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Objective: Human regular U-500 (U-500R) insulin (500 units/mL) is increasingly being used clinically, yet its pharmacokinetics (PK) and pharmacodynamics (PD) have not been well studied. Therefore, we compared PK and PD of clinically relevant doses of U-500R with the same doses of human regular U-100 (U-100R) insulin (100 units/mL).Research Design and Methods: This was a single-site, randomized, double-blind, crossover euglycemic clamp study. Single subcutaneous injections of 50- and 100-unit doses of U-500R and U-100R were administered to 24 healthy obese subjects.Results: Both overall insulin exposure (area under the serum insulin concentration versus time curve from zero to return to baseline [AUC(0-)(t)(')]) and overall effect (total glucose infused during a clamp) were similar between formulations at both 50- and 100-unit doses (90% [CI] of ratios contained within [0.80, 1.25]). However, peak concentration and effect were significantly lower for U-500R at both doses (P < 0.05). Both formulations produced relatively long durations of action (18.3 to 21.5 h). Time-to-peak concentration and time to maximum effect were significantly longer for U-500R than U-100R at the 100-unit dose (P < 0.05). Time variables reflective of duration of action (late tR(max50), tR(last)) were prolonged for U-500R versus U-100R at both doses (P < 0.05).Conclusions: Overall exposure to and action of U-500R insulin after subcutaneous injection were no different from those of U-100R insulin. For U-500R, peaks of concentration and action profiles were blunted and the effect after the peak was prolonged. These findings may help guide therapy with U-500R insulin for highly insulin-resistant patients with diabetes. [ABSTRACT FROM AUTHOR]

Objectives: This study sought to describe in detail the pharmacokinetics and pharmacodynamics of chimeric monoclonal 7E3 Fab (c7E3 Fab) and to compare platelet responses to adenosine diphosphate (ADP) and the 11-amino acid thrombin receptor-activating peptide (TRAP [SFLLRNPNDKY-NH2]) in patients undergoing elective coronary angioplasty., Background: Inhibition of platelet aggregation with monoclonal antibody c7E3 Fab directed against glycoprotein (GP) IIb/IIIa has been shown to reduce ischemic complications after angioplasty and is being considered for treatment of other acute ischemic syndromes., Methods: Patients undergoing elective coronary angioplasty received aspirin (325 mg orally), heparin (12,000 U intravenously) and a bolus of c7E3 Fab (0.25 mg/kg body weight). Surface GPIIb/IIIa receptor blockade and aggregation in response to 20 mumol/liter ADP, 5 micrograms/ml collagen and 7.5 and 15 mumol/liter TRAP were assessed., Results: Surface GPIIb/IIIa receptor blockade by c7E3 Fab was 80% 2 h after injection and decreased to 50% at 24 h. Platelet aggregation in response to 20 mumol/liter ADP was inhibited by 73% at 2 h, and this inhibition decreased to 27% at 24 h. Platelet aggregation in response to 7.5 mumol/liter TRAP was inhibited by 53% at 2 h and 30% at 24 h. In contrast, aggregation in response to 15 mumol/liter TRAP was inhibited only 37% at 2 h and 10% at 24 h (p < 0.001 and p = 0.006, respectively vs. 20 mumol/liter ADP). Addition of exogenous c7E3 Fab to platelet-rich plasma led to more complete inhibition of 7.5 mumol/liter TRAP-induced aggregation., Conclusions: After c7E3 Fab treatment, inhibition of platelet aggregation depends on the agonist and can be overcome by increased thrombin activity but is restored if additional c7E3 Fab is added to block additional GPIIb/IIIa receptors. This phenomenon may be related to an internal pool of GPIIb/IIIa receptors joining the surface membrane and has implications concerning the duration of therapy with c7E3 Fab for patients with unstable angina or acute myocardial infarction.

Using the C57BL/6/EL4 tumor model, studies were carried out to demonstrate the feasibility of administering Adriamycin (ADM) in therapeutic doses and schedules such that the host antitumor defenses would not be suppressed and in some cases might be stimulated by treatment. ADM treatment caused prolongation of survival and, in general, either stimulated host cytolytic activities above untreated control levels or had no effect. These effects by ADM were observed with the ADM-sensitive parent EL4 line as well as with an ADM-resistant subline, indicating that the effects did not result entirely from direct antitumor activity. The cytolytic activities examined were those of cytolytic T-lymphocytes, lymphokine-activated killer cells, and splenic and peritoneal macrophages. All activities were assessed against the syngeneic EL4 target line. The information obtained in this investigation provides a rational basis for the future development of curative protocols with ADM plus biological response modifiers, which would depend on a functional immune system for optimum efficacy and would also exploit synergistic immunomodulating effects of the agents used in combination.

