Adenosine enhances acetylcholine receptor channel openings and intracellular calcium 'spiking' in mouse skeletal myotubes.

AIMS: The autocrine activity of the embryonic isoform of the nicotinic acetylcholine receptor is crucial for the correct differentiation and trophism of skeletal muscle cells before innervation. The functional activity of extracellular adenosine and adenosine receptor subtypes expressed in differentiating myotubes is still unknown. In this study, we performed a detailed analysis of the role of adenosine receptor-mediated effects on the autocrine-mediated nicotinic acetylcholine receptor channel openings and the associated spontaneous intracellular calcium 'spikes' generated in differentiating mouse myotubes in vitro. METHODS: Cell-attached patch-clamp recordings and intracellular calcium imaging experiments were performed in contracting myotubes derived from mouse satellite cells. RESULTS: The endogenous extracellular adenosine and the adenosine receptor-mediated activity modulated the properties of the embryonic isoform of the nicotinic acetylcholine receptor in myotubes in vitro, by increasing the mean open time and the open probability of the ion channel, and sustaining nicotinic acetylcholine receptor-driven intracellular [Ca(2+) ]i 'spikes'. The pharmacological characterization of the adenosine receptor-mediated effects suggested a prevalent involvement of the A2B adenosine receptor subtype. CONCLUSION: We propose that the interplay between endogenous adenosine and nicotinic acetylcholine receptors represents a potential novel strategy to improve differentiation/regeneration of skeletal muscle.

A phase I/II trial of pixantrone (BBR2778), methylprednisolone, cisplatin, and cytosine arabinoside (PSHAP) in relapsed/refractory aggressive non-Hodgkin's lymphoma.

The purpose of the study was to evaluate the safety, efficacy, and pharmacokinetics of pixantrone (BBR2778) when substituted for etoposide in the ESHAP regimen in patients with aggressive relapsed or refractory non-Hodgkin's lymphoma. Nineteen patients received protocol therapy, consisting of pixantrone 80 mg/m2 over 1 h on day 1, methylprednisolone 500 mg on days 1 - 5, cisplatin 25 mg/m2 on days 1 - 4, and cytarabine 2000 mg/m2 on day 5. Cycles were repeated every 21 days, in the outpatient setting. Dose limiting toxicity, consisting of bone marrow suppression, occurred at the first dose level (80 mg/m2), which was defined as the recommended dose. Grade 3 and 4 toxicities were mainly hematologic. Only one patient had grade 4 febrile neutropenia. No significant decreases in ejection fraction greater than 20% occurred. Overall response rate was 58%, with 37% complete and 21% partial responses. Six of the 11 responders (55%) underwent stem cell transplant. Median time to progression and overall median survival were 5.7 months and 14.5 months, respectively. There is no significant interaction between pixantrone and the combined drugs. The recommended dose of pixantrone in combination with methylprednisolone, cytarabine, and cisplatin (PSHAP) is 80 mg/m2. PSHAP is an active salvage regimen and should be further evaluated as a pretransplant cytoreductive regimen.

Phase I study of BBR 2778, a new aza-anthracenedione, in advanced or refractory non-Hodgkin's lymphoma.

BACKGROUND: BBR 2778 is a novel aza-anthracenedione showing no cardiotoxicity and superior activity compared to doxorubicin and mitoxantrone in animal models. Objectives of this phase I study included the determination of the maximum tolerated dose (MTD), the dose limiting toxicity (DLT), clinical pharmacokinetics (PK), and antitumor activity. Patients with relapsed or refractory, advanced non-Hodgkin's lymphoma were included. PATIENTS AND METHODS: Patients were treated with a q1w x 3 schedule on the basis of a modified Fibonacci dose escalation method. Seven groups with a total of twenty-six patients were treated at dosages of 5, 10, 16.5, 25, 34, 56 or 84 mg/m2/w, respectively. RESULTS: DLT was observed on the seventh dose level with neutropenia WHO grade 4 in three of six patients. Pharmacokinetic analysis showed a large volume of distribution (13.5-17.5 l/kg), a high plasma clearance (0.65-1.74 l/h/kg) and a long elimination half-life (14.7-31.9 h). Tumor response included three complete remissions and two partial remissions. CONCLUSIONS: Neutropenia is the DLT of the new aza-anthracenedione BBR 2778. The recommend dose is 84 mg/m2 in a q1w x 3 schedule. PK data are consistent with a linear kinetic of BBR 2778 comparable to mitoxantrone. This new drug shows promising activity in intensively pretreated patients with relapsed or refractory NHL. Based on this results, phase II studies with this new compound are underway.

