Development and validation of an RP-HPLC-UV method for the determination of BOL-303225-A, a new coumarin-based anti-inflammatory drug, in rat plasma

A simple and rapid high-performance liquid chromatographic method was developed and validated for the analysis in rat plasma of BOL-303225-A, a new coumarin-based anti-inflammatory drug. Liquid-liquid extraction was used for sample preparation. Chromatographic separation was achieved on a C(18) column using acetonitrile and water containing 1% triethylamine pH 3.5, adjusted with orthophosphoric acid (35.5:64.5 v/v) as mobile phase. The UV detector was set at 324 nm. The method proved to be linear (r(2) > 0.99) and precise (RSD < 7%) over the concentration range 29-940 ng/mL, and was suitable for the support of pharmacokinetic studies in rats.

Novel polysaccharides-based viscoelastic formulations for ophthalmic surgery: Rheological characterization

Different formulations based on bioadhesive and biocompatible polymers, hydroxypropylmethylcellulose (HPMC), sodium hyaluronate (SH) and chitosan glutamate (CG), were prepared to be potentially used as ophthalmic viscosurgical device (OVD) during cataract surgery. Their rheological properties were analyzed in terms of flow and oscillation properties and compared to a commercially available OVD, widely employed in cataract surgery, named Viscoat. All the formulations tested presented a pseudoplastic behavior during flow. Primary systems containing HPMC or CG and HPMC/CG binary systems behaved as viscous solution (G''>G') over the range of oscillatory frequencies observed, while the primary systems containing SH and HPMC/SH binary formulations and showed an entangled network behavior when subjected to a sinusoidal stress. By increasing the SH concentration in the binary systems, the viscoelastic parameters, G'and G'', and zero frequency viscosity (derived from the Cross model) increased. Viscoat presents viscoelastic parameters values lower than the corresponding values of all the binary formulations of HPMC/SH and higher than all the formulations made up of CG and HPMC. As regard to HPMC/SH binary system, the cross-over frequency decreased by increasing SH concentration in the systems and it was the highest for Viscoat and thus the opposite occurred for the relaxation time. The rheological synergy in the binary formulations was assessed by calculating the interaction parameters which increased as a function of SH and CG concentration in the binary systems. The values of the interaction parameters of the formulations based on CG, are lower than 10 Pa indicating that they did not interact synergically while the formulations based on SH show high values of the interactions parameters (in the range from 55 to 130 Pa). This indicates that secondary bonds formation occurs between SH and HPMC. From the rheological analysis it can be concluded that the binary formulations based on CG do not possess appropriate features to be used as OVD while both the viscoelastic and the flow properties of the binary formulations made up of SH and HPMC are suitable for their application as OVD being able to maintain the ocular spaces and to be easily administrated. Moreover, thank to the adhesive properties of both components, the binary formulation should be able to interact with corneal endothelium so offering a durable protection to ocular tissue. On the basis of the rheological characterization presented in this work, we concluded that the binary system named VISC26 (HPMC at 0.8% and SH at 2.3%) represents the formulation that better fulfill the OVD requirements.

Preparation and characterization of eudragit retard nanosuspensions for the ocular delivery of cloricromene

The purpose of this study was to improve the stability of cloricromene (AD6) in ophthalmic formulations and its drug availability at the ocular level. To this end, AD6-loaded polymeric nanoparticle suspensions were made using inert polymer resins (Eudragit RS100 and RL100). We modified the quasi-emulsion solvent diffusion technique by varying some formulation parameters (the drug-to-polymer ratio, the total drug and polymer amount, and the stirring speed). The chemical stability of AD6 in the nanosuspensions was assessed by preparing some formulations using (unbuffered) isotonic saline or a pH 7 phosphate buffer solution as the dispersing medium. The formulations were stored at 4 degrees C, and the rate of degradation of AD6 was followed by high performance liquid chromatography (HPLC). The obtained nanosuspensions showed mean sizes and a positive surface charge (zeta-potential) that make them suitable for an ophthalmic application; these properties were maintained upon storage at 4 degrees C for several months. In vitro dissolution tests confirmed a modified release of the drug from the polymer matrixes. Nanosuspensions prepared with saline solution and no or lower amounts of surfactant (Tween 80) showed an enhanced stability of the ester drug for several months, with respect to an AD6 aqueous solution. Based on the technological results, AD6-loaded Eudragit Retard nanoparticle suspensions appear to offer promise as a means to improving the shelf life and bioavailability of this drug after ophthalmic application.

