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Clinafloxacin (CI-960) is a potent broad-spectrum, fluoroquinolone antibiotic that has been studied for parenteral and oral administration in patients with serious infections. The objectives of these studies were to examine the pharmacokinetics and safety of clinafloxacin following administration of single and twice-daily intravenous (i.v.) and oral doses to volunteers. Plasma and urine samples were assayed by validated liquid chromatographic methods, and pharmacokinetic parameter values were determined by noncompartmental methods. Safety was evaluated by clinical observation and laboratory tests. Absorption was rapid after oral administration, with maximum concentrations in plasma (C(max)) generally occurring within 2 h. Concentrations in plasma declined biexponentially, with an average terminal half-life of 4 to 6 h after single doses and 5 to 7 h after multiple doses. Increases in C(max) and area under the concentration-time curves (AUC) were generally proportional to the dose. The volume of distribution was much greater than total body water. Approximately 40 to 75% of the clinafloxacin doses were excreted unchanged into urine. Absolute bioavailability of orally administered clinafloxacin was approximately 90% and did not change with increasing dose. Therefore, switching patients from i.v. to oral dosing should achieve similar concentrations in plasma. The tolerability of clinafloxacin was acceptable. No serious adverse events occurred. C(max) values and minimum plasma clinafloxacin concentrations during multiple dosing exceeded MICs for a wide range of organisms.

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As the primary route for elimination of clinafloxacin is renal clearance (CL(R)) of unchanged drug, studies were conducted to determine the pharmacokinetic profile of clinafloxacin following administration to young and elderly subjects, subjects with various degrees of renal function, and subjects requiring dialysis. These were open-label studies in which subjects received single oral clinafloxacin doses. Sixteen young subjects (18 to 35 years old) and 16 elderly subjects (>65 years old) were enrolled in a study comparing pharmacokinetic profiles of clinafloxacin in young and elderly subjects. Twenty subjects having various degrees of renal function were enrolled into one of three groups based on degree of renal function as measured by creatinine clearance (CL(CR)). Twelve subjects with severe renal impairment requiring dialysis enrolled in a third study. Clinafloxacin was generally well tolerated by all subjects. Clinafloxacin pharmacokinetic profiles in elderly subjects were dependent only on age-related decreases in renal function. Clinafloxacin maximum concentrations in plasma, areas under the concentration-time curves, and terminal elimination half-life values increased with decreasing CL(CR) values. Total apparent body clearance of clinafloxacin from the plasma after oral administration (CL(oral)) and CL(R) were dependent on CL(CR) according to the following relationships: CL(oral) = 2.3. CL(CR) + 77 and CL(R) = 1.74. CL(CR). Hemodialysis had no significant effect on clinafloxacin clearance. Based on the relationship between CL(CR) and clinafloxacin CL(oral) and CL(R) values, the clinafloxacin dose should be halved in patients having a CL(CR) of <40 ml/min. Further dose adjustment is not warranted in patients requiring hemodialysis.

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Many fluoroquinolone antibiotics are inhibitors of cytochrome P450 enzyme systems and may produce potentially important drug interactions when administered with other drugs. Studies were conducted to determine the effect of clinafloxacin on the pharmacokinetics of theophylline, caffeine, warfarin, and phenytoin, as well as the effect of phenytoin on the pharmacokinetics of clinafloxacin. Concomitant administration of 200 or 400 mg of clinafloxacin reduces mean theophylline clearance by approximately 50 and 70%, respectively, and reduces mean caffeine clearance by 84%. (R)-Warfarin concentrations in plasma during clinafloxacin administration are 32% higher and (S)-warfarin concentrations do not change during clinafloxacin treatment. An observed late pharmacodynamic effect was most likely due to gut flora changes. Phenytoin has no effect on clinafloxacin pharmacokinetics, while phenytoin clearance is 15% lower during clinafloxacin administration.