A phase I and pharmacokinetic study of the novel aza-anthracenedione compound BBR 2778 in patients with advanced solid malignancies.

BBR 2778 is a novel aza-anthracenedione with no cardiotoxicity in preclinical models. This Phase I dose escalation trial of BBR 2778 was conducted to determine the maximum tolerated dose, the dose-limiting toxicity, and the pharmacokinetic profile of BBR 2778 in patients with advanced solid tumors. BBR 2778 was given in three consecutive weekly 30-min i.v. infusions over a 4-week cycle (cy). Thirty patients (pts) were treated with BBR 2778 at doses ranging from 5 to 150 mg/m2/week. The dose levels 5, 10, 16.5, 25, 37.5, 75, 112.5, and 150 mg/m2/week were investigated in 4 pts (9 cy), 3 pts (3 cy), 3 pts (5 cy), 6 pts (9 cy), 1 pt (1 cy), 4 pts (9 cy), 6 pts (18 cy), and 3 pts (4 cy), respectively. The dose-limiting toxicity was neutropenia, typically occurring at day 14. Other toxicities were mild to moderate and were principally thrombocytopenia, lymphopenia, alopecia, nausea, and vomiting and blue coloration of the skin and urine. No significant cardiac toxicity was observed. The plasma dose concentration curve fitted a biexponential profile, with a rapid distribution phase followed by a prolonged elimination phase (mean t1/2,z, 12 h). BBR 2778 displayed a large volume of distribution (range, 9.7-29.7 l/kg) with a high plasma clearance rate (0.75-1.31 l/h/kg). Less than 10% of the dose was recovered in urine as unchanged drug. The maximum tolerated dose was 150 mg/m2/week for 3 weeks, every 4 weeks. On the basis of this study, the recommended dose for Phase II studies is 112.5 mg/m2/week days 1 and 8 with individual optional administration at day 15, every 4 weeks. Antitumor activity was observed in patients with breast, small cell lung carcinoma, and facial cylindroma. This trial showed that BBR 2778 has a manageable toxicity profile on a weekly schedule. This lead compound of the aza-anthracenedione family shows promising antitumor activity and deserves Phase II investigation in patients with high risk of cumulative cardiotoxicity, such as anthracycline-pretreated breast cancer patients.

A clinical phase I and pharmacokinetic study of BBR 2778, a novel anthracenedione analogue, administered intravenously, 3 weekly.

The anthracenedione analogue, BBR 2778 is an active antitumour agent preclinically and has reduced potential for cardiotoxicity compared with other similar drugs in preclinical models. BBR 2778 was administered 3 weekly by a 1 h intravenous (i.v.) infusion to 24 patients and the dose escalated rapidly from 20 to 240 mg/m2. The dose-limiting toxicity (DLT) was neutropenia, common toxicity criteria (CTC) grade 4 in 3/5 patients at 240 mg/m2. Other toxicities > or = CTC grade 3 were: vomiting, lymphopenia, thrombocytopenia and lethargy. Blue discoloration of veins and urine was also noted. In 1 patient (120 mg/m2, four cycles) left ventricular ejection reaction (LVEF) fell (CTC grade 2) but with no clinical sequelae. BBR 2778 plasma pharmacokinetics were biphasic (mean t(1/2) at 180 mg/m2 = 14.1 h) and the urinary elimination of the unchanged drug was < 10%. In a patient with previously treated small cell lung carcinoma (SCLC), a 49% reduction in measurable disease was noted with resolution of pericardial and pleural effusions (120 mg/m2 x eight cycles). From the results of this phase I study a dose of 180 mg/m2 as a 1 h infusion every 3 weeks would be recommended for phase II trials.

Clinical and pharmacological phase I study with accelerated titration design of a daily times five schedule of BBR3464, a novel cationic triplatinum complex.