The investigational chemotherapeutic drug flavone acetic acid (FAA) acts as an immunomodulator by augmenting natural killer activity in both humans and rodents after in vivo administration. The accumulated data derived from a series of experiments also demonstrates that FAA synergizes with interleukin 2 (IL-2) for the treatment of murine renal cancer. The immunomodulatory and immunotherapeutic effects of FAA are strictly dose dependent with doses of FAA greater than 150 mg/kg effectively synergizing with IL-2, and doses less than 150 mg/kg exhibiting very little therapeutic effect. The antitumor and immunomodulatory effects of FAA are more pronounced in vivo than in vitro. Collectively, these results suggested that cytokines induced by FAA may contribute to these effects, and that the induction of such cytokines may also be very dose dependent. Studies were therefore initiated to investigate whether the in vivo administration of FAA would alter the expression of cytokine mRNA in leukocytes. Splenic leukocytes or liver nonparenchymal cells from untreated and FAA-treated mice were used as a source of RNA for Northern blot analysis. Interferon alpha and interferon gamma mRNA in the spleen was upregulated within 1.5 h after FAA administration, with peak induction occurring by about 2 h. An upregulation of tumor necrosis factor alpha mRNA was detected in the spleen by 0.5-1 h after treatment with peak induction occurring by 1-1.5 h. Induction of tumor necrosis factor alpha mRNA was also detected in hepatic nonparenchymal cells. No up-regulation of splenic mRNA for tumor necrosis factor beta, IL-1 alpha or beta, or IL-2 was detected after FAA administration. IFN and TNF activities were detectable in the serum by bioassay immediately following the appearance of mRNA in FAA mice. The observed up-regulation by FAA of cytokine mRNA and the corresponding serum protein was strictly dose dependent with substantial induction of both mRNA and proteins occurring only at FAA doses greater than or equal to 150 mg/kg, a dose range also shown to be the minimum required for immunomodulatory and immunotherapeutic effects. In summary, these results demonstrate that FAA acts as a potent inducer of at least three cytokines in vivo, and suggest that the immunomodulatory and immunotherapeutic effects of FAA may be partially mediated by these induced cytokines.

Tumor necrosis factor (TNF)-sensitive (LM) and -insensitive (P815) target cell lines were used to examine the role of TNF in both the activation and lytic phases of macrophage-mediated lysis. LM cells were lysed spontaneously by thioglycolate-elicited macrophages in an 18-h assay (media or activating agents added with targets) or 36-h assay (macrophages cultured with media or activating agents for 18 h, washed, and targets added for a subsequent 18 h). In contrast, P815 cells were lysed only in the 36-h assay by macrophages exposed to appropriate activation signals. Using antibody to murine TNF, it was shown that lysis of LM cells but not P815 cells was TNF mediated. The addition of lipopolysaccharide (LPS) to the 18-h assay resulted in augmented LM killing. This was probably due to the fact that LPS stimulates macrophages to produce TNF. Conversely, when macrophages were pretreated with LPS for 18 h, washed, and assessed for lytic activity during the subsequent 18 h, lysis of LM cells was reduced relative to the endogenous level. Although macrophage lysis of P815 was not mediated by TNF, the addition of TNF to macrophage activation cultures facilitated LPS triggering of cytolytic activity against P815. Similarly, the addition of TNF to the activation cultures partially prevented the LPS-induced reduction in macrophage-mediated LM cell lysis. Taken together, these data suggest that TNF may act as an autocrine signal during macrophage activation, in addition to being directly lytic to a select number of sensitive target cell lines.

The EL4 lymphoma in C57BL/6 mice was used as a model to examine the effect of progressive tumor growth on a variety of cell mediated cytolytic effector functions which have been shown in other systems to have antitumor potential. The functions examined were those of cytolytic T-lymphocyte, lymphokine activated killer cells, natural killer cells, and tumoricidal macrophage (MO). The kinetics of each function displayed a unique pattern as a consequence of tumor growth, but all were inhibited in animals bearing large tumors (late tumor bearers). In cell mixing experiments it was shown that spleen cells from individual late tumor bearers were suppressive for cytotoxic T-lymphocytes, lymphokine activated killer cells, and splenic MO but not peritoneal MO or splenic natural killer cells. The suppression was nonspecific and was mediated primarily by nonadherent cells and/or their soluble products. Suppression appeared to be mediated, in part, by tumor cells in the spleen since the degree of suppressor activity associated with a particular spleen cell preparation correlated with the number of tumor cells present. Furthermore, the direct addition of viable ascites EL4 cells to response cultures or assays had similar suppressive effects as late TBM spleen cells, i.e., inhibited cytotoxic T-lymphocytes, lymphokine activated killer cells, and splenic MO but had no effect on natural killer cells or peritoneal MO. The mechanism of suppression by ascites EL4 was not determined but it was mediated by viable cells only and not due to contaminating viruses or other microorganisms.