Pharmacokinetics and the effect of application site on a novel, long-acting transdermal fentanyl solution in healthy laboratory Beagles.

Application of transdermal drugs to different anatomical sites can result in different absorption characteristics. The pharmacokinetics (PKs) and bioequivalence of a single 2.6 mg/kg (50 µL/kg) dose of a novel, long-acting transdermal fentanyl solution were determined when applied topically to the ventral abdominal or dorsal interscapular skin of 40 healthy laboratory Beagles. The PKs were differentiated by a more rapid initial absorption of fentanyl from the dorsal application site. Mean plasma fentanyl concentrations remained above 0.6 ng/mL from 4 to 96 h in the dorsal application group and from 8 to 144 h in the ventral application group. Bioequivalence analysis demonstrated that the sites were not equivalent; the 90% confidence intervals of the ratio of the geometric means for both the maximum concentration (C(max)) and the area under the curve (AUC) were not contained within the 80-125% interval. The C(max) was 2.34 ± 1.29 (mean ± standard deviation) and 2.02 ± 0.84 ng/mL for the ventral and dorsal application groups, respectively. The terminal elimination half-lives (t(1/2)) for both groups were similar with values of 137 ± 58.9 and 117 ± 59.6 h for the ventral and dorsal application site groups, respectively. A mean absorption rate of ≥ 2 µg · kg/h was maintained from 2 to 144 h following dorsal application and from 2 to 264 h following ventral application. These results suggest that transdermal fentanyl solution could be applied as a single dose to the dorsal scapular area 2-4 h prior to surgery with analgesia lasting a minimum of 4 days.

Naloxone reversal of an overdose of a novel, long-acting transdermal fentanyl solution in laboratory Beagles.

Opioid overdose in dogs is manifested by clinical signs such as excessive sedation, bradycardia, and hypothermia. The ability of two different intramuscular (i.m.) naloxone reversal regimens to reverse the opioid-induced effects of a fivefold overdose of long-acting transdermal fentanyl solution was evaluated in dogs. Twenty-four healthy Beagles were administered a single 13 mg/kg dose (fivefold overdose) of transdermal fentanyl solution and randomized to two naloxone reversal regimen treatment groups, hourly administration for 8 h of 40 (n = 8) or 160 µg/kg i.m. (n = 16). All dogs were sedated and had reduced body temperatures and heart rates (HRs) prior to naloxone administration. Both dosage regimens significantly reduced sedation (P < 0.001), and the 160 µg/kg naloxone regimen resulted in a nearly threefold lower odds of sedation than that of the 40 µg/kg i.m. naloxone regimen (P < 0.05). Additionally, naloxone significantly increased the mean body temperatures and HR (P < 0.001), although the 160 µg/kg regimen increased body temperature and HR more (P < 0.05). However, the narcotic side effects of fentanyl returned within 1-3 h following termination of the naloxone dosage regimens. The opioid-induced effects of an overdose of transdermal fentanyl solution can be safely and effectively reversed by either 40 or 160 µg/kg i.m. naloxone administered at hourly intervals.

Population pharmacokinetics of transdermal fentanyl solution following a single dose administered prior to soft tissue and orthopedic surgery in dogs.

A novel, long-acting transdermal fentanyl solution (TFS) that delivers sustained plasma fentanyl concentrations following a single application for the control of postoperative pain has recently been approved for use in dogs. The pharmacokinetics (PKs) of this formulation have been evaluated in healthy laboratory dogs, but they have not been reported in a clinical population of dogs for which it is indicated. Plasma fentanyl concentrations were determined from 215 dogs following a single, small-volume (∼50 µL/kg) dose of TFS administered 2-4 h prior to orthopedic or soft tissue surgery. A population PK model was fit, and a 1-compartment open PK model with first-order absorption and an absorption lag-time best described the data. No tested clinical covariates had a significant effect on the PKs. The final model adequately described the population PKs and gave results consistent with laboratory PK studies in healthy dogs. The PKs were primarily characterized by a rapid initial increase in plasma fentanyl concentrations and a long terminal half-life of 74.0 (95% C.I. [54.7-113]) h governed by flip-flop kinetics for the typical subject. The plasma fentanyl concentrations were sustained over days in the range considered to be analgesic for postoperative pain in dogs.

