Subcutaneous versus intravenous formulation of trastuzumab for HER2-positive early breast cancer: updated results from the phase III HannaH study.

BACKGROUND: HannaH (NCT00950300) was a phase III, randomized, international, open-label study that compared pharmacokinetics (PK), efficacy, and safety of two different trastuzumab formulations [subcutaneous (s.c.) and intravenous (i.v.)] in HER2-positive, operable, locally advanced, or inflammatory breast cancer in the neoadjuvant/adjuvant setting. The co-primary end points, to show noninferiority of s.c. versus i.v. trastuzumab in terms of serum concentration (Ctrough) and pathologic complete response (pCR) were met; safety profiles were comparable at 12 months' median follow-up. Secondary end points included safety and tolerability, PK profile, immunogenicity, and event-free survival (EFS). We now report updated safety and efficacy data after a median follow-up of 20 months. PATIENTS AND METHODS: Patients (N = 596) were treated with eight cycles of neoadjuvant chemotherapy, administered concurrently with 3-weekly s.c. trastuzumab (fixed dose of 600 mg) or the standard weight-based i.v. method. Following surgery, patients continued trastuzumab treatment to complete 1 year of therapy. Updated analyses of PK, efficacy, safety, and immunogenicity data were carried out. RESULTS: s.c. trastuzumab was generally well tolerated and the incidence of adverse events (AEs), including grade 3 or 4 AEs, between treatment groups was comparable. A slightly higher incidence of serious AEs (SAEs), mainly due to infections, was reported with s.c. treatment {64 [21.5%; 95% confidence interval (CI) 17.0%-26.7%] versus 42 (14.1%; 95% CI 10.4%-18.6%) in the i.v. group}; however, the differences were small and often based on rare events, with no observable pattern across reported events. An early analysis of EFS showed rates of 95% in both groups 1 year postrandomization. Exploratory analyses did not reveal an association between toxicity and body weight or exposure. CONCLUSIONS: Overall, the safety profile of s.c. trastuzumab was consistent with the previously published data from HannaH and the known safety profile of i.v. trastuzumab. EFS rates were comparable between the i.v. and s.c. groups. CLINICAL TRIAL NUMBER: NCT00950300.

Adjuvant intravesicular pharmacotherapy for superficial bladder cancer.

In 1990, bladder cancer, excluding carcinoma in situ, was estimated to contribute 49,000 cases of cancer. In men 75 years old or older, it became the fifth leading cause of cancer deaths. Of patients with bladder cancer, 75%-80% initially present with superficial bladder tumors. Treatment of these tumors has three objectives: 1) to eradicate existing disease, 2) to provide prophylaxis against tumor recurrence, and 3) to avoid deep invasion into the muscle layers of the bladder. Transurethral resection is the primary treatment to eradicate superficial bladder tumors, but 40%-80% of these tumors recur. Because of these high recurrence rates, adjuvant intravesicular pharmacotherapy with cytotoxic and immunomodulatory drugs has gained widespread use. The past two decades of clinical investigations in superficial bladder cancer have provided valuable information on the biology and treatment of the disease. Multivariate analyses have indicated that tumor grade and stage are the most important prognostic variables commonly available to the clinician to identify the patient at greatest risk of developing muscle-invasive or metastatic bladder cancer. These studies have also identified groups at low risk for tumor recurrence and invasive bladder cancer. Randomized trials have shown that recurrence rates are decreased by adjuvant intravesicular pharmacotherapy with a number of drugs: bacillus Calmette-Guérin vaccine (BCG), doxorubicin, ethoglucid (Epodyl), mitomycin-C, teniposide, and thiotepa. However, few studies indicate that adjuvant intravesicular pharmacotherapy can prevent progression to invasive bladder cancer in the high-risk patient with superficial bladder cancer. Additional clinical trials are needed to determine whether such therapy can prevent invasive and metastatic bladder cancer and improve disease-free survival in this group. In addition, the identification of tests (e.g., monoclonal antibody tests, chromosomal analyses, and tumor marker assays) that can help to identify high-risk patients is needed to better develop therapeutic strategies for superficial bladder cancer.

