination chemotherapy with cyclophosphamide, fluorouracil, and either epirubicin or mitoxantrone: a comparative randomized multicenter study in metastatic breast carcinoma.
From February 1987 to January 1989, 60 patients with advanced breast cancer and no prior chemotherapy for advanced disease were randomized and studied, with 31 treated with fluorouracil, epirubicin, and cyclophosphamide (FEC) and 29 patients with fluorouracil, mitoxantrone, and cyclophosphamide (FNC). Doses were 500 mg/m2 fluorouracil, 500 mg/m2 cyclophosphamide, and 50 mg/m2 epirubicin2 or 10 mg/m mitoxantrone, i.v. Day 1 every 3 weeks. There were no statistically significant differences in pretreatment patient characteristics between the groups. Fifty-six patients were evaluable for response (29 in the FEC arm and 27 in the FNC arm). The response rates were 48.2% for the FEC group (complete response (CR) 10.3% and partial response (PR) 37.9%) and 40.7% for the FNC group (CR 3.7% and PR 37%) (not significantly different, NS). The median response duration was 247 and 267 days, respectively (NS), the median time to progression and time to treatment failure was 244 and 155.5 days for the FEC group and 86 and 98 days for the FNC group, respectively (NS). The incidence of nausea/vomiting was 87.1% in the FEC group and 79.3% in the FNC group, with comparable severity. Alopecia occurred in 80.6% of FEC patients and 44.8% of FNC patients (p less than 0.05). The incidences and degrees of severity of leukopenia, anemia, and cardiotoxicity were comparable in the two treatment groups. Efficacy and toxicity of the two regimens were quite similar. FNC can improve the quality of life of patients by providing significantly less alopecia.
Antineoplastic Combined Chemotherapy Protocols↗
Anandron (RU 23908) in metastatic prostate cancer: preliminary results of a multicentric Italian study.
Between March 1986 and March 1987, 48 patients with stage D prostate carcinoma were entered into a multicentric pilot study using the pure nonsteroidal antiandrogen nilutamide (Anandron--RU 23908) at the dose of 100 mg t.i.d. as the only therapy until disease progression or the occurrence of toxicity. Minimum follow-up was 15 months. Median age of patients was 72 (56 to 83) and median initial Performance Status (PS) was 1 (0 to 3). Of the 48 patients, 29 were untreated, while 19 patients were progressing following treatment by orchiectomy, LHRH analogs, or other endocrine therapies. According to the National Prostatic Cancer Project (NPCP) criteria, 43 patients were evaluable for response. Overall best response in untreated patients was partial response (PR), 41.6%; stationary disease (SD), 54.1%; 73.6% of pretreated patients achieved SD. Median progression-free survival and overall survival in untreated patients were 325 and 696 days, respectively, and 174 and 447 days, respectively, in pretreated patients. The more common side effects were G.I. toxicity (65%), hemeralopia (27%), and alcohol intolerance (6.2%). Results of this study suggest that Anandron may be a safe and effective treatment for patients with advanced prostatic cancer.
Aged↗
Biochemical modulation of fluoropyrimidines by antifolates and folates in an in vitro model of human leukemia.
Although 5-fluorouracil (FUra) is one of the most effective cytotoxic agents in the treatment of various solid tumors (carcinomas of the gastro-intestinal tract, breast, head and neck), remissions occur in only 20 to 30% of cases and usually are of short duration. Recently, preclinical studies have shown that the antitumor activity of FUra can be potentiated by modulating the metabolism of this drug by using other substances, in particular antifolates of folates. Pretreatment with antifolates may, by blocking de novo purine biosynthesis and consequently increasing phosphoribosyl pyrophosphate (PRPP) pools, enhance the conversion of FUra to active fluoronucleotide pools via orotate phosphoribosyltransferase. Methotrexate (MTX) pretreatment may also enhance binding of the fluoropyrimidine inhibitor, 5-fluodeoxyuridylate (FdUMP), to the target enzyme, thymidylate synthase (TS), indirectly by increasing dihydrofolate polyglutamates or directly, as MTX polyglutamates, by enhancing the formation of ternary complexes with FdUMP and TS. Exogenous folates, in particular 5-formyltetrahydrofolate (folinate, leucovorin, LV), can, by raising the intracellular levels of 5, 10-methylenetetrahydrofolate, lead to increased formation and stabilization of the ternary complex formed by TS, the folate coenzyme, and FdUMP. In vitro studies have also shown potentiation of FUra cytotoxicity by antifolates and folates against human lymphoblastic leukemia cell lines. Thus, while FUra may have little or no single agent activity in leukemias and lymphomas, it may be converted to an active drug in these neoplasms by appropriate modulation. Clinical studies of sequential MTX-FUra or combined LV-FUra based upon experimental tumor results reviewed herein, are warranted.