OBJECTIVES: To define the maximum tolerated dose (MTD), the toxicity and pharmacokinetic profile of BBR3464, a novel triplatinum complex. PATIENTS AND METHODS: Fourteen patients with advanced solid tumors not responsive to previous antitumor treatments received BBR 3464 on a daily x 5 schedule every twenty-eighth day. The drug was given as a one-hour infusion with pre-and post-treatment hydration (500 ml in one hour) and no antiemetic prophylaxis. The starting dose was 0.03 mg/m2/day. A modified accelerated titration escalation design was used. Total and free platinum (Pt) concentrations in plasma and urine were assessed by ICP-MS on days 1 and 5 of the first cycle. RESULTS: Dose was escalated four times up to 0.17 mg/m2/day. Short-lasting neutropenia and diarrhea of late onset were dose-limiting and defined the MTD at 0.12 mg/m2. Nausea and vomiting were rare, neither neuro- nor renal toxic effects were observed. BBR3464 showed a rapid distribution phase of 1 hour and a terminal half-life of several days. At 0.17 mg/m2 plasma Cmax and AUC on day 5 were higher than on day 1, indicating drug accumulation. Approximately 10% of the equivalent dose of BBR3464 (2.2%-13.4%) was recovered in a 24-hour urine collection. CONCLUSIONS: The higher than expected incidence of neutropenia and GI toxicity might be related to the prolonged half-life and accumulation of total and free Pt after daily administrations. Lack of nephrotoxicity and the low urinary excretion support the use of the drug without hydration. The single intermittent schedule has been selected for clinical development.

Clinical pharmacokinetics of nimesulide.

Nimesulide is a selective COX-2 inhibitor used in a variety of inflammatory, pain and fever states. After healthy volunteers received oral nimesulide 100 mg in tablet, granule or suspension form the drug was rapidly and extensively absorbed. Mean peak concentrations (Cmax) of 2.86 to 6.50 mg/L were achieved within 1.22 to 2.75 hours of administration. The presence of food did not reduce either the rate or extent of nimesulide absorption. When nimesulide was administered in the suppository form, the Cmax was lower and occurred later than after oral administration; the bioavailability of nimesulide via suppository ranged from 54 to 64%, relative to that of orally administered formulations. Nimesulide is rapidly distributed and has an apparent volume of distribution ranging between 0.18 and 0.39 L/kg. It is extensively bound to albumin; the unbound fraction in plasma was 1%. The unbound fraction increased to 2 and 4% in patients with renal or hepatic insufficiency. With oral administration, the concentrations of nimesulide declined monoexponentially following Cmax. The estimated mean terminal elimination half-life varied from 1.80 to 4.73 hours. Excretion of the unchanged drug in urine and faeces is negligible. Nimesulide is largely eliminated via metabolic transformation and the principal metabolite is the 4'-hydroxy derivative (M1). Minor metabolites have been detected in urine and faeces, mainly in a conjugated form. Pharmacological tests in vivo have shown that the metabolites are endowed with anti-inflammatory and analgesic properties, although their activity is lower than that of nimesulide. Excretion in the urine and faeces accounted for 50.5 to 62.5% and 17.9 to 36.2% of an orally administered dose, respectively. The total plasma clearance of nimesulide, was 31.02 to 106.16 ml/h/kg, reflecting almost exclusive metabolic clearance. The drug has a low extraction ratio, close to 0.1. With twice daily oral or rectal administration of nimesulide, steady-state was achieved within 24 to 48 hours (2 to 4 administrations); only modest accumulation of nimesulide and M1 occurred. Gender has only a limited influence on the pharmacokinetic profiles of nimesulide and M1. The pharmacokinetic profiles of nimesulide and M1 in children and the elderly did not differ from that of healthy young individuals. Hepatic insufficiency affected the pharmacokinetics of nimesulide and M1 to a significant extent: the rate of elimination of nimesulide and M1 was remarkably reduced in comparison to the rate of elimination in healthy individuals. Therefore, a dose reduction (4 to 5 times) is required in patients with hepatic impairment. The pharmacokinetic profile of nimesulide and M1 was not altered in patients with moderate renal failure and no dose adjustment in patients with creatinine clearances higher than 1.8 L/h is envisaged. Pharmacokinetic interactions between nimesulide and other drugs given in combination [i.e. glibenclamide, cimetidine, antacids, furosemide (frusemide), theophylline, warfarin and digoxin] were absent, or of no apparent clinical relevance.

Cytotoxicity, cellular uptake and DNA binding of the novel trinuclear platinun complex BBR 3464 in sensitive and cisplatin resistant murine leukemia cells.