Reversal by cefoperazone of resistance to etoposide, doxorubicin, and vinblastine in multidrug resistant human sarcoma cells.

The cephalosporins are a family of semisynthetic antibiotics, some of which have structural features associated with substrates for the multidrug transporter, P-glycoprotein. The activity of a series of six cephalosporins in reversing multidrug resistance (MDR) was examined in MDR variants (Dx5 cells) of the human sarcoma line MES-SA. Dx5 cells express high levels of the mdr1 gene product P-glycoprotein and are 25- to 30-fold resistant to doxorubicin (DOX), etoposide (VP-16), and vinblastine (VBL). Cytotoxicity was measured by the MTT assay. Cefoperazone (1.0 mM) was the most effective modulator of MDR, lowering the IC50 for VP-16 by 29-fold (29x), for VBL by 16x, and for DOX by 14x. Ceftriaxone at 1.0 mM produced 10x modulation of VP-16 cytotoxicity, 8x for DOX, and 2x for VBL. The reversal of resistance was concentration dependent, decreasing to 4x and 5x, respectively, for DOX with 0.25 mM cefoperazone and ceftriaxone. No modulation of cytotoxicity was observed in the parental MES-SA cells, which do not express mdr1. Cefazolin, cefotetan, cephradine, and ceftazidime were ineffective, producing less than 5x modulation of DOX at 1.0 mM. Among these cephalosporins, cefoperazone and ceftriaxone were the most highly protein bound in the media (30 and 52%), and the most lipid soluble, with octanol/water partitioning coefficients of -0.49 and -0.60. Varying the serum concentration in medium from 5 to 50% had less than a two-fold effect on the modulation of MDR by ceftriaxone. The ability to reverse MDR among these agents is associated with lipid solubility, high protein binding, a polycyclic planar geometry, and the presence of the piperazine group in cefoperazone. These data and the potential for achieving high tissue concentrations indicate that cefoperazone merits further study as a modulator of MDR.

Cardiotoxicity of epirubicin and doxorubicin: assessment by endomyocardial biopsy.

Forty-two evaluable endomyocardial biopsies were obtained from 29 patients treated with epirubicin, the 4'-epimer of doxorubicin in cumulative doses ranging from 147 mg/m2 to 888 mg/m2. In this study of the Northern California Oncology Group, myofibrillar loss and sarcoplasmic vacuolization were identified and shown to be identical to those previously described for doxorubicin. However, when these biopsies were compared to 119 biopsies obtained from 98 patients treated with doxorubicin, milligram for milligram, epirubicin caused less endomyocardial injury than doxorubicin (P = 0.0013). Age, sex, type of primary malignancy, prior cardiac disease, and hypertension did not influence the degree of histologically demonstrated anthracycline injury induced by epirubicin.

Should Therapeutic Drug Monitoring for Monoclonal Antibodies Remain the Exception or Become the Norm?

Therapeutic drug monitoring (TDM) aims to maintain circulating drug concentrations at a desired level to optimize clinical outcome. The vast majority of marketed drugs do not require TDM, suggesting the clinical benefit of TDM has not been sufficiently demonstrated in most cases. With the continued emergence and prominence of monoclonal antibodies (mAbs) as drugs, especially in inflammation and cancer therapeutic areas, we are at a juncture to consider applicability of TDM for mAbs.

The biology and treatment of superficial bladder cancer.