The effect of inhibiting topoisomerase I and II on the anti-apoptotic response associated with pro-inflammatory crystals of calcium pyrophosphate dihydrate in human neutrophils.

OBJECTIVE AND DESIGN: To investigate the ability of various topoisomerase I and II inhibitors to reverse the pro-survival effects of calcium pyrophosphate dihydrate (CPPD) crystals on human neutrophils, thereby identifying potential agents that may promote the resolution of neutrophil accumulation typical of crystal associated inflammatory diseases. MATERIALS AND METHODS: Freshly isolated human neutrophils incubated in the presence of CPPD crystals, with or without the pro-apoptotic cytokine TNF-alpha, were pre-incubated in the presence or absence of the topoisomerase I inhibitors camptothecin, nogalamycin or beta-lapachone, or topoisomerase II inhibitors etoposide, doxorubicin or mitoxantrone. Neutrophil respiratory burst was assessed via chemiluminescence, and two quantitative methods were used for the determination of neutrophil apoptosis; cytoplasmic histone-associated-DNA fragmentation assessment, and endogenous caspase 3 substrate (Ac-DEVD-AMC) cleavage. RESULTS: Beta-lapachone and mitoxantrone effectively repressed CPPD crystal associated respiratory burst, whereas the other topoisomerase inhibitors had no inhibitory or stimulatory effect. Camptothecin and all of the topoisomerase II inhibitors induced neutrophil apoptosis, even in the presence of the CPPD crystals that normally repress TNF-alpha-induced and spontaneous apoptosis. CONCLUSIONS: These results suggest that although topoisomerase II antagonists are distinctively effective agents at reversing the pro-survival effects of crystals on neutrophils, camptothecin was unique as a topoisomerase I inhibitor in that it was significantly more effective as a pro-apoptosis inducer than the topoisomerase II poisons without affecting normal neutrophil activation responses.

The involvement of phospholipase C in crystal induced human neutrophil activation.

OBJECTIVE: To investigate the involvement of phospholipase C (PLC) in the signal transduction pathway leading to neutrophil activation by inflammatory microcrystals. METHODS: Neutrophil chemiluminescence, superoxide anion generation, and degranulation responses to opsonized crystals were measured in the presence of U73122, a specific inhibitor of PLC. Phospholipase Cgamma2 (PLCgamma2) activity was measured by Western blotting. RESULTS: U73122 was shown to inhibit neutrophil activation induced by plasma opsonized crystals of calcium pyrophosphate dihydrate (CPPD) and monosodium urate monohydrate. The IC50 for inhibition of crystal induced respiratory burst (measured by chemiluminescence) was roughly 3 microM. No inhibition of crystal induced respiratory burst was observed using U73343, an inactive analog of U73122. These results show the pivotal role of PLC in neutrophil respiratory burst activation by both crystals. Superoxide anion generation and degranulation responses of neutrophils to CPPD crystals were also strongly inhibited by U73122 at a concentration of 10 microM, supporting the concept of direct involvement of PLC in signal transduction pathways leading to crystal induced oxidase activation and degranulation responses. CPPD crystals caused a sustained increase in the tyrosine phosphorylation levels of PLCgamma2 in neutrophils. CONCLUSION: We conclude that PLC plays a central role in signal transduction pathways leading to respiratory burst and degranulation responses in neutrophils activated by inflammatory microcrystals, and that PLCgamma2 may be the isoform involved in these pathways.

Inhibition of TNF-alpha-induced neutrophil apoptosis by crystals of calcium pyrophosphate dihydrate is mediated by the extracellular signal-regulated kinase and phosphatidylinositol 3-kinase/Akt pathways up-stream of caspase 3.