A novel adamantane derivative attenuates retinal ischemia-reperfusion damage in the rat retina through sigma1 receptors

The effects of a novel N-methyladamantan-1-amine derivative [(-)-MR22] with high sigma1 receptor affinity were investigated on retinal degeneration using a rat model of ischemia-reperfusion injury. The animals were anaesthetized and retinal ischemia was induced by elevating the intraocular pressure to 120 mm Hg for 45 min. The drug was injected intraperitoneally before the ischemic damage. Retinal biochemical changes, i.e. increase of lactate content and decrease of glucose and ATP were significantly inhibited by the new and selective sigma1 receptor ligand compared to the ischemic control group. The effect of (-)-MR22 was antagonized by pre-treatment with the sigma1 site antagonist. The protective effect of (-)-MR22 on ischemic retina was confirmed by the histological analysis. These findings suggest that (-)-MR22 serves as a retinal neuroprotective agent and acts as a sigma1 receptor agonist.

Possible involvement of nitric oxide in morphine-induced miosis and reduction of intraocular pressure in rabbits

The role of mu3 opioid receptors in morphine-induced intraocular pressure (IOP) lowering effect and miosis was evaluated in conscious, dark-adapted New Zealand white (NZW) rabbits using a masked-design study. IOP and pupil diameter (PD) measurements were taken at just before and 0.5, 1, 2, 4, 6 h after monolateral instillation of morphine (10, 50 and 100 microg/30 microl) as compared to vehicle administered in the contralateral eye. Morphine-induced ocular effects were challenged by a pre-treatment with the non-selective opioid receptor antagonist, naloxone (100 microg/30 microl), the nitric oxide synthase inhibitor, N(omega)-nitro-L-arginine methyl ester (L-NAME, 1%, 30 microl), or the non-selective mu3 opioid receptor inhibitor, reduced L-glutathione (GSH, 1%, 30 microl). Morphine induced a dose-dependent decrease in IOP and PD. Pre-treatment with naloxone totally prevented morphine-induced decrease in IOP and miosis. Ocular administration of L-NAME or GSH alone failed to affect IOP or PD of NZW rabbits. However, pre-treatment with either drugs significantly reduced, but not totally prevented ocular effects of morphine. These results suggest that biochemical mechanisms related to nitric oxide release are involved, at least in part, in morphine effects on the eye. Since the mu3 opioid receptor subtype is able to release nitric oxide and is sensitive to inactivation by GSH, it may be possible that mu3 opioid receptors are involved in morphine-induced miosis and reduction in IOP.

Sigma receptor ligands protect human retinal cells against oxidative stress

This study was undertaken to investigate the role of sigma receptors during the oxidative damage on human retinal pigment epithelial cells, and to assess whether sigma receptor ligands enhance survival and protect DNA of cells challenged by oxidative stress. Pretreatment with PRE-084, a sigma1 receptor agonist, resulted in significant increased viability in a dose-related manner. DNA damage induced by oxidative insult was significantly lower with PRE-084. The effects of PRE-084 were antagonized by pretreatment with sigma1 receptor antagonists (NE-100 and BD1047), but interestingly were synergized by cotreatment with BD1047 that also presented an affinity for the sigma2 receptor. The results suggest that sigma1 receptors play an important role against retinal damage, even though sigma2 receptor involvement cannot be excluded.

Systemic omega-6 essential fatty acid treatment and pge1 tear content in Sjögren's syndrome patients

PURPOSE

To determine the effect of oral omega-6 essential fatty acids on PGE(1) tear content and signs and symptoms of ocular discomfort in patients with Sjögren's syndrome (SS).

METHODS

This randomized, double-masked, controlled, clinical trial involved 40 patients with primary SS, divided into two groups: group 1: 20 patients (18 women, 2 men; mean age, 36.9 +/- 7.9 years [SD]) treated for 1 month with linoleic acid (LA; 112 mg), and gamma-linolenic acid (GLA; 15 mg) administered twice daily; group 2: 20 patients (19 women, 1 man; mean age, 36.3 +/- 5.5 years) treated twice daily with placebo. Patients underwent three examinations: at baseline (T0), after 1 month of treatment (T1), and 15 days after suspension of treatment (T2). At each examination, the following tests were performed: tear sampling (2 microL) from the inferior meniscus, tear break-up time (BUT), fluorescein stain of the ocular surface, and tear basal secretion. A symptom score was also obtained at each examination. PGE1 was evaluated by enzyme immunoassay. The primary efficacy variable was PGE1 content of tears.