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This study evaluated the steady-state pharmacokinetics and dose proportionality of troglitazone, metabolite 1 (sulfate conjugate), and metabolite 3 (quinone metabolite) following administration of daily oral doses of 200, 400, and 600 mg troglitazone for 7 days (per dosing period) to 21 subjects. During each dosing period, plasma samples were collected predose on days 1, 5, 6 and 7 and serially for 24 hours on day 7. Steady-state plasma concentrations for troglitazone, metabolite 1, and metabolite 3 were achieved by day 7. Troglitazone was rapidly absorbed with mean tmax values of 2.7 to 2.9 hours. Mean Cmax and AUC(0-24) values for troglitazone, metabolite 1, and metabolite 3 increased proportionally with increasing troglitazone doses over the clinical dose range of 200 mg to 600 mg administered once daily. Mean troglitazone CL/F, percent fluctuation, and AUC ratios of metabolite 1 and metabolite 3 to troglitazone were similar across dose groups. These data suggest that the pharmacokinetics and disposition of troglitazone and its metabolites are independent of dose over the dose range studied. Thus, troglitazone, metabolite 1, and metabolite 3 displayed linear pharmacokinetics at steady-state.

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Fifteen healthy women participated in a study to determine the effect of multiple doses of troglitazone on the pharmacokinetics of Ortho-Novum 1/35 (35 micrograms ethinyl estradiol [EE] and 1 mg norethindrone [NE]). Participants received three cycles (21 days each of active drug followed by 7 days without medication) of Ortho-Novum. During the third cycle, participants also received troglitazone 600 mg qd for 22 days. Pharmacokinetic profiles of EE and NE were determined on day 21 of the second and third cycles. Progesterone and sex hormone binding globulin (SHBG) levels were also measured. Troglitazone decreased EE Cmax and AUC(0-24) by 32% and 29%, respectively. Likewise, troglitazone decreased NE Cmax and AUC(0-24) by 31% and 30%, respectively. Plasma SHBG concentrations increased from 113 nmol/L during cycle 2 to 220 nmol/L during cycle 3. Troglitazone reduced plasma unbound AUC for NE by 49%. Serum progesterone levels were lower than 1.5 ng/mL on all occasions. Thus, coadministration of troglitazone and Ortho-Novum decreases the systemic exposure to EE and NE. A higher dose of oral contraceptive or an alternate method of contraception should be considered for patients treated with troglitazone.

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Twelve healthy subjects participated in a study to determine the effect of multiple doses of troglitazone on the steady-state pharmacokinetics of digoxin. Subjects received digoxin 0.25 mg orally once daily on days 1 through 20 and 400 mg of troglitazone orally once daily on days 11 through 20. Serial plasma samples and 24-hour urine samples collected before and after the doses on days 10 and 20 were analyzed for digoxin using a radioimmunoassay method. Eleven subjects completed the study. Administration of multiple oral doses of digoxin and troglitazone was well tolerated. Mean values for maximum concentration (Cmax), time to Cmax (tmax), and area under the concentration-time curve from 0 to 24 hours (AUC0-24) of digoxin on day 10 were similar to those on day 20. Mean day 10 digoxin values for minimum concentration (Cmin), apparent oral clearance (Cl/F), total urinary excretion from 0 to 24 hours (Ae0-24), and renal clearance (Clr) were also similar to corresponding values on day 20. Thus, concomitant administration of multiple-dose troglitazone does not alter the steady-state pharmacokinetics of digoxin.