The role of protein kinases in the inhibition of TNF-alpha associated apoptosis of human neutrophils by crystals of calcium pyrophosphate dihydrate (CPPD) (25 mg/ml) was investigated. We monitored the activities of the p44 extracellular signal-regulated kinase 1 (ERK1) and p42 ERK2 mitogen-activated protein (MAP) kinases and phosphatidylinositol 3-kinase (PI3-K)-regulated protein kinase B (Akt) in neutrophils incubated with TNF-alpha and CPPD crystals, separately and in combination, in parallel with the endogenous caspase 3 activity and DNA fragmentation. CPPD crystals were observed to induce a robust and transient activation of ERK1, ERK2, and Akt, whereas TNF-alpha produced only a modest and delayed activation of Akt. In the presence of TNF-alpha, Akt activity was enhanced, and CPPD crystal-induced activation of ERK1 and ERK2 was more sustained than with CPPD crystals alone, but TNF-alpha itself reduced the basal phosphotransferase activities of these MAP kinases. Preincubation with the MAP kinase kinase (MEK1) inhibitors PD98059 (20 ng/ml) and U0126 (250 nM), or the PI3-K inhibitors wortmannin (100 nM) and LY294002 (50 microM) repressed the activation of ERK1, ERK2, and Akt in association with CPPD crystal incubation, in the absence or presence of TNF-alpha. Furthermore, the inhibition of the Mek1/Mek2-->ERK1/ERK2 or PI3-K/Akt pathways reversed CPPD crystal-associated suppression of TNF-alpha-induced caspase 3 activation and neutrophil apoptosis. Together, these results indicate that CPPD crystals function to induce acute inflammatory responses through ERK1/ERK2 and PI3-K/Akt-mediated stimulation of neutrophil activation and repression of apoptosis.

The inhibition of spontaneous and tumor necrosis factor-alpha induced neutrophil apoptosis by crystals of calcium pyrophosphate dihydrate and monosodium urate monohydrate.

OBJECTIVE: Spontaneous neutrophil apoptosis may be inhibited by various proinflammatory stimuli. which may result in prolonged lifetimes and responses of these phagocytic cells with the potential for extended inflammation. We investigated the effect of short term incubation of opsonized crystals of monosodium urate monohydrate (MSUM) or calcium pyrophosphate dihydrate (CPPD) on both spontaneous and tumor necrosis factor-alpha (TNF-alpha) induced neutrophil apoptosis. METHODS: Peripheral neutrophils were incubated with plasma opsonized crystals of CPPD or MSUM in the presence or absence of TNF-alpha for 4 h at 37 degrees C. Apoptosis was determined using 3 separate assays: (1) an agarose DNA fragmentation assay, (2) a cytoplasmic histone associated DNA fragmentation assay, and (3) a caspase 3 fluorometric assay. RESULTS: All 3 assays showed similar results. Both MSUM and CPPD crystals inhibited spontaneous apoptosis in neutrophils. TNF-alpha induced high levels of apoptosis in neutrophils. However, co-incubation of the cells with TNF-alpha and crystals resulted in the inhibition of apoptosis to levels below those of control cells. Pretreatment of neutrophils with the protein synthesis inhibitor cycloheximide prevented the inhibition of apoptosis by crystals. CONCLUSION: These data support the concept of crystal induced inhibition of neutrophil apoptosis as part of the pathophysiology of the diseases collectively known as crystal induced arthritis.

Selective inhibition of protein kinase C, mitogen-activated protein kinase, and neutrophil activation in response to calcium pyrophosphate dihydrate crystals, formyl-methionyl-leucyl-phenylalanine, and phorbol ester by O-(chloroacetyl-carbamoyl) fumagillol (AGM-1470; TNP-470).

The effect of O-(chloroacetyl-carbamoyl) fumagillol (AGM-1470; TNP-470) was investigated on protein kinase C (PKC) and mitogen-activated protein kinase (MAPK) activation in neutrophils stimulated by plasma-opsonized crystals of calcium pyrophosphate dihydrate (triclinic) [CPPD(T)], formyl-Met-Leu-Phe (fMLP), and phorbol 12-myristate 13-acetate (PMA). Neutrophil respiratory burst responses also were determined in AGM-1470-pretreated cells stimulated with the same agonists, using chemiluminescence and superoxide anion generation assays. AGM-1470 (5 microM) effectively inhibited PKC activation in cells treated with CPPD(T) crystals (50 mg/mL, 2 min) and fMLP (1 microM, 1 min), but had no effect on PMA-treated cells (0.5 microM, 5 min). AGM-1470 blocked MAPK activity completely and reduced neutrophil activation induced by fMLP and PMA but not by CPPD(T). The degree of inhibition of the respiratory burst plateaued at approximately 46+/-9 and 54+/-3% in fMLP- and PMA-treated cells, respectively. These data indicate that activation of neutrophil respiratory burst activity may be mediated through the MAPK pathway. AGM-1470 pretreatment did not inhibit CPPD(T) crystal- or fMLP-stimulated phosphatidylinositol 3-kinase (PI 3-kinase) activity. These findings, coupled with further observations that the PI 3-kinase inhibitor wortmannin (10 nM) inhibited fMLP- and CPPD(T) crystal-induced but not PMA-induced chemiluminescence, indicate that at least two distinct signaling pathways (mediated by PI 3-kinase or MAPK) lead to neutrophil respiratory burst responses. PKC may also be required in the MAPK-stimulated pathway. We propose that the inhibitory effect of AGM-1470 on the neutrophil respiratory burst may be due to its ability to inhibit PKC and MAPK activation.