Management of the superficial bladder cancer patient consists of two complementary but separate therapeutic goals: treatment of the existing tumor(s) and prevention of tumor recurrence. At present, the stage, grade, and multicentricity are the major determinants in the natural and therapeutic history of the disease. Although intravesical instillation of chemotherapeutic agents has been used for greater than 20 years, neither its exact role nor the optimal dose or schedule of administration have been established. To date, no dramatic differences in efficacy between the agents commonly used for intravesical chemotherapy, either as definitive therapy or prophylaxis, have been appreciated. These agents do appear to lower the recurrence rate as well as extend the disease-free interval. Since the most thorough experience is with thiotepa, it is the drug against which other agents should be compared in terms of both efficacy and toxicologic evaluation. Different administration schedules and methodologies need further study, such as the utility of continuous bladder irrigation, the use of sequential chemotherapeutic agents to gain cell synchronization, and the use of multiple drug regimens. Because there are multiple factors that influence the occurrence and recurrence of bladder cancer, combined modality therapy deserves testing. Modes of therapy that could be used together because they act through different mechanisms are intravesical chemotherapy, radioactive needle implants, carcinogen modifiers such as pyridoxine, chemoprotective agents such as retinoic acid, and immune stimulants such as BCG. These studies should be performed in a randomized prospective controlled fashion, which may require cooperative multi-institutional involvement to accrue adequate numbers of patients. At this time there are a number of important questions that remain to be answered concerning the treatment of superficial bladder cancer: (1) does this mode of therapy affect overall survival, (2) does prophylactic intravesical chemotherapy alter the incidence of subsequent muscle invasive disease, (3) does intravesical chemotherapy alter the sites, incidence, or responsiveness to systemic chemotherapy of subsequent metastatic disease, and (4) and what is the optimal timing and duration of prophylactic therapy from a cost-effectiveness standpoint?

Superficial bladder cancer: the primacy of grade in the development of invasive disease.

Tumor characteristics thought to predict for development of deep muscle invasion after resection of superficial bladder cancer were retrospectively analyzed in 252 patients with transitional cell carcinoma of the bladder at Stanford University Medical Center. Stage 0 patients accounted for 190 of the patient population (75.5%), while stage A and B1 comprised 51 (20%) and 11 (4.5%), respectively. The median follow-up time was 62 months. Forty-three patients subsequently developed deep muscle invasion; these included 24 (12.6%), 14 (27.5%), and 5 (45.5%) of stage 0, A, and B1 patients (P = .002), or 15 (10%), 15 (9%), and 13 (33%) of grade 1, 2, and 3 tumors (P = .001), respectively. When analyzed by univariate logistic regression, grade (P = .0001) and stage (P = .0118) were significant predictors for invasive disease. Site of tumor and number of tumors at presentation were not significant factors for invasion deep into the bladder wall. When multiple logistic regression was performed, only grade remained as a significant tumor variable to predict for invasive disease (P less than .0091). Risk of invasive disease did not appear to increase with increasing number of recurrences, remaining at approximately an 11% invasion rate through 12 recurrences. In this analysis, grade was the most significant tumor variable in superficial bladder cancer predicting for the development of invasive carcinoma. Future clinical trials for definitive or adjuvant therapy of this disease must stratify for this variable.

Phase I trial of etoposide with cyclosporine as a modulator of multidrug resistance.

PURPOSE: To determine the maximum-tolerated dose (MTD) of cyclosporine (CsA) infusion administered with etoposide for 3 days in patients with cancer. PATIENTS AND METHODS: Of the 72 registered patients, 26 were treated initially with CsA and etoposide. Forty-six received etoposide alone until disease progression, and 31 of these proceeded to CsA and etoposide. CsA was administered as a 2-hour loading dose (LD) and as a 3-day continuous infusion (CI); doses were escalated from 2 to 8 mg/kg LD and 5 to 24 mg/kg/d CI. RESULTS: Fifty-seven patients were treated with 113 cycles of CsA with etoposide. Steady-state serum CsA levels (nonspecific immunoassay) more than 2,000 ng/mL were achieved in 91% of the cycles at CsA doses > or = 5 mg/kg LD and > or = 15 mg/kg/d CI. The major dose-related toxicity of CsA was reversible hyperbilirubinemia, which occurred in 78% of the courses with CsA levels > 2,000 ng/mL. Myelosuppression and nausea were more severe with CsA and etoposide. Other CsA toxicities included hypomagnesemia, 60%; hypertension, 29%; and headache, 21%. Nephrotoxicity was mild in 12% and severe in 2% of the cycles. Tumor regressions occurred in four patients after the addition of CsA (one non-Hodgkin's lymphoma, one Hodgkin's disease, and two ovarian carcinomas). Biopsy procedures for tumors from three of the four patients who responded were performed, and the results were positive for mdr1 expression. CONCLUSIONS: Serum CsA levels of up to 4 mumol/L (4,800 ng/mL) are achievable during a short-term administration with acceptable toxicities when administered in combination with etoposide. The CsA dose that is recommended in adults is a LD of 5 to 6 mg/kg, followed by a CI of 15 to 18 mg/kg/d for 60 hours. CsA blood levels should be monitored and the doses should be adjusted to achieve CsA levels of 2.5 to 4 mumol/L (3,000 to 4,800 ng/mL). Reversible hyperbilirubinemia may be a useful marker of inhibition by CsA of P-glycoprotein function. When used with high-dose CsA, etoposide doses should be reduced by approximately 50% to compensate for the pharmacokinetic effects of CsA on etoposide (Lum et al, J Clin Oncol, 10:1635-1642, 1992).

