Absorption and disposition including enterohepatic circulation of (14C) roquinimex after oral administration to healthy volunteers.

The absorption and disposition of roquinimex (Linomide) were studied in four male and two female healthy volunteers. The subjects received a single oral aqueous solution of 14C-labelled roquinimex, about 0.1 mg/kg, after an overnight fast. Blood samples were taken and urine and faeces were collected for 10 days after dosing. The plasma, urine and faeces concentrations of roquinimex and metabolites were determined by high-performance liquid chromatography (HPLC) with radiochemical detection. The metabolites were identified by HPLC-mass spectroscopy (MS). The plasma concentration-time profiles of roquinimex exhibited a rapid absorption followed by a bi-exponential disposition. A secondary peak was observed between 6 and 8 h, indicating enterohepatic circulation (EHC) of roquinimex. The terminal disposition half-life was estimated as 27 h. The primary metabolic pathways of roquinimex were hydroxylation, demethylation and conjugation. The major compound in plasma was roquinimex; metabolites were only occasionally detected. In urine and faeces, roquinimex accounted for 2% of the dose and conjugated and hydroxylated metabolites each accounted for about 30% of the dose. A model was derived for the plasma concentrations of roquinimex and the amount of urinary excreted roquinimex to take into account EHC. This model improved the goodness-of-fit according to common goodness-of-fit criteria. The values of the pharmacokinetic parameters were similar using compartmental and non-compartmental methods, indicating that the contribution of EHC of roquinimex is of minor importance in the evaluation of the pharmacokinetics of roquinimex.

Metabolism of roquinimex in mouse and rat: an in vitro/in vivo comparison.

1. In vitro studies with roquinimex, an immuno-modulator, in liver microsomes from mouse and rat were conducted to evaluate the primary metabolism and compare the metabolite pattern as well as the rate of metabolism with the in vivo pharmacokinetics of the compound in these two species. 2. In the presence of NADPH, roquinimex was metabolized to six primary metabolites (R1-6) by liver microsomes from mouse and rat. The formation of these metabolites was qualitatively similar in both species, and was greatly enhanced by pretreatment with PCN, an inducer of cytochrome P4503A. 3. The identification of the R1-6 demonstrated that roquinimex had been hydroxylated and demethylated. Hydroxylation at different sites of the quinoline moiety was the dominating reaction in both species. 4. Comparison of the resulting microsomal intrinsic clearance of 0.3 micromol mg(-1) protein min(-1) in mouse liver microsomes, versus 0.03 micromol mg(-1) protein min(-1) in rat liver microsomes demonstrated that the mouse possesses about a 10-fold greater metabolic capacity for roquinimex than the rat. 5. The in vivo pharmacokinetics of roquinimex demonstrated a 7-fold higher clearance in mouse than in the rat (82 ml h(-1) kg(-1) in mouse, 10.6 ml h(-1) kg(-1) in rat), which is in concordance with the in vitro findings.

Dissolution rate-limited absorption and complete bioavailability of roquinimex in man.

In order to investigate the bioavailability and the rate-limiting step of the absorption of roquinimex, an oral solution and a tablet formulation (Linomide(R)) were given to healthy volunteers. The study was conducted as a randomized three-period crossover study in seven male and seven female healthy volunteers. The subjects received an intravenous infusion, an oral solution and an oral tablet formulation, each of 5 mg (about 0.07 mg kg(-1)), as single doses after an overnight fast on three occasions, with a wash-out period of 3 weeks in between. Venous blood samples were taken over 7 days and the plasma concentrations of roquinimex were determined by high-performance liquid chromatography (HPLC) with ultraviolet (UV)-detection. The pharmacokinetics of roquinimex was characterized by a low plasma clearance, 4.9 mL h(-1) kg(-1) and a small volume of distribution, 0.22 L kg(-1). The oral bioavailability of the drug was complete for both the solution and the tablet formulation. The absorption rate was faster for the solution than for the tablet. The disposition of roquinimex was biphasic, with a terminal disposition half-life of 32 h. Between 4 and 8 hours after dosing, a secondary plasma peak was observed, indicating enterohepatic circulation of the drug. No major sex differences were shown in the pharmacokinetics of roquinimex. In conclusion, dissolution rate-limited absorption of roquinimex was shown, which demonstrates that disintegration and dissolution of the tablet play a major role in the absorption process of roquinimex. Despite the delayed absorption after administration of the tablet, the extent of absorption was complete.

Anti-angiogenic treatment with linomide as adjuvant to surgical castration in experimental prostate cancer.