Depolarization and neurotrophins converge on the phosphatidylinositol 3-kinase-Akt pathway to synergistically regulate neuronal survival.

In this report, we have examined the mechanisms whereby neurotrophins and neural activity coordinately regulate neuronal survival, focussing on sympathetic neurons, which require target-derived NGF and neural activity for survival during development. When sympathetic neurons were maintained in suboptimal concentrations of NGF, coincident depolarization with concentrations of KCl that on their own had no survival effect, synergistically enhanced survival. Biochemical analysis revealed that depolarization was sufficient to activate a Ras-phosphatidylinositol 3-kinase-Akt pathway (Ras-PI3-kinase-Akt), and function-blocking experiments using recombinant adenovirus indicated that this pathway was essential for approximately 50% of depolarization-mediated neuronal survival. At concentrations of NGF and KCl that promoted synergistic survival, these two stimuli converged to promote increased PI3-kinase-dependent Akt phosphorylation. This convergent PI3-kinase-Akt pathway was essential for synergistic survival. In contrast, inhibition of calcium/calmodulin-dependent protein kinase II revealed that, while this molecule was essential for depolarization-induced survival, it had no role in KCl- induced Akt phosphorylation, nor was it important for synergistic survival by NGF and KCl. Thus, NGF and depolarization together mediate survival of sympathetic neurons via intracellular convergence on a Ras-PI3-kinase-Akt pathway. This convergent regulation of Akt may provide a general mechanism for coordinating the effects of growth factors and neural activity on neuronal survival throughout the nervous system.

Activation of S6 kinase in human neutrophils by calcium pyrophosphate dihydrate crystals: protein kinase C-dependent and phosphatidylinositol-3-kinase-independent pathways.

Phosphatidylinositol 3-kinase (PI 3-kinase) has been shown previously to be a central enzyme in crystal-induced neutrophil activation. Since activation of the 70 kDa S6 kinase (p70S6K) has been shown to be dependent on PI 3-kinase activation in mammalian cells, and since the former is a key enzyme in the transmission of signals to the cell nucleus, activation of p70(S6K) was investigated in crystal-stimulated neutrophils. Cytosolic fractions from calcium pyrophosphate dihydrate (CPPD)-crystal-activated neutrophils were separated by Mono Q chromatography and analysed for phosphotransferase activity using a range of substrates and probed by Western analysis using antibodies to p70(S6K) and mitogen-activated protein kinase (MAP kinase). CPPD crystals induced a robust, transient activation (peak activity at 2 min) of p70(S6K) that was fully inhibited by pretreatment with rapamycin. This is the first report of the activation of p70(S6K) in neutrophil signal transduction pathways induced by an agonist. This crystal-induced activation of p70(S6K) could also be inhibited by a protein kinase C (PKC) inhibitor (Compound 3), but not by the PI 3-kinase inhibitor wortmannin. CPPD crystals also activated the ERK1 and ERK2 forms of MAP kinase (wortmannin insensitive), PKC (Compound 3 sensitive) and protein kinase B (wortmannin sensitive) in neutrophils. These data suggest that activation of p70(S6K) may proceed through a PI 3-kinase- and protein kinase B-independent but PKC-dependent pathway in crystal-activated neutrophils.

Calcium pyrophosphate dihydrate crystals activate MAP kinase in human neutrophils: inhibition of MAP kinase, oxidase activation and degranulation responses of neutrophils by taxol.