RESULTS

The tear PGE1 levels were significantly increased in group 1 at T1 versus T0 (PGE1 level: T0, 44 +/- 5.4 ng/mL; T1, 58.3 +/- 5.5 ng/mL; P < 0.01 versus T0 and group 2 at T1). At examination T2, a statistically significant reduction of PGE1 levels toward baseline was observed (45.7 +/- 5.2 ng/mL; P < 0.01 versus T1). A statistically significant reduction of symptom score was observed in group 1 at examination T1 (P < 0.01 versus T0 and group 2 score). At examination T2, the symptom score was significantly higher than T1 but remained lower than T0. The corneal fluorescein stain in group 1 showed a statistically significant improvement at examination T1 versus T0 and group 2 (P < 0.01). This improvement was also present at T2 (P < 0.02). No statistically significant differences were found for the other tests. No statistically significant changes were observed in the patients in group 2 at all examination time points.

CONCLUSIONS

Omega-6 administration increases the PGE1 levels in tears of patients with SS and improves ocular surface signs and symptoms of ocular discomfort.

Neuroactive steroids protect retinal pigment epithelium against oxidative stress

This study was undertaken to assess whether neuroactive steroids, 17beta-estradiol and dehydroepiandrosterone-sulfate, enhance survival and protect DNA of human retinal pigment epithelial cells challenged by oxidative stress, and to investigate the role of sigma1 receptors in the effects of neuroactive steroids. Retinal pigment epithelial cells were treated with various concentrations of neuroactive steroids and then exposed to hydrogen peroxide. Pretreatment with steroids resulted in significant increased viability in a dose-related manner. DNA damage induced by oxidative insult was significantly lower with steroid pretreatment. The effects of 17beta-estradiol and dehydroepiandrosterone-sulfate were antagonized by pretreatment with a sigma1 receptor antagonist. The results suggest that neuroactive steroids protect retinal cells from oxidative stress, and that this effect is mediated by sigma1 receptors.

Simple determination of riluzole in rat brain by high-performance liquid chromatography and spectrophotometric detection

A simple method was developed for separation and quantification of riluzole in rat brain. The analyses were performed by high-performance liquid chromatography using a C18 reversed-phase column (Hypersil ODS) with UV detection at 264 nm. The mobile phase consisted of methanol-water containing 1% triethylamine adjusted with orthophosphoric acid to pH 3.2. The retention time was 8.6 min. A simple liquid-liquid extraction with ethyl acetate was used to obtain riluzole from brain samples. The limit of quantification was 10 ng/g. The recovery was about 80%. The relationship between peak areas and concentrations was linear over the range between 0.01 and 0.8 microg/g, with r2 value over 0.99. The assay provided good reproducibility and accuracy and proved to be suitable for pharmacokinetic studies of riluzole.

Effects of neurosteroids on ischemia-reperfusion injury in the rat retina: role of sigma1 recognition sites

The effects of neurosteroids, 17beta-estradiol and dehydroepiandrosterone-sulfate (DHEA-S), were investigated on retinal degeneration using a rat model of ischemia-reperfusion injury. The animals were anaesthetized and retinal ischemia was induced by elevating the intraocular pressure to 120 mm Hg for 45 min. Neurosteroids were injected intraperitoneally before ischemia and immediately after reperfusion. Retinal biochemical changes such as increase of lactate content and decrease of glucose and ATP were significantly inhibited by neurosteroids compared to the control ischemic group. The effects of 17beta-estradiol and DHEA-S were antagonized by pre-treatment with the sigma1 site antagonist. These findings suggest that 17beta-estradiol and dehydroepiandrosterone-sulfate may affect the metabolic state of surviving neurons and glial cells after ischemic injury and that they act, at least in part, through involvement of sigma1 recognition sites.