Alteration of etoposide pharmacokinetics and pharmacodynamics by cyclosporine in a phase I trial to modulate multidrug resistance.

PURPOSE: To determine the effects of high-dose cyclosporine (CsA) infusion on the pharmacokinetics of etoposide in patients with cancer. PATIENTS AND METHODS: Sixteen patients were administered 20 paired courses of etoposide and CsA/etoposide. Etoposide was administered daily for three days, alone or with CsA, which was delivered by a loading dose and 3-day infusion. Etoposide was measured by high-performance liquid chromatography (HPLC) and serum CsA by nonspecific immunoassay. Etoposide pharmacokinetics included area under the concentration-time curve (AUC), total and renal clearance (CL), half-life (T1/2), and volume of distribution at steady state (Vss). RESULTS: CsA concentrations more than 2,000 ng/mL produced an increase in etoposide AUC of 80% (P less than .001), a 38% decrease in total CL (P < .01), a > twofold increase in T1/2 (P < .01), and a 46% larger Vss (P = .01) compared with etoposide alone. CsA levels ranged from 297 to 5,073 ng/mL. Higher CsA levels (< 2,000 ng/mL v > 2,000 ng/mL) resulted in greater changes in etoposide kinetics: Vss (1.4% v 46%) and T1/2 (40% v 108%). CsA produced a 38% decrease in renal and a 52% decrease in nonrenal CL of etoposide. Etoposide with CsA levels > 2,000 ng/mL produced a lower WBC count nadir (900/mm3 v 1,600/mm3) compared with baseline etoposide cycles. CONCLUSIONS: High-dose CsA produces significant increases in etoposide systemic exposure and leukopenia. These pharmacokinetic changes are consistent with inhibition by CsA of the multidrug transporter P-glycoprotein in normal tissues. Etoposide doses should be reduced by 50% when used with high-dose CsA in patients with normal renal and liver function. Alterations in the disposition of other multidrug resistance (MDR)-related drugs should be expected to occur with modulation of P-glycoprotein function in clinical trials.

Weekly doxorubicin in endocrine-refractory carcinoma of the prostate.

Twenty-five patients with endocrine-refractory prostatic carcinoma were treated with doxorubicin, 20 mg/m2 given weekly. All patients had prior hormonal therapy (68% had two or more prior hormonal maneuvers), and 21 (84%) had prior therapeutic or palliative irradiation. Median Karnofsky performance status at the time of entry was 70. Hemoglobin was less than 12.0 g/dL in 15 patients. Bidimensional tumors were present in 12 patients in 19 disease sites; four of the 12 patients (33%) responded in eight of the 19 sites (42%); and three of eight patients had a 75% decrease in prostatic nodule size. Ten of 20 evaluable patients had an improvement of 20% or greater in Karnofsky performance status and 67% (14 of 21) had marked improvement in pain. A greater than 50% reduction or normalization of acid phosphatase occurred in 19% and of alkaline phosphatase in 53%. The overall response rate by National Prostatic Cancer Project criteria was 84%. Gastrointestinal toxicity and alopecia were minimal and myelosuppression was not life threatening in any patient.

Phase I trial of doxorubicin with cyclosporine as a modulator of multidrug resistance.