The activation of MAP kinase in human neutrophils stimulated by both uncoated and plasma-opsonized crystals of triclinic calcium pyrophosphate dihydrate (CPPD) was investigated. The effect of taxol on MAP kinase activation and on the responses of neutrophils stimulated by plasma-opsonized crystals was determined. MAP kinase activation was identified and quantified in Mono Q chromatography separated fractions of neutrophils that had been incubated with CPPD crystals by measuring [gamma-32P]adenosine triphosphate (ATP) phosphorylation of myelin basic protein and using immunoblotting techniques. Human neutrophils were incubated with taxol (0-50 microM), added to plasma-opsonized CPPD (50 mg/ml) and MAP kinase activation, chemiluminescence, superoxide anion generation, lysozyme and myeloperoxidase release were monitored. Both uncoated and plasma coated CPPD crystals induced a large increase in MAP kinase activity in neutrophils over control levels within 1 min of incubation. Pretreatment of neutrophils with taxol was able to suppress this activation of MAP kinase. Taxol produced a concentration-dependent inhibition of opsonized CPPD-induced neutrophil chemiluminescence, superoxide anion production and myeloperoxide release. Taxol at 28 microM also significantly inhibited chemiluminescence, superoxide anion production and myeloperoxidase release from neutrophils stimulated by opsonized zymosan. This is the first report of crystal-induced activation of MAP kinase in neutrophils. Microtubule-associated processes, such as signal transduction, secretion and phagocytosis are involved in particulate-induced neutrophil responses. We have suggested that the inhibitory effect of taxol observed in this work is due to its stabilizing effect on microtubules and disruption of MAP kinase activation associated with microtubules.

Chromosome condensation induced by fostriecin does not require p34cdc2 kinase activity and histone H1 hyperphosphorylation, but is associated with enhanced histone H2A and H3 phosphorylation.

Chromosome condensation at mitosis correlates with the activation of p34cdc2 kinase, the hyperphosphorylation of histone H1 and the phosphorylation of histone H3. Chromosome condensation can also be induced by treating interphase cells with the protein phosphatase 1 and 2A inhibitors okadaic acid and fostriecin. Mouse mammary tumour FT210 cells grow normally at 32 degrees C, but at 39 degrees C they lose p34cdc2 kinase activity and arrest in G2 because of a temperature-sensitive lesion in the cdc2 gene. The treatment of these G2-arrested FT210 cells with fostriecin or okadaic acid resulted in full chromosome condensation in the absence of p34cdc2 kinase activity or histone H1 hyperphosphorylation. However, phosphorylation of histones H2A and H3 was strongly stimulated, partly through inhibition of histone H2A and H3 phosphatases, and cyclins A and B were degraded. The cells were unable to complete mitosis and divide. In the presence of the protein kinase inhibitor starosporine, the addition of fostriecin did not induce histone phosphorylation and chromosome condensation. The results show that chromosome condensation can take place without either the histone H1 hyperphosphorylation or the p34cdc2 kinase activity normally associated with mitosis, although it requires a staurosporine-sensitive protein kinase activity. The results further suggest that protein phosphatases 1 and 2A may be important in regulating chromosome condensation by restricting the level of histone phosphorylation during interphase, thereby preventing premature chromosome condensation.

Antitumor drug fostriecin inhibits the mitotic entry checkpoint and protein phosphatases 1 and 2A.

In most eukaryotic cells, entry into mitosis is tightly controlled and requires completely replicated and undamaged DNA. We show that the antitumor drug, fostricin, interferes with this control; it induces cycling cells to enter mitosis prematurely, and it can overcome the mitotic entry checkpoint, forcing into mitosis cells that were arrested in the division cycle by treatment with the DNA replication inhibitor aphidicolin or with the DNA-damaging agents camptothecin and teniposide. This effect was observed in all rodent, simian, and human cell lines tested. Fostriecin also hampers progression through the later stages of mitosis as determined by the absence of normal half-spindles, anaphase figures, and telophase figures. The only previously known target for fostriecin is topoisomerase II, which is inhibited in vitro with a 50% inhibitory concentration of 40 microM (T. J. Boritzki, T. S. Wolfard, J. A. Besserer, R. C. Jackson, and D. W. Fry. Inhibition of type II topoisomerase by fostriecin. Biochem. Pharmacol., 37: 4063-4068, 1988). We show that fostriecin is a more potent inhibitor of protein phosphatase 1, with a 50% inhibitory concentration of 4 microM and protein phosphatase 2A, with a 50% inhibitory concentration of 40 nM. Inhibition of the mitotic entry checkpoint and inhibition of protein phosphatases are novel properties for antitumor drugs with potential or proven therapeutic value.