Topical application of a nitric oxide synthase inhibitor reduces intraocular pressure in rabbits with experimental glaucoma

The role of nitric oxide (NO) in neuronal degeneration of glaucoma is well established, and drugs to inhibit NO production have been introduced in preclinical studies. The present experiments were made to investigate the pharmacological efficacy of a topical formulation of the nonselective nitric oxide synthase (NOS) inhibitor, nitro-L-arginine methyl ester (L-NAME), in an experimental model of glaucoma in rabbits. L-NAME was dissolved in an isotonic, mucoadhesive, viscosized, buffered solution in concentrations of 0.1%, 0.5%, or 1% (w/v). Ocular hypertension (of at least 15 mmHg compared to basal values) was induced by intra-ocular injection of alpha-chymotrypsin. The instillation of L-NAME topical formulations lowered the IOP of hypertensive rabbits in a dose-related manner, with a maximum drop of 12.0 mmHg 60 minutes after administration of the highest concentration. The area under the curve (AUC) of the DeltaIOP (mmHg) versus time (minutes) was 1050.3 +/- 141.7 and 15.1 +/- 2.5 for the 1% L-NAME-treated group and vehicle-treated group, respectively. No change was found in IOP or pupil diameter after instillation of L-NAME eye drops in normotensive rabbits. This study provides the first evidence that topical L-NAME significantly reduces the IOP in a model of ocular hypertension.

Hyaluronan-Induced Stimulation of Corneal Wound Healing is a Pure Pharmacological Effect

The aim of this study was to evaluate whether corneal reparative activity of hyaluronan is a concentration-dependent phenomenon. Corneal blocks from rabbit eyes were cultured for 20 hours with hyaluronan in different concentrations and molecular weight ranges. In another experiment, the corneal epithelium was denuded and hyaluronan was administered as eye drops. Distances of epithelial migration increased over exposed stroma proportionally to concentration, when hyaluronan was added with a molecular weight of 800-1,400 kD. Maximum effect was observed with 0.2% hyaluronan concentration. No difference was seen when corneal blocks were cultured with hyaluronan 0.2% in different molecular weight ranges (800-1,400, 1,400-2,000, and 2,000-2,600 kD). When hyaluronan (molecular weight, 800-1,400 kD) eye drops were administered after corneal epithelial denudation in rabbits, it was found to have faster wound reparation. This effect was concentration-dependent. The 2 highest concentrations (0.2% and 0.4%) were not different for the time needed to complete wound healing. In conclusion, hyaluronan-induced stimulation of corneal wound healing fulfills standards for being considered as a pharmacological effect.

Rapid determination of nimesulide in rabbit aqueous humor by liquid chromatography

A rapid method was developed for quantification of nimesulide (methanesulfonamide, N-[4-nitro-2-phenoxyphenil]) in rabbit aqueous humor. The analyses were performed by high-performance liquid chromatography using a C(18) reversed-phase column (Ultracarb ODS) with UV detection at 300 nm. The mobile phase consisted of acetonitrile-water containing 1% triethylamine (TEA) adjusted to pH 3.2 with orthophosphoric acid. The retention time was 4.5 min. A simple pre-treatment with acetonitrile was used to deproteinize aqueous humor samples. The limit of quantitation was 50 ng/ml. The recovery was over 90%. The relationship between peak areas and concentration was linear over the range between 0.05 and 2.5 microg/ml, with r(2) values over 0.99. The assay provided good reproducibility and accuracy and proved to be suitable for pharmacokinetic studies of nimesulide.

Effects of Hyaluronan on Free-Radical Formation, Corneal Endothelium Damage, and Inflammation Parameters After Phacoemulsification in Rabbits

Free-radical formation may play a role in postoperative complications of phacoemulsification (e.g., corneal endothelium damage from mechanical injury). The present experiments were aimed at investigating whether different molecular weight ranges (2000-2600, 2600-3200, or 3200-3800 kDa) of hyaluronan may influence free radical formation, corneal endothelium damage, and inflammation parameters after phacoemulsification in the rabbit eye. The viscoelastic substance was injected in the anterior chamber of rabbits' eyes before phacoemulsification, at a 2.5% concentration. The formation of free radicals was determined by adding luminol to the irrigation media and measuring the chemoluminescence in eyes. The corneal endothelial damage was evaluated by measuring the corneal central thickness by pachimetry. The inflammation parameters were measured by calculation in aqueous humor of peak levels of leukocytes and prostaglandin E(2) (PGE(2)) and evaluation in uveal tissue of myeloperoxidase activity. Hyaluronan decreased by about 58