PURPOSE: To study the effects of cyclosporine (CsA), a modulator of multidrug resistance (MDR), on the pharmacokinetics and toxicities of doxorubicin. PATIENTS AND METHODS: Nineteen patients with incurable malignancies entered this phase I trial. Initially patients received doxorubicin alone (60 or 75 mg/m2) as a 48-hour continuous intravenous (i.v.) infusion. Patients whose tumors did not respond received CsA as a 2-hour loading dose of 6 mg/kg and a 48-hour continuous infusion of 18 mg/kg/d with doxorubicin. Target CsA levels were 3,000 to 4,800 ng/mL (2.5 to 4.0 mumol/L). Doxorubicin doses were reduced to 40% of the prior dose without CsA, and then escalated until myelosuppression equivalent to that resulting from doxorubicin alone was observed. Doxorubicin pharmacokinetics were analyzed with and without CsA. RESULTS: Thirteen patients received both doxorubicin alone and the combination of doxorubicin and CsA. Mean CsA levels were more than 2,000 ng/mL for all cycles and more than 3,000 ng/mL for 68% of cycles. Dose escalation of doxorubicin with CsA was stopped at 60% of the doxorubicin alone dose, as four of five patients at this dose level had WBC nadirs equivalent to those seen with doxorubicin alone. Nonhematologic toxicities were mild. Reversible hyperbilirubinemia occurred in 68% of doxorubicin/CsA courses. The addition of CsA to doxorubicin increased grade 1 and 2 nausea (87% v 47%) and vomiting (50% v 10%) compared with doxorubicin alone. There was no significant nephrotoxicity. Paired pharmacokinetics were studied in 12 patients. The addition of CsA increased the dose-adjusted area under the curve (AUC) of doxorubicin by 55%, and of its metabolite doxorubicinol by 350%. CONCLUSION: CsA inhibits the clearance of both doxorubicin and doxorubicinol. Equivalent myelosuppression was observed when the dose of doxorubicin with CsA was 60% of the dose of doxorubicin without CsA. Understanding these pharmacokinetic interactions is essential for the design and interpretation of clinical trials of MDR modulation, and should be studied with more potent MDR modulators.

Pharmacokinetic interactions of cyclosporine with etoposide and mitoxantrone in children with acute myeloid leukemia.

The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.

A phase I trial of doxorubicin, paclitaxel, and valspodar (PSC 833), a modulator of multidrug resistance.

PURPOSE: P-glycoprotein is an efflux pump for many drugs including doxorubicin and paclitaxel. This study evaluated the coadministration of these drugs with the P-glycoprotein inhibitor valspodar (PSC 833) with the aim of determining: (a) maximum tolerated doses (MTDs) of doxorubicin followed by paclitaxel (DP); (b) the MTD of DP combined with PSC 833 (DPV), without and with filgrastim (G-CSF); and (c) the pharmacokinetic interactions of PSC 833 with doxorubicin and paclitaxel. EXPERIMENTAL DESIGN: For the first cycle, patients received doxorubicin as a 15-min infusion followed by paclitaxel as a 1-h infusion. For the second cycle, patients received reduced doses of DP with PSC 833 at 5 mg/kg p.o., four times a day for 12 doses. RESULTS: Thirty-three patients with various refractory malignancies were enrolled and assessable. The MTD of DP without PSC 833 was 35 mg/m(2) doxorubicin and 150 mg/m(2) paclitaxel. The MTD of DPV without G-CSF was 12.5 mg/m(2) doxorubicin and 70 mg/m(2) paclitaxel. The dose-limiting toxicity for both DP and DPV was neutropenia without thrombocytopenia. With G-CSF, the MTD for DPV was 20 mg/m(2) doxorubicin and 90 mg/m(2) paclitaxel. No grade 4 nonhematological toxicities were observed. Five partial and two minor tumor remissions were observed. Paired pharmacokinetics with and without PSC 833 revealed substantial drug interactions with both doxorubicin and paclitaxel. CONCLUSIONS: PSC 833 can be administered safely with doxorubicin and paclitaxel. The pharmacokinetic profiles of these drugs are significantly affected by PSC 833, requiring approximately 60% dose reductions for equivalent degrees of myelosuppression.

