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J R Kroep

Publications and source records attributed to J R Kroep.

At least 19 recordsLinked to original sources
PubMed2006

[Long-term beneficial effects of cetuximab in a woman with metastasised rectal carcinoma without expression of the epidermal growth factor receptor].

A 37-year-old woman presented with an epidermal growth factor-(EGFR)-negative rectum carcinoma with liver metastases. After extensive treatment, consisting of first-line chemotherapy, low anterior resection, isolated liver perfusion, second- and third-line chemotherapy and a pericardiodesis with bleomycin, she was subsequently treated with combination irinotecan and cetuximab therapy. At her last follow-up she had had long-term stable disease for 18 months with clinical benefit. Cetuximab is a monoclonal antibody which targets EGFRR. This exceptional case illustrates that treatment with cetuximab may be of benefit to a patient with EGFR-negative colorectal cancer. The exact mechanism of action and the role ofcetuximab in the treatment of advanced colorectal cancer have still to be determined.

Adult↗
PubMed2006

Pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin, and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer.

PURPOSE: To compare the pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Twenty-four chemo-naive patients with advanced NSCLC were randomized to receive one of the three regimens. Plasma pharmacokinetics and pharmacologic parameters in mononuclear cells were compared and related to toxicity and efficacy. RESULTS: Pharmacological parameters of gemcitabine and cisplatin were not influenced by the combination with one of the other agents, while the paclitaxel clearance was significantly lower for the combination with cisplatin as compared to gemcitabine (P=0.024). The percentage decrease in platelets was significantly higher for the gemcitabine combinations (P=0.004) and related to the dFdCTP-Cmax (P=0.030). Pharmacologic parameters were not related to response or survival. CONCLUSIONS: Gemcitabine and cisplatin pharmacology were not influenced by the combination with one of the other agents, while paclitaxel has a lower clearance in combination with cisplatin as compared to gemcitabine.

Adult↗
PubMed2005

No evidence of gemcitabine accumulation during weekly administration.

Some anticancer agents tend to accumulate during repeated administration. We determined whether gemcitabine or its metabolites would accumulate during repeated administration. Gemcitabine was administered over two courses with each course consisting of a 30-min infusion at 1000 mg/m(2) weekly for 3 weeks followed by 1 week of rest. In 14 patients we evaluated eventual accumulation by comparing the concentrations in blood samples taken before, and at 30 and 60 min after the start of infusion on days 1, 8 and 15, in both cycles. At the end of the infusion gemcitabine concentrations at day 1 of both courses varied between 18 and 77 microM and at day 15 between 13 and 90 microM. The mean ratios day 8/day 1 and day 15/day 1 varied from 0.94 to 1.18. For the inactive metabolite 2',2'-difluoro-2'-deoxyuridine (dFdU) these values varied between 54 and 152 microM and 55 and 157, respectively, and the ratios from 0.96 to 1.08. The concentration of the active metabolite of gemcitabine, gemcitabine triphosphate (dFdCTP) in peripheral white blood cells, ranged between 37 and 283 pmol/10(6) cells at the end of infusion on day 1 and 35 and 115 pmol/10(6) cells on day 15. Potential accumulation was evaluated using a mixed effects model and no evidence was observed of accumulation for either gemcitabine or its metabolites. Gemcitabine can be administered safely without the risk that the drug will accumulate.

Aged↗
PubMed2005

[Three patients with autoimmune hepatitis: the importance of early diagnosis and remission].

A 70-year-old woman presented with impaired memory and depressive symptoms and two women aged 53 and 30 years, respectively, presented with general malaise and fatigue. All were diagnosed with and treated for autoimmune hepatitis (AIH). The first patient developed a relapse during treatment withdrawal; she recovered and maintained remission after the initial dose of medication had been restarted and the medication was tapered more gradually. The second patient had an incomplete remission and later developed liver failure; she was eligible for a liver transplant. The third woman became pregnant during treatment and developed a relapse after delivery; remission was induced and maintained after the immunosuppression was temporally increased. AIH is a chronic progressive liver disease characterised by abnormal serum levels of liver enzymes, hypergammaglobulinaemia, auto-antibodies against cell nuclei (ANA), smooth muscle (SMA), or liver and kidney microsomes (LKM), interface hepatitis and the absence of other chronic liver disease. Early diagnosis is essential because therapy can markedly improve prognosis. However, there is no specific diagnostic test for AIH. It is important to induce and maintain remission with immunosuppressive therapy.