Antineoplastic Combined Chemotherapy Protocols↗
Efficacy and tolerance of cefpodoxime proxetil compared with co-amoxiclav in the treatment of exacerbations of chronic bronchitis.
This European, multicentre trial evaluated the efficacy and tolerance of cefpodoxime proxetil in comparison with co-amoxiclav (amoxycillin plus clavulanic acid) in the treatment of acute exacerbations of chronic bronchitis. The study design was double-blind and double-placebo controlled. Doses of either 200 mg bd of cefpodoxime proxetil or 500 mg/125 mg tds amoxycillin plus clavulanic acid were given orally for 9.6 +/- 1.8 days. Two hundred and fifty-one patients were enrolled in 27 centres in West Germany, France, and Italy. The overall clinical efficacy was 97.2% in the cefpodoxime proxetil group compared with 94.7% in the co-amoxiclav group. Fifty-eight adverse events, mainly gastrointestinal, occurred in 42 patients with no significant difference between the groups. A significant difference in the number of resistant pathogens on pre-treatment culture to the advantage of cefpodoxime was noted. In our experience, both drugs were of similar value in the treatment of respiratory tract infections. Thus, cefpodoxime proxetil should be an effective antibiotic for the treatment of acute exacerbations of chronic bronchitis.
Adult↗
Human pharmacokinetic and pharmacodynamic profiles of leuprorelin acetate depot in prostatic cancer patients.
A total of 21 patients with advanced prostatic cancer and one patient with benign prostatic hypertrophy received 3.75, 7.5 or 15 mg leuprorelin acetate depot subcutaneously. Serum leuprorelin concentrations increased immediately after injection, reaching a peak concentration (range 13.1-54.5 ng/ml), which was directly proportional to dose, within 3 h. Mean drug levels subsequently declined to a plateau directly proportional to dose at 5 weeks. There was also a significant (P less than 0.01) dose-dependent increase in the area under the concentration-time curve for 0-35 days. Serum concentrations of luteinizing hormone and follicle stimulating hormone rose initially with all doses, followed by a rise in serum testosterone and dihydrotestosterone concentrations, which then fell sharply, within 3 weeks. A reduced level of follicle stimulating hormone subsequently occurred in all 20 evaluable patients and was maintained in 17 patients over 5 weeks. There was also marked initial suppression of luteinizing hormone levels in 15 patients and in 13 this continued. Castration levels of testosterone and dihydrotestosterone were maintained in all patients for up to 5 weeks. In two patients there was a complete response, in 14 a partial response and in three stable disease, with no significant differences in relation to dose. Clinical improvement and serum hormonal changes suggest that leuprorelin acetate depot is effective at a dose as low as 3.75 mg when given once every 4 weeks.
Aged↗
Leuprorelin acetate depot in advanced prostatic cancer: a phase II multicentre trial.
The therapeutic efficacy and safety of various doses of leuprorelin acetate depot were determined in an open, multicentre study of patients with locally advanced or metastatic prostatic cancer (stages C, D1 or D2). Patients were randomly assigned to receive 3.75 mg (30 cases), 7.5 mg (eight cases), 15 mg (eight cases) and 30 mg (one patient) leuprorelin acetate depot administered subcutaneously once every 4 weeks. Of the 43 patients evaluable, two (5%) had complete remission, 23 (53%) partial remission and 13 (30%) patients stable disease. No significant differences were observed in response rates in relation to dose, disease stage or previous hormonal therapy. Disappearance or improvement in bone pain and urinary symptoms occurred in 63% and 79% of cases, respectively. Serum androgen concentrations decreased rapidly and persistently to castration levels, without significant differences for different doses. Treatment was well tolerated with a low incidence of mild side-effects - gynaecomastia (16%), nausea/vomiting (13%) and diarrhoea (2%). It is concluded that 3.75 mg leuprorelin acetate depot given subcutaneously once every 4 weeks is able to produce hormonal effects in all patients, an overall objective response comparable to that obtained using higher doses.