A phase I single-dose trial of gadolinium texaphyrin (Gd-Tex), a tumor selective radiation sensitizer detectable by magnetic resonance imaging.

Gadolinium Texaphyrin (Gd-Tex) is a radiation sensitizer with a novel mechanism of action that sensitizes both oxic and hypoxic cells, localizes selectively in tumors, and is detectable by magnetic resonance imaging (MRI). This Phase I single-dose trial of Gd-Tex administered concurrently with radiation therapy was carried out to determine the maximally tolerated dose (MTD), dose-limiting toxicities, pharmacokinetics, and biolocalization of Gd-Tex as determined by MRI. Adults with incurable cancers of any histology requiring radiation therapy were eligible. A single i.v. dose of Gd-Tex was followed at least 2 h later by radiation therapy. The Gd-Tex dose was escalated in cohorts of 3 to 5 patients. Thirty-eight patients (median age, 58 years; range, 35-77 years) with incurable cancers of the lung (26), cervix (3), or other solid tumors (9) received a total of 41 single administrations of Gd-Tex. The Gd-Tex dose was escalated from 0.6 to 29.6 mg/kg. Irradiated sites included the thorax, brain, pelvis, bone, soft tissue, and sites of nodal metastases. The MTD was 22.3 mg/kg, determined by reversible acute tubular necrosis as the dose-limiting toxicities. Gd-Tex selectively accumulated in primary and metastatic tumors as demonstrated by MRI. No increase in radiation toxicity to normal tissues was seen. The median half-life of Gd-Tex after single-dose administration is 7.4 h. This study demonstrates that Gd-Tex is well tolerated in doses below the MTD, and that there is selective biolocalization in tumors. The maximum recommended dose for single administrations is 16.7 mg/kg.

Therapeutic approaches including interferon to carcinoma in situ of the bladder.

The management of CIS of the bladder consists of two complementary but separate therapeutic goals: treatment of existing disease and the prevention of recurrence. At present the biological behavior and prognosis of CIS remains to be completely defined. To date, the majority of experience with the medical management of CIS of the bladder is with chemotherapeutic agent doxorubicin and the immunotherapeutic agent BCG. Other agents such as mitomycin and interferon appear promising. The efficacy of these drugs will have to be evaluated in prospective randomized trials. At that time a number of questions should be answered concerning the treatment of CIS of the bladder: what is the effect of these agents on morbidity and survival, what is the optimal dose, schedule, and duration of therapy for these drugs, and will the biology of the disease, e.g. extravesical recurrences mandate systemic therapy?

Superficial carcinoma of the bladder: natural history and the role of interferons.

Superficial transitional cell carcinoma of the bladder is a chronic disease. Patients face a lifetime with the potential for further neoplastic manifestations--the recurrence of either superficial or deeply invasive tumor. To some extent, the likelihood of disease recurrence can be predicted. Further, certain clinical interventions can alter the probability of tumor recurrence. This paper focuses on those patient and tumor characteristics that predict for the propensity to develop recurrent disease, with emphasis on the potential of the interferons to both treat this disease and to modify its natural history.

Long-term results of irradiation for patients with progressive Graves' ophthalmopathy.