Adult↗
PubMed2004

Quantitative real time PCR of deoxycytidine kinase mRNA by Light Cycler PCR; in relation to enzyme activity.

Deoxycytidine kinase (dCK) is essential for the phosphorylation of several deoxyribonucleosides and various analogues such as gemcitabine (2',2'-difluorodeoxycytidine). We developed and optimized a sensitive real time Light Cycler (LC) PCR assay for dCK with SYBR green detection. The enzymatic activity measured in the same human xenografts of dCK correlated excellently with dCK mRNA expression levels measured by the LC. This assay can be used for evaluation of dCK expression in tumors.

DNA Primers↗
PubMed2004

Phase II study of cisplatin preceding gemcitabine in patients with advanced oesophageal cancer.

BACKGROUND: For oesophageal cancer there is no effective standard therapy. We studied the feasibility and efficacy of the cisplatin-gemcitabine combination chemotherapy in patients with unresectable oesophageal cancer. PATIENTS AND METHODS: Thirty-six chemonaïve patients with unresectable or metastatic oesophageal adenocarcinoma (24) or squamous-cell-carcinoma (12) were treated with cisplatin (50 mg/m2, days 1 and 8), followed by gemcitabine (800 mg/m2, days 2, 9 and 16), every 28 days. Feasibility and efficacy were studied. RESULTS: Toxicity was substantial but manageable. A median number of four therapy cycles was given. The most frequent grade > or = 3 toxicities were leukopenia (75%) and neutropenia (83%). Three patients developed neutropenic fever. Grade 3/4 thrombocytopenia occurred in 24 out of 36 patients (67%), but did not result in serious bleeding disorders. Myelotoxicity was cumulative and required omission of gemcitabine on day 16 in 63% of cycles. Anaemia required treatment with erythropoietin, red blood cells or both in 81% of patients. Non-haematological toxicity consisted mainly of grade 1/2 nausea/vomiting or fatigue. Fourteen out of 34 evaluable patients had a major objective response (41%; two complete and 12 partial responses). The median actuarial survival was 9.8 months. CONCLUSION: This cisplatin-gemcitabine regimen was feasible, with myelosupression being the main toxicity, and had significant activity in patients with advanced oesophageal cancer.

Adenocarcinoma↗
PubMed2004

Phase II trial of cisplatin and gemcitabine in patients with advanced gastric cancer.

BACKGROUND: This phase II study was performed to determine the efficacy and toxicity of cisplatin and gemcitabine in patients with advanced gastric cancer. PATIENTS AND METHODS: Forty chemo-naïve patients with measurable locoregionally advanced or metastatic gastric cancer were included; the median patient age was 53 years (range 35-71). Cisplatin was administered at a dose of 50 mg/m2, given in 1 h intravenously (i.v.) on days 1 and 8, followed after 24 h by gemcitabine at a dose of 800 mg/m2 given in 30 min i.v. on days 2, 9 and 16, every 28 days. RESULTS: A median number of four therapy cycles were given (range 2-8). Myelosuppresion was the most important toxicity. Grade 3-4 thrombopenia was observed in 19 patients (48%) and grade 3-4 leukopenia was observed in 23 (58%). Myelotoxicity was cumulative and caused omission of gemcitabine on day 16 in 55% of cycles. Non-haematological toxicity consisted mainly of grade 1-2 nausea and vomiting. Objective responses were observed in 30% of patients including two complete remissions and 10 partial remissions. Median survival was 11 months (range 3-27+). CONCLUSIONS: This cisplatin-gemcitabine regimen had moderate efficacy in patients with advanced gastric cancer, with manageable toxicity. Further studies with this combination may be warranted.

Adenocarcinoma↗
PubMed2003

Expression of deoxycytidine kinase in leukaemic cells compared with solid tumour cell lines, liver metastases and normal liver.