Aged↗
Comparative in vitro activity of the new oxazolidinones DuP 721 and DuP 105 against staphylococci and streptococci.
The in vitro activity of DuP 721 and DuP 105, two orally active members of the oxazolidinones, was compared with that of glycopeptides and ciprofloxacin against 185 gram-positive isolates. Ninety percent of Staphylococcus aureus isolates, including penicillin- and methicillin-resistant strains, were inhibited by DuP 721 at 1 micrograms/ml and by DuP 105 at 16 micrograms/ml; DuP 721 inhibited 90% of coagulase-negative staphylococci tested at 1 micrograms/ml. The MIC90 for Streptococcus faecalis was 4 micrograms/ml with DuP 721 and 16 micrograms/ml with DuP 105; DuP 721 inhibited 90% of beta-hemolytic streptococci of group A at 0.5 micrograms/ml. Similar results on selected strains were obtained by continuously recording the optical density of cultures.
Anti-Bacterial Agents↗
Single-dose cefotetan vs. multiple-dose cefoxitin--antimicrobial prophylaxis in colorectal surgery. Results of a prospective, multicenter, randomized study.
This multicenter, prospective, randomized trial of short-term antimicrobial prophylaxis in colorectal surgery was designed to compare the efficacy of a single dose of cefotetan vs. multiple doses of cefoxitin. Of the 403 evaluable patients, 206 received cefoxitin (1 gm intravenously at the beginning of surgery and after 3, 6, and 12 hours, group A) and 197 cefotetan (2 gm intravenously at the beginning of surgery, group B). The two groups of patients were similar in respect to age, sex, obesity, preoperative weight loss, diabetes, type of disease, type, and mean duration of surgery. The abdominal wound infection rate was 11.2 percent in group A and 9.1 percent in group B (difference not significant). The number of patients with infections at nonsurgical sites (respiratory and urinary tract, phlebitis, and septicemia) was significantly greater in group A than in group B (17 vs. 9.1 percent, P less than .05). The mean postoperative hospital stay was similar in both the cefoxitin and cefotetan groups (15.1 vs. 15.9 days). Both regimens were inadequate in preventing infections in the presence of severe contamination of the operative field.
Adult↗
Drug resistance in cancer: an overview of the clinical aspects.
The primary cause of failure of the pharmacological treatment of cancer is the occurrence of intrinsic or acquired resistance to drugs in tumor cells. Drug resistance occurs through a variety of mechanisms and usually results from mutation or amplification of genes. Biochemical and genetic mechanisms by which tumor cells may become resistant clinically to chemotherapeutic agents are reviewed. Strategies for preventing or circumventing drug resistance are also discussed.
Antineoplastic Agents↗
Tissue distribution of antimicrobial drugs.
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Anti-Bacterial Agents↗
Ceftriaxone as short-term antimicrobial chemoprophylaxis in orthopedic surgery: a 1-year multicenter follow-up. Preliminary results of a controlled multicentre study.
In this multicentre study, 883 evaluable patients undergoing orthopedic surgery were randomly assigned to receive antiinfective prophylaxis with either ceftriaxone (Rocephin) or cefamandole. 25 patients in the ceftriaxone group and 29 patients in the cefamandole group (5.6 vs 6.5%) presented with infectious complications within the first 60 days after surgery. Delayed deep wound infections developed in only 1 of 435 patients in the ceftriaxone group compared with 4 of 413 patients in the cefamandole group. Both drugs were well tolerated. The infection rate was twice as high after surgery in conventional operating theatres than after treatment in hypersterile operating theatres (3.3 vs 6.5%); this difference is not statistically significant.
Adolescent↗