PURPOSE: To determine the long-term outcome of radiotherapy (RT) in patients with progressively symptomatic thyroid eye disease and to evaluate the potential long-term sequelae. METHODS AND MATERIALS: Four hundred fifty-three patients provided written informed consent and received retrobulbar RT for Graves' ophthalmopathy at Stanford University Medical Center; 197 with 1 year of follow-up were retrospectively analyzed. Of the 197 patients, 189 received RT to the bilateral retrobulbar regions, and 4 received unilateral RT. The technical information was unavailable for 4 patients. Patients were assessed by chart review, telephone interview, questionnaire, and multidisciplinary physician examination. Eye impairment was scored using the SPECS system. The end point review included the before and after treatment SPECS score, surgical intervention, and patient satisfaction. Potential complications, including cataract development, retinopathy, and tumor formation, were investigated. Multivariate analyses were performed to assess the prognostic variables. RESULTS: Improvement or resolution was 89% for soft-tissue findings; 70% for proptosis; 85% for extraocular muscle dysfunction; 96% for corneal abnormalities; and 67% for sight loss. The response to RT may take >6 months to stabilize. Factors predictive of response varied in the individual SPECS categories but included the initial SPECS score, pretreatment thyroid status, female gender, a 20-Gy RT dose, and a history of hypertension. Nonpredictive factors included a history of tobacco use, diabetes mellitus, steroids, and prior cataracts. Only 16% required surgical intervention to preserve their vision or restore binocular vision. Twenty-two patients (12%) developed cataracts after irradiation (median 11 years). No patient developed a tumor within the RT field during the follow-up period (range 1-29 years). Ninety-eight percent of patients were pleased with their results, and 2% believed their symptoms progressed despite RT. CONCLUSIONS: Retrobulbar irradiation (20 Gy) is safe and effective treatment for progressive Graves' ophthalmopathy, with a 96% overall response rate, 98% patient satisfaction rate, and no irreparable long-term sequelae, with follow-up extending 29 years. The most common late effect observed was cataract development, which occurred more frequently in older patients and was reversible with extraction. Elective surgical intervention after RT should be withheld until patients have demonstrated a plateau in response.

The impact of body weight on cyclosporine pharmacokinetics in renal transplant recipients.

In order to assess the effect of body weight on cyclosporine disposition, 45 adult uremic candidates for renal transplantation underwent detailed nutritional assessment and pharmacokinetic analysis. There were 10 obese and 35 nonobese patients defined as actual body weight (ABW) greater than 125 Per cent of ideal body weight (IBW), and arm fat area greater than 90th percentile. There was no significant difference in demographic variables such as age, sex, number of diabetics, IBW, serum lipids, or liver function tests between the 2 groups. Although there was a significant difference in ABW, pharmacokinetic analyses failed to demonstrate significant differences in bioavailability, elimination half-life, clearance, or apparent steady state volume of distribution when these calculations were normalized by IBW, body surface area, or as absolute values. Multiple stepwise linear regression failed to demonstrate a significant correlation between serum lipids or body size measurements and these parameters. When dosed according to ABW, obese recipients of renal allografts had a mean serum RIA trough level of 227 ng/ml as compared to 121 ng/ml in nonobese recipients on day 7. Therefore in order to achieve comparable drug concentrations in the early transplant period, CsA should be given to obese patients based on their IBW.

Absolute bioavailability and absorption characteristics of aerosolized tobramycin in adults with cystic fibrosis.

Administration of antibiotics by the inhalational route has become part of standard protocols for treatment of and prophylaxis for Pseudomonal pneumonias in patients with cystic fibrosis. For tobramycin, however, limited data are available on the aerosol absorption patterns, and no absolute bioavailability data for tobramycin exist. The purpose of this study was to measure the absolute bioavailability and systemic absorption characteristics of tobramycin when administered in high doses by a nebulizer. Multiple serum concentrations of tobramycin were measured after administration of an intravenous dose (mean, 2.9 mg/kg every 6 hours) and after an inhalational dose (5.6 mg/kg over 1 hour). Inhalational doses were superimposed over the "tail" of a steady-state intravenous dose to improve the sensitivity of the assay procedure (Abbott-TDX). Absolute bioavailability (F) was determined from AUC ratios normalized for dose. Model-independent pharmacokinetic parameters (volume of distribution [Vss] and total clearance [CLt]) were determined for each subject. Absorption characteristics (absorption rate constant [Ka] and mean absorption time [MAT]) were assessed after calculation of the cumulative fraction of drug absorbed, amount of bioavailable drug, and percent remaining to be absorbed per unit time using the Loo-Riegelman method. Three men and three women completed the study, and all received concurrent doses of ceftazidime. Mean absolute bioavailability (+/- standard deviation) was 9.13% (+/- 3.82), and the rate of absorption into the systemic circulation was consistent with a zero-order model profile for all subjects. Mean absorption time values reflected a wide degree of subject variability and ranged from approximately 15 to 150 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)