Deoxycytidine kinase (dCK) is required for the phosphorylation of several deoxyribonucleoside analogues that are widely employed as chemotherapeutic agents. Examples include cytosine arabinoside (Ara-C) and 2-chlorodeoxyadenosine (CdA) in the treatment of acute myeloid leukaemia (AML) and gemcitabine to treat solid tumours. In this study, expression of dCK mRNA was measured by a competitive template reverse transcriptase polymerase chain reaction (CT RT-PCR) in seven cell lines of different histological origin, 16 childhood and adult AML samples, 10 human liver samples and 11 human liver metastases of colorectal cancer origin. The enzyme activity and protein expression levels of dCK in the cell lines were closely related to the mRNA expression levels (r=0.75, P=0.026 and r=0.86, P=0.007). In AML samples, dCK mRNA expression ranged from 1.16 to 35.25 (x10(-3)xdCK/beta-actin). In the cell line panel, the range was 2.97-56.9 (x10(-3)xdCK/beta-actin) of dCK mRNA expression. The enzyme activity in liver metastases was correlated to dCK mRNA expression (r=0.497, P=0.05). In the liver samples, these were not correlated. dCK mRNA expression showed only a 36-fold range in liver while a 150-fold range was observed in the liver metastases. In addition, dCK activity and mean mRNA levels were 2.5-fold higher in the metastases than in the liver samples. Since dCK is associated with the sensitivity to deoxynucleoside analogues and because of the good correlation between the different dCK measurements in malignant cells and tumours, the CT-RT PCR assay will be useful in the selection of patients that can be treated with deoxycytidine analogues.

Adult↗
PubMed2000

Differential effects of gemcitabine on ribonucleotide pools of twenty-one solid tumour and leukaemia cell lines.

To gain a more detailed insight into the metabolism of 2', 2'-difluoro-2'-deoxycytidine (dFdC, gemcitabine, Gemzar) and its effect on normal ribonucleotide (NTP) metabolism in relation to sensitivity, we studied the accumulation of dFdCTP and the changes in NTP pools after dFdC exposure in a panel of 21 solid tumour and leukaemia cell lines. Both sensitivity to dFdC and accumulation of dFdCTP were clearly cell line-dependent: in this panel of cell lines, the head and neck cancer (HNSCC) cell line 22B appeared to be the most sensitive, whereas the small cell lung cancer (SCLC) cell lines were the least sensitive to dFdC. The human leukaemia cell line CCRF-CEM accumulated the highest concentration of dFdCTP, whereas the non-SCLC cell lines accumulated the least. Not only the amount of dFdCTP accumulation was clearly related to the sensitivity for dFdC (R=-0.61), but also the intrinsic CTP/UTP ratio (R=0.97). NTP pools were affected considerably by dFdC treatment: in seven cell lines dFdC resulted in a 1.7-fold depletion of CTP pools, in two cell lines CTP pools were unaffected, but in 12 cell lines CTP pools increased about 2-fold. Furthermore, a 1.6-1.9-fold rise in ATP, UTP and GTP pools was shown in 20, 19 and 20 out of 21 cell lines, respectively. Only the UTP levels after treatment with dFdC were clearly related to the amount of dFdCTP accumulating in the cell (R=0.64 (P<0.01)), but not to the sensitivity to dFdC treatment. In conclusion, we demonstrate that besides the accumulation of dFdCTP, the CTP/UTP ratio was clearly related to the sensitivity to dFdC. Furthermore, the UTP levels and the CTP/UTP ratio after treatment were related to dFdCTP accumulation. Therefore, both the CTP and UTP pools appear to play an important role in the sensitivity to dFdC.

Animals↗
PubMed2000

Sequence dependent effect of paclitaxel on gemcitabine metabolism in relation to cell cycle and cytotoxicity in non-small-cell lung cancer cell lines.

Gemcitabine and paclitaxel are active agents in the treatment of non-small-cell lung cancer (NSCLC). To optimize treatment drug combinations, simultaneously and 4 and 24 h intervals, were studied using DNA flow cytometry and multiple drug effect analysis in the NSCLC cell lines H460, H322 and Lewis Lung. All combinations resulted in comparable cytotoxicity, varying from additivity to antagonism (combination index: 1.0-2.6). Gemcitabine caused a S (48%) and G1 (64%) arrest at IC-50 and 10 x IC-50 concentrations, respectively. Paclitaxel induced G2/M arrest (70%) which was maximal within 24 h at 10 x IC-50. Simultaneous treatment increased S-phase arrest, while at the 24 h interval after 72 h the first drug seemed to dominate the effect. Apoptosis was more pronounced when paclitaxel preceded gemcitabine (20% for both intervals) as compared to the reverse sequence (8%, P = 0.173 for the 4 h and 12%, P = 0.051 for the 24 h time interval). In H460 cells, paclitaxel increased 2-fold the accumulation of dFdCTP, the active metabolite of gemcitabine, in contrast to H322 cells. Paclitaxel did not affect deoxycytidine kinase levels, but ribonucleotide levels increased possibly explaining the increase in dFdCTP. Paclitaxel did not affect gemcitabine incorporation into DNA, but seemed to increase incorporation into RNA. Gemcitabine almost completely inhibited DNA synthesis in both cell lines (70-89%), while paclitaxel had a minor effect and did not increase that of gemcitabine. In conclusion, various gemcitabine-paclitaxel combinations did not show sequence dependent cytotoxic effects; all combinations were not more than additive. However, since paclitaxel increased dFdCTP accumulation, gemcitabine incorporation into RNA and the apoptotic index, the administration of paclitaxel prior to gemcitabine might be favourable as compared to reversed sequences.