PURPOSE: Escape from "castration inhibition," be it surgical or chemically induced, is still the major problem in prostate cancer treatment. New agents that can be given as adjuvant therapy are needed. Linomide has demonstrated both anti-tumor and anti-angiogenic activity with little toxicity in the Dunning R-3327 rat prostate tumor system. Therefore it was deemed essential to study the efficacy of this drug in the adjuvant situation. MATERIALS AND METHODS: Linomide, roquinimex, was administered 3 times a week i.p. alone or in conjunction with castration to rats bearing the Dunning R-3327 PAP rat prostate tumor and its effect on tumor growth analyzed. Similar experiments, in which Linomide 25 mg./kg./day was given in the drinking water were carried out in rats with the Dunning R-3327 G tumor. The effect of treatment on blood vessel density and blood flow in the tumor was also assessed using an image analysis system. RESULTS: Linomide, 2.5 & 40 mg./kg., administered from the day after castration inhibited the regrowth of the Dunning R-3327 PAP tumors In addition, Linomide 40 mg./kg. administered after tumor regrowth occurred following castration(week 10) inhibited further tumor growth. Inhibition of tumor regrowth after castration was also found in the Dunning G tumor. When Linomide treatment was stopped regrowth of the tumors occurred, either in the same animal or on transplantation to new intact hosts, demonstrating that the tumor cells were still viable. Tumor blood vessel density was decreased both after castration and Linomide treatment alone, 40 and 32% respectively. On combination of castration and Linomide a 60% decrease in blood vessel density was found. This was significantly different from either of the two treatments given alone. The enhancement on combining castration and Linomide was confirmed by a further decrease in blood flow, from 19 and 22 to 12 ml. per minute/gm. tissue respectively. CONCLUSIONS: Linomide, an anti-angiogenic drug, inhibits escape from "castration inhibition".

The first clinical pilot study of roquinimex (Linomide) in cancer patients with special focus on immunological effects.

Roquinimex (Linomide) has been demonstrated to suppress tumor growth in animal models. The effect is at least in part related to enhanced numbers and activity of natural killer (NK) cells. In this clinical pilot study, roquinimex was given at increasing doses (0.05 mg/kg to 0.6 mg/kg) to 13 patients (performance status 0-3) with various malignant disorders. Immunology parameters were followed and side effects were observed during the study. The plasma pharmacokinetics of roquinimex was studied at the 0.2 mg/kg dose level. The clinical side effects were dominated by musculoskeletal discomfort, nausea, and pain. No significant hematological or biochemical toxicity was observed. Pharmacokinetic analysis at the 0.2 mg/kg dose level revealed a Cmax of 4.0 mumol/L at tmax of 1.2 hr and an elimination half-life of 42 hr. Increased numbers of phenotypic NK cells, activated T (DR+CD4+) cells, and monocytes were observed after administration of roquinimex compared with pretreatment values. Roquinimex seems to be an active immunomodulator with manageable toxicity. Further exploration of therapeutic efficacy is warranted.

Metabolism of lofepramine and imipramine in liver microsomes from rat and man.

1. The in vitro metabolism of lofepramine was studied in comparison with imipramine. Both compounds were hydroxylated and demethylated by a NADPH-generating system in rat and human liver microsomes. 2. Three metabolites were in common for the two drugs, namely desipramine (DMI), 2-hydroxydesipramine (2-OH-DMI) and didesmethylimipramine (DDMI). 3. Lofepramine was also metabolized to three unique tricyclic metabolites. Comparisons with authentic reference compounds suggested that two of these metabolites were 2-hydroxylofepramine and desmethyllofepramine. 4. The ratio between the concentrations of DDMI and DMI was higher for lofepramine than imipramine. This is probably due to DDMI formation via two parallel metabolic pathways of lofepramine, i.e. DMI and desmethyllofepramine, respectively. 5. It is speculated that the different metabolic pattern of lofepramine as compared with desipramine and imipramine is of importance for the therapeutic profile of the drug.

The quinoline-3-carboxamide linomide inhibits angiogenesis in vivo.

Linomide (Roquinimex) has antitumor activity when given in vivo (but not when applied in vitro) that has been attributed to immune host mechanisms. Recent studies, however, suggest that Linomide may also possess antiangiogenic properties. The aim of the present study was to evaluate the antiangiogenic effect of Linomide using an intravital microscopic technique. Syngeneic pancreatic islets were isolated and implanted into the dorsal skinfold chamber of Syrian golden hamsters. This model allows detailed repeated in vivo observations and quantitative analysis of revascularization of pancreatic islet grafts. The neovascularization process of the islets is a highly reproducible phenomenon that is completed within about 2 weeks, resulting in a microvascular network very similar to that of islets in situ. The plasma concentration profile of Linomide following a single oral dose of the compound was determined. The elimination of Linomide was fast, the half-life being 2.6 +/- 0.2 h. Due to the short half-life, the hamsters were given Linomide twice a day. One group of animals (n = 9) was force-fed Linomide (100 mg/kg per day) from the day of implantation throughout the 2-week observation period, and the results were compared with those obtained in a nontreated control group (n = 7). At days 6, 10, and 14 after implantation, the neo-vasculature of the islets was examined. In the control group, 91% +/- 4% (mean +/- SEM) of the islets showed the first signs of angiogenesis at day 6, whereas in the Linomide-treated group the corresponding value was 48% +/- 12%. At days 10 and 14, the "take-rate" in the control group increased to 94% +/- 3% for day 0 and to 94% +/- 4% (n = 6) for day 14, whereas in the treated group the corresponding take-rate was 67% +/- 11% and 72% +/- 12%, respectively. The functional capillary density in the control group at days 6, 10, and 14 was 223 +/- 17,348 +/- 29, and 495 +/- 29 cm-1, respectively, and that in the Linomide treated group was 91 +/- 28, 181 +/- 43, and 229 +/- 47 cm-1, respectively. These results demonstrate that Linomide suppresses the neovascularization of the islet grafts by both delaying the onset of and reducing the percentage of islets displaying angiogenesis as well as by decreasing the rate of proliferation of capillary endothelium of the revascularized islets.