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Twelve patients with type II diabetes and 12 age-, weight-, and gender-matched healthy subjects participated in a study comparing the pharmacokinetics of troglitazone, metabolite 1 (sulfate conjugate), and metabolite 3 (quinone) after oral administration of 400 mg of troglitazone every morning for 15 days. Serial plasma samples collected after the dose on days 1 and 15 were analyzed for troglitazone, metabolite 1, and metabolite 3 using a validated HPLC method. Steady state plasma concentrations of troglitazone and its metabolites were achieved by the fifth day of troglitazone administration in both groups. Mean day 15 Cmax, tmax, AUC0-24, and Cl/F values of troglitazone were 1.54 micrograms/mL, 3.25 hours, 15.6 micrograms.hr/mL, and 461 mL/min, respectively, in patients with type II diabetes. Corresponding parameter values were 1.42 micrograms/mL, 2.63 hours, 12.5 micrograms.hr/mL, and 558 mL/min, respectively, in healthy subjects. Elimination t1/2 was approximately 24 hours in both groups. Mean day 15 pharmacokinetic parameter values for metabolite 1 and metabolite 3 were similar in the two groups. Ratio of AUC of metabolite 1 to troglitazone was 6.2 and 6.7, respectively, in patients and in healthy subjects. Ratio of AUC of metabolite 3 to troglitazone was 1.1 in both groups. Thus, steady-state pharmacokinetics and disposition of troglitazone and its metabolites in patients with type II diabetes were similar to those in healthy subjects.

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The single-dose tolerance and pharmacokinetics of clinafloxacin, a new fluoroquinolone antibacterial agent, were evaluated in healthy volunteers. Single oral doses of 25, 50, 100, and 200 mg were well tolerated. Adverse events after placebo and clinafloxacin were similar, with mild drowsiness, dizziness, headache, and rash being reported most frequently. The frequency and intensity of side-effects did not increase with dose. Clinafloxacin was rapidly absorbed, with Cmax occurring at approximately 40 min postdose. Plasma concentrations increased proportionately and, following 100 or 200 mg doses, remained above MIC90s required for most nosocomial pathogens for at least 12 h. Clinafloxacin elimination half-life averaged 5.2 h and renal clearance was approximately 200 mL/min. About 50% of the administered dose was excreted unchanged in the urine.

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We report the first case of 90Y-conjugated monoclonal antibody (MoAb) administration for human radioimmunotherapy. Ten mCi 90Y-labeled antiidiotype (anti-Id) MoAb were administered to a patient with B-cell lymphoma whose tumor successfully imaged with 111In-labeled anti-Id MoAb. No significant toxicities were observed. More than 2 g of unlabeled anti-Id MoAb were administered while clearing the circulating IgM idiotype prior to administration of the 90Y-MoAb. Transient partial regression of disease was observed. Serial fine needle aspirations of a malignant lymph node documented in vivo anti-Id penetration into a site that did not image by radioimmunoscintigraphy. The radiosensitivity of B-cell lymphoma, the tumor specificity of anti-Id, the antitumor activity of anti-Id alone, and the safe administration of 10 mCi 90Y-labeled anti-Id MoAb in this report suggest further investigation of this radioimmunoconjugate for therapy of B-cell lymphoma is warranted.

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The methylation and amplification of mouse mammary tumor virus (MuMTV) proviral DNA was investigated in normal, premalignant, and malignant tissues of GR/A mice. The proviral methylation pattern was examined with the restriction enzyme HhaI, which fails to cleave methylated DNA. MuMTV proviral DNA from liver, kidney, and heart was highly methylated. Proviral DNA was somewhat undermethylated in mammary gland cells from virgin and lactating mice and extensively undermethylated in cells from premalignant outgrowths, pregnancy-dependent tumors, and pregnancy-independent tumors. The restriction enzyme SacI was used to detect additional proviruses in the same cells. No additional proviral copies of MuMTV were detected in liver, kidney, or heart cells or in mammary gland cells from virgin mice. Some mammary gland cells from lactating mice appeared to contain additional copies of the endogenous, highly oncogenic GT-MTV-2 provirus. Premalignant outgrowth, pregnancy-dependent tumor, and pregnancy-independent tumor cells contained an average of two to three additional copies per cell of the GT-MTV-2 provirus. Thus, neoplasia in GR/A mice was directly associated with quantized increases in MuMTV proviral DNA undermethylation and GR-MTV-2 proviral DNA amplification. Restriction enzyme analysis suggested that premalignant outgrowths and pregnancy-dependent tumors both consisted largely of heterogenous cell populations, although some evidence of clonal dominance was detected.

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