Animals↗
PubMed1999

Pharmacokinetic schedule finding study of the combination of gemcitabine and cisplatin in patients with solid tumors.

PURPOSE: To determine possible schedule dependent pharmacokinetic and pharmacodynamic interactions between gemcitabine (2',2'-difluorodeoxycytidine, dFdC) and cisplatin (cis-diammine-dichloroplatinum, CDDP) in patients with advanced stage solid tumors in a phase I trial. PATIENTS AND METHODS: A total of 33 patients with advanced stage solid tumors were treated with gemcitabine (30-min infusion, 800 mg/m2) and cisplatin (one-hour infusion, 50 mg/m2). Sixteen patients had a four-hour interval between gemcitabine (days 1, 8, 15) and cisplatin (days 1 and 8), followed by the reverse schedule and seventeen patients had a 24-hour interval between gemcitabine (days 1, 8, 15) and cisplatin (days 2 and 9), followed by the reverse schedule. Gemcitabine and cisplatin pharmacokinetics were measured in plasma and white blood cells (WBC), isolated from blood samples taken at several time points after the start of treatment. RESULTS: A four-hour time interval between both agents did not reveal major differences in plasma pharmacokinetics of gemcitabine, dFdU (deaminated gemcitabine) and platinum (Pt), and of gemcitabine-triphosphate (dFdCTP) accumulation and Pt-DNA adduct formation in WBC between the two different sequences of gemcitabine and cisplatin. In the patients treated with the 24-hour interval, cisplatin before gemcitabine did not significantly change peak gemcitabine levels and the AUC of plasma dFdU, but tended to increase dFdCTP AUC in WBC 1.5-fold (P < 0.06). Gemcitabine before cisplatin decreased the plasma AUC of Pt 2.1-fold (P = 0.03). No significant differences in Pt-DNA adduct levels in WBC were found, although gemcitabine before cisplatin tended to increase the 24-hour retention of Pt-DNA adducts. Creatinine clearance on day 28 was related to the peak plasma levels of total Pt (linear regression coefficient (r) = 0.47, P = 0.02, n = 26). Furthermore, the increase in the Pt-GG to Pt-AG ratio 24 hours after cisplatin treatment was related to the overall response of patients (r = 0.89, P < 0.01, n = 8). CONCLUSIONS: Of all schedules the treatment of patients with cisplatin 24 hours before gemcitabine led to the highest dFdCTP accumulation in WBC and total Pt levels in plasma. These characteristics formed the basis for further investigation of this schedule in a phase II clinical study.

Adult↗
PubMed1999

Gemcitabine-cisplatin: a schedule finding study.