BBR 3464 is a novel trinuclear platinum anticancer agent designed on the hypothesis that new clinically useful platinum based anticancer agents should have novel structures unrelated to those of agents currently used in the clinic. BBR 3464 shows outstanding cytotoxicity both against sensitive (L1210) and cisplatin (CDDP) resistant (L1210/CDDP) murine leukemia cell lines. In fact, BBR 3464 is 30 times more cytotoxic than CDDP against the L1210 cell line and also shows a complete lack of cross-resistance in L1210/CDDP (resistance index 0.8). BBR 3464 and CDDP cellular uptake in L1210 and L1210/CDDP eells and binding to nuclear DNA were studied after incubation with 3.34 microM BBR 3464 and 66.7 microM CDDP, respectively, for up to 4 hours with 133.4 and 266.8 microM of CDDP and 6.68, 13.36 microM of BBR 3464 for 2 hours to determine concentration-cellular uptake and concentration-DNA binding relationships. CDDP and BBR 3464 cellular uptake and their extent of binding to DNA increased as function of time and in a concentration dependent manner in both cell lines. CDDP uptake and binding to DNA were higher in L1210 eells than in L1210/CDDP cells whereas BBR 3464 uptake and binding to DNA were similar in both cell lines. In L1210/CDDP murine leukemia cells BBR 3464 seems to overcome the CDDP cross-resistance related to impaired accumulation and reduction of binding to DNA.

Pharmacokinetics and pharmacodynamics of torasemide and furosemide in patients with diuretic resistant ascites.

BACKGROUND/AIM: To evaluate the pharmacokinetics and pharmacodynamics of furosemide and torasemide in patients with cirrhosis and diuretic resistant ascites. METHODS: Eighteen patients were randomly allocated to receive intravenous torasemide (40 mg) or furosemide (80 mg). The renal response to these drugs was assessed in baseline conditions and in the 24 h following drug administration together with plasma and urinary concentrations of furosemide, torasemide and its metabolites. RESULTS: Torasemide induced significantly greater diuretic and natriuretic effects than furosemide in the first hour after drug administration. No other significant differences between the two drugs were observed with respect to the renal response to these drugs. Torasemide reached a lower maximum plasma concentration than furosemide, but the former drug had a longer apparent terminal half-life and lower renal and non-renal clearances. Comparing these results with those previously reported in healthy subjects, both drugs showed a reduced elimination rate through renal and non-renal routes, and a larger distribution to body fluids. As a consequence, the half-life of both drugs was longer than in healthy subjects. Urinary excretion of pharmacologically active species, however, was quantitatively unchanged after torasemide administration, whereas it was reduced after furosemide. Finally, the natriuretic potency of both drugs was markedly reduced in these patients. CONCLUSIONS: The pharmacokinetics and pharmacodynamics of torasemide and furosemide are markedly altered in patients with diuretic resistant ascites.

Stereoselective pharmacokinetics of moguisteine metabolites in healthy subjects.

We studied the pharmacokinetics of moguisteine, a racemic non-narcotic peripheral antitussive drug, in 12 healthy male subjects after a single oral administration of 200 mg. The unchanged drug was absent in plasma and urine of all subjects. Moguisteine was immediately and completely hydrolyzed to its main active metabolite, the free carboxylic acid M1. Therefore, we evaluated the kinetic profiles of M1, of its enantiomers R(+)-M1 and S(-)-M1, and of M1 sulfoxide optical isomers M2/I and M2/II by conventional and stereospecific HPLC. Maximum plasma concentrations for M1 (2.83 mg/l), M2/I (0.26 mg/l) and M2/II (0.40 mg/l), were respectively reached at 1.3, 1.6 and 1.5 h after moguisteine administration. Plasma concentrations declined after the peak with mean apparent terminal half-lives of 0.65 h (M1), 0.88 h (M2/I) and 0.84 h (M2/II). Most of the administered dose was recovered in urine within 6 h from moguisteine treatment. The systemic and renal clearance values indicated high renal extraction ratio for all moguisteine metabolites, and particularly for M1 sulfoxide optical isomers. Plasma concentration-time profiles and urinary excretion patterns for M1 enantiomers R(+)-M1 and S(-)-M1 were quite similar. Thus, for later moguisteine pharmacokinetic evaluations the investigation of the plasma concentration-time curve and the urinary excretion of the sole racemic M1 through non-stereospecific analytical methods may suffice in most cases.

HPLC method for the quantitation of cispentacin enantiomers in rat urine.

The two enantiomers of cispentacin, an antifungal antibiotic, are determined by reversed phase HPLC, after derivatization with Marfey's reagent, in 24 h urine samples collected from rats treated sc and iv with 20 mg/kg cispentacin racemate obtained by synthesis. The application range of the method is 25-250 mg/L for each enantiomer with a precision of 4.0-9.0%. Comparison with an authentic sample of natural origin (-)-cispentacin indicated that (-) enantiomer is excreted unchanged in smaller percentage than (+) enantiomer, which is almost completely eliminated as such.

Characterization of cisplatin-glutathione adducts by liquid chromatography-mass spectrometry. Evidence for their formation in vitro but not in vivo after concomitant administration of cisplatin and glutathione to rats anc cancer patients.

After incubation of equimolar amounts of cisplatin (CDDP) and glutathione (GSH) in phosphate buffer pH 7.4 at 37 degrees C, we detected two CDDP-GSH adducts whose structures, characterized by LC-MS, corresponded to cis-[Pt(NH3)2Cl(SG)] and cis-([Pt(NH3)2Cl]2(mu-SG))+. The latter is a new CDDP-GSH adduct, which was postulated but never structurally characterized so far. Rats and patients were given a 15-min intravenous infusion of CDDP (10 mg/kg to rats and 25 mg/m2 to patients) preceded by a GSH intravenous administration (200 mg/kg to rats as a bolus and 1.5 g/m2 to patients as a 15-min infusion). After the administrations, CDDP-GSH adducts were absent in rat and human plasma ultrafiltrates. The discrepancy between in vitro and in vivo findings can be explained based on pharmacokinetic considerations.

[Pharmacokinetics of chiral drugs]. / Farmacocinetica di principi attivi chirali.

The rate and extent of passive pharmacokinetic processes, such as passive gastrointestinal absorption, tissue distribution and glomerular filtration, depend on the physical-chemical properties of a drug. In the case of chiral drugs, since enantiomers have the same properties, in general we would not expect passive processes to be stereoselective. On the contrary, enantioselectivity would occur for processes involving a drug interaction with a chiral macromolecule (e.g. receptors, enzymes, transport proteins), like the carrier-mediated absorption, protein binding, active renal and biliary secretion, metabolism. However, a few exceptions aside, the degree of stereoselectivity of these processes is relatively modest. In this paper we reviewed several examples of stereoselective kinetic processes and discussed the limits of the interpretation of pharmacokinetic data resulting from the application of non-stereospecific analytical methods.

Assay of moguisteine metabolites in human plasma and urine: conventional and chiral high-performance liquid chromatographic methods.

Moguisteine is a novel peripheral non-narcotic antitussive agent. Pharmacokinetic studies in animal and in man showed that no unchanged drug is present in plasma, urine and faeces after oral administration. The main active metabolite, M1, is the free carboxylic acid of moguisteine, which maintains a stereogenic centre and consists of R(+)-M1 and S(-)-M1 enantiomers. M1 is partly metabolized to M2, its sulfoxidation derivative. A conventional HPLC method is described for the simultaneous determination of M1 and M2 in human plasma and urine after administration of therapeutic moguisteine doses. Plasma samples, previously acidified with phosphoric acid, are extracted with dichloromethane; urine samples are analyzed after appropriate dilution with methanol. Chromatography is performed using a Lichrosorb RP2 column and a linear gradient. M1 enantiomers can be determined in plasma extracts and urine samples by a chiral HPLC method using a beta-cyclodextrin column. The analytical characteristics of both HPLC procedures proved to be adequate to analyze samples of subjects treated with therapeutic doses of moguisteine during clinical pharmacokinetic studies.

Direct HPLC separation of enantiomers of main moguisteine metabolite: comparison of different stationary phases.

Moguisteine is a new non-narcotic antitussive agent. The molecule contains a chiral centre, which is maintained in the metabolite structure. The unchanged drug is not found in the plasma of treated animals or humans. The main moguisteine metabolite, M1, is the free racemic acid generated by hydrolysis of the ethyl-ester group of moguisteine. HPLC separation of M1 enantiomers was attempted using various chiral stationary phases. Separation of the enantiomers was achieved with alpha-1-AGP and beta-cyclodextrin columns, which showed similar enantioselectivity and good resolution. However, the routine application of alpha-1-AGP columns turned out to be difficult, due to the limiting low flow rate which displayed baseline problems and progressive loss of resolution. beta-Cyclodextrin columns showed greater efficiency than alpha-1-AGP columns, as the former allows reproducible separation and can easily be applied to biological sample analysis in pharmacokinetic studies.

S-acetyl- and S-phenylacetyl-glutathione as glutathione precursors in rat plasma and tissue preparations.

S-acetyl- and S-phenylacetyl-glutathione derivatives were synthesized by using a new procedure. The derivatives were incubated with rat plasma and red blood cells, and also with cytosol from rat liver, kidney and heart, or tissue slices from rat heart, kidney and liver. A limited hydrolysis of the compounds occurs in plasma, whereas hydrolysis occurs to a larger extent in tissue cytosols. Both purified and crude gamma-glutamyl-transpeptidase from different sources recognized the S-acetyl- and S-phenylacetyl derivatives as substrates. Intracellular glutathione increases after incubating the derivatives with red blood cells. A potential role of S-acetyl- and S-phenylacetyl-glutathione in replenishing cells with exogenous glutathione is envisaged.

The pharmacokinetic profile of nimesulide in healthy volunteers.

After oral administration of nimesulide 100mg in tablet, granule or suspension to healthy volunteers, the drug was rapidly and extensively absorbed. Mean peak plasma concentrations of 2.86 to 4.58 mg/L were achieved within 1.22 to 3.83 hours of administration. The presence of food did not reduce either the rate or the extent of nimesulide absorption. When administered in suppository form, nimesulide peak plasma concentrations were lower and occurred later than those achieved after oral administration; the bioavailability of nimesulide given by suppository ranged from 54 to 96%, relative to that of orally administered formulations. Nimesulide is rapidly distributed, principally throughout the extracellular fluid compartment; values for volume of distribution ranged from 0.19 to 0.39 L/kg. Nimesulide is extensively bound to plasma proteins: at concentrations ranging from 0.5 to 10 mg/L, the unbound fraction varied between 0.7 and 4.0%. With oral administration, nimesulide concentrations decline monoexponentially following peak levels. The estimated mean terminal half-life for nimesulide varied from 1.96 to 4.73 hours. Excretion of unchanged drug in urine and faeces is negligible. Nimesulide is mainly eliminated by metabolic transformation and the principal metabolite is the 4'-hydroxy derivative. The presence of other metabolites is being evaluated. Excretion of nimesulide metabolites in the urine and faeces accounts for about 80 and 20% of the administered dose, respectively. Total plasma clearance of nimesulide was 39.7 to 90.9 ml/h/kg, reflecting almost exclusive metabolic clearance. The drug has a low extraction ratio, close to 0.1. Differences in gender have only a limited influence on the pharmacokinetic profile of nimesulide and its hydroxylated metabolite. With twice-daily administration of nimesulide 100 mg (tablets) or 200mg (suppositories), steady-state is achieved within 24 to 36 hours (2 to 3 administrations). With oral nimesulide 100mg twice daily, only modest accumulation of nimesulide and its 4'-hydroxy derivative occurs (Rmin, 1.59 for nimesulide and 1.46 for the hydroxylated metabolite).

Teicoplanin metabolism in humans.

Teicoplanin, a lipoglycopeptide antibiotic, consists of five major components (A2-1 through A2-5), one hydrolysis component (A3-1), and four minor components (RS-1 through RS-4). All the major components contain an N-acyl-beta-D-glucosamine, but they differ in the lengths and branchings of their acyl-aliphatic chains. Previous studies with radiolabeled teicoplanin in rats and humans have shown that the drug is eliminated by the renal route and that metabolic transformation is very minor, about 5%. A possible metabolic transformation of teicoplanin into A3-1 was also suggested. In the present study in humans, two metabolites (metabolites 1 and 2; 2 to 3% of total teicoplanin) were isolated after intravenous administration of radiolabeled teicoplanin. After purification, their structures were determined by fast atom bombardment mass spectroscopy and 1H nuclear magnetic resonance spectroscopy on the basis of the well-known correlations established in this field, and they were found to be new teicoplaninlike molecules, bearing 8-hydroxydecanoic and 9-hydroxydecanoic acyl moieties. This metabolic transformation is likely due to hydroxylation in the omega-2 and omega-1 positions for metabolites 1 and 2, respectively, of the C-10 linear side chain of component A2-3. This might explain the low extent of metabolism of teicoplanin if we consider that only component A2-3 has a linear chain that is susceptible to such oxidation.