PURPOSE: To evaluate the tolerability of four alternating cisplatin-gemcitabine schedules. A secondary aim was to evaluate the clinical efficacy of this combination. PATIENTS AND METHODS: Forty-one patients with advanced solid tumors received alternating sequences with a 4- and 24-hour interval of cisplatin and gemcitabine. Gemcitabine 800 mg/m2 was administered as a 30-min infusion on day 1, 8 and 15, and cisplatin 50 mg/m2 over 1 hour on day 1 and 8; in case of the 24-hour time interval the second drug was administered one day later. Four cisplatin-gemcitabine schedules were studied: gemcitabine four hour before cisplatin (10 patients), or vice versa (14 patients) and gemcitabine twenty-four hours before cisplatin (9 patients) or vice versa (8 patients). The sequence of drug administration was reversed in the second cycle of therapy in each individual patient, enabling the evaluation of sequence-dependent side effects. Twenty-six patients had received prior chemotherapy, of which twenty-one platinum-based. RESULTS: The main toxicity was myelosuppression. Overall, grade 3 and 4 thrombocytopenia was observed in 27 out of 41 patients (66%) and was not schedule dependent. No serious bleeding occurred. Leukopenia was significantly different between the 4 alternating schedules (P = 0.01); gemcitabine 24 hours before cisplatin was significantly less toxic compared to both cisplatin 4 hours and 24 hours before gemcitabine (P = 0.01 and P = 0.003, respectively). Furthermore, paired analysis of the 4-hour and 24-hour data sets showed that leukopenia was significantly more serious when cisplatin preceded gemcitabine (P = 0.005). Although most patients received prior treatment, both prior chemotherapy and radiotherapy were not related to toxicity. Overall, grade 3 and 4 leukopenia occurred in 19 out of 41 patients (46%). Anemia (Hb < or = 6.0 mmol/l) was not sequence dependent and was observed in 63% of patients. Myelotoxicity was cumulative between cycles and caused frequent omission of gemcitabine on day 15. Overall, in 51% of administered cycles there was no omission of gemcitabine. A mean of 3.5 therapy cycles was administered. Non-hematological toxicity was moderate, consisting mainly of grade 1 and 2 nausea/vomiting and fatigue, and was not schedule dependent. Recently, we described that the schedule in which cisplatin was administered 24 hours before gemcitabine produced the best pharmacological profile. Based on this and because toxicity was manageable, the schedule cisplatin 24 hours prior to gemcitabine was chosen for phase II evaluation. Nine out of thirty-six evaluable patients had an objective response. These responses were observed in head and neck squamous-cell carcinoma (HNSCC), non-small-cell lung cancer (NSCLC), melanoma, adenocarcinoma of unknown origin, ovarian and esophageal carcinoma. CONCLUSIONS: Myelosuppression was the most important toxicity. Leukopenia was schedule dependent: gemcitabine before cisplatin was less toxic than the reversed sequence, in this respect. Some encouraging responses were seen in patients with esophageal cancer. Currently, a phase II study with cisplatin 24 hours before gemcitabine is ongoing in patients with advanced upper gastro-intestinal tumors.

Adult↗
PubMed1999

Gemcitabine and paclitaxel: pharmacokinetic and pharmacodynamic interactions in patients with non-small-cell lung cancer.

PURPOSE: To assess possible pharmacokinetic and pharmacodynamic interactions between gemcitabine and paclitaxel in a phase I/II study in non-small-cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: Eighteen patients with advanced NSCLC received the following in a 3-week schedule: gemcitabine 1,000 mg/m(2) (30 minutes, days 1 and 8) and paclitaxel 150 (n = 9) or 200 mg/m(2) (n = 9) before gemcitabine (3 hours, day 1). Plasma pharmacokinetics and pharmacodynamics in mononuclear cells were studied. RESULTS: Gemcitabine did not influence paclitaxel pharmacokinetics at 150 and 200 mg/m(2) (area under the concentration-time curve [AUC], 7.7 and 8.8 micromol/ L. h, respectively; maximum plasma concentration [C(max)], 3.2 and 4.0 micromol/L, respectively), and paclitaxel did not influence that of gemcitabine (C(max), 30 +/- 3 micromol/L) and 2',2'-difluorodeoxyuridine. Paclitaxel, however, dose-dependently increased the C(max) of gemcitabine triphosphate (dFdCTP), the active metabolite of gemcitabine, from 55 +/- 10 to 106 +/- 16 pmol/10(6) cells.( )No significant difference in the AUC of dFdCTP was observed. Moreover, the gemcitabine-paclitaxel combination significantly increased ribonucleotide levels, most pronounced for adenosine triphosphate (six- to seven-fold). Postinfusion paclitaxel AUC was related to pretreatment hepatic function (bilirubin: r = 0. 79; P <.001) and to the percentage decrease in platelets (r = 0.61; P =.009). The latter was also related to the duration of paclitaxel concentration above 0.1 micromol/L (r = 0.62; P =.007). Gemcitabine C(max )was related to the percentage decrease in platelets (r = 0. 58; P =.01), pretreatment hepatic function (bilirubin: r = 0.77; P <. 001), and to plasma creatinine (r = 0.5; P =.03). The pharmacokinetics and pharmacodynamics were not related to response or survival. CONCLUSION: Gemcitabine and paclitaxel pharmacokinetics were related to the percentage decrease in platelets. Paclitaxel did not affect the pharmacokinetics of gemcitabine, nor did gemcitabine affect the pharmacokinetics of paclitaxel, but paclitaxel increased dFdCTP accumulation. This might enhance the antitumor activity of gemcitabine.

Aged↗
PubMed1999

Experimental drugs and drug combinations in pancreatic cancer.

The current role of chemotherapy in pancreatic cancer is limited. Chemotherapy usually consists of 5-fluorouracil (5FU) and gemcitabine either as a single agent or in combinations. However, response rates are below 15% with minor effects on overall survival. Due to the aggressive behavior of the disease, current emphasis of new experimental chemotherapy is also focusing on clinical benefit: improvement of pain, performance status or weight. The results with gemcitabine indicated that evaluation of new chemotherapeutic agents in pancreatic cancer should not be limited to the evaluation of response rates; single agent gemcitabine not only showed higher response rates than 5FU, but also resulted in clinical benefit for the patients. Several new agents have been introduced into the clinic for treatment of various gastro-intestinal malignancies, whereas novel agents with different types of targets, such as marimastat deserve further attention. Several oral formulations of 5FU, such as capecitabine, UFT, and eniluracil with 5FU, aim to simulate long-term continuous infusion. Response rates of these formulations are comparable to those of 5FU continuous infusion and 5FU bolus injections. However, the convenience of oral administration with reliable plasma drug concentrations makes these agents very attractive as a replacement of traditional 5FU administration. Since 5FU acts by inhibition of thymidylate synthase (TS), resulting in inhibition of DNA synthesis, several new antifolates, directed towards TS, have been developed. However, these agents, such as ZD1694 (Tomudex, Raltitrexed) and LY231514 (MTA, multitargetted antifolate) showed only limited efficacy. Other new agents active in colorectal cancer, e.g. the topoisomerase I inhibitors topotecan and CPT-11, showed only minor activity. The same was observed for the taxanes. Combinations of gemcitabine (cisplatin, 5FU, epirubicin, marimastat) show promising activities, not only regarding response but also with respect to clinical benefit. The effects were better than that for each agent separately. Thus, despite limited activity of single agents, novel combinations especially with gemcitabine are promising, with emphasis on improvement of the clinical benefit of patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

The iontophoresis of fentanyl citrate in humans.

BACKGROUND: Iontophoresis is a method of transdermal administration of ionizable drugs in which the electrically charged components are propelled through the skin by an external electric field. This study was designed to determine whether iontophoresis could be used to deliver clinically significant doses of fentanyl in humans and whether there is a charge-dose relation in the delivery of fentanyl by iontophoresis. METHODS: Five adult volunteers were tested three times on separate days, once receiving passive treatment of 0.0 mA for 2 h (0 mA.min), iontophoresis 1.0 mA for 2 h (120 mA.min), and iontophoresis 2.0 mA for 2 h (240 mA.min) in an open, randomized, crossover design. Respiratory rate, heart rate, blood pressure, and hemoglobin oxygen saturation were monitored throughout the study. Plasma fentanyl concentrations were measured several times before, during, and after iontophoresis. Plasma fentanyl concentrations were measured by radioimmunoassay. RESULTS: No fentanyl was detected after passive (0.0-mA) fentanyl delivery. The following results were obtained for the 1.0- and 2.0-mA deliveries, respectively. Mean times to detectable concentrations of plasma fentanyl were 33 and 19 min; mean times to maximum concentration were 122 and 119 min; maximum concentrations were 0.76 and 1.59 ng/ml (P = 0.010); mean areas under the curve of the plasma fentanyl concentration versus time relation were 233 and 474 ng.ml-1.min (P = 0.003); and mean elimination half-lives were 354 and 413 min (P = 0.326). Only minor adverse side effects related to iontophoresis occurred. However, typical opioid-related effects occurred frequently in the 1.0- and 2.0-mA administration groups. CONCLUSIONS: Clinically significant doses of fentanyl can be administered by iontophoresis for delivery periods of 2 h. A charge-dose relation exists after administration with currents of 1.0 and 2.0 mA. Future research into the iontophoresis of fentanyl as a method of potent opioid administration is indicated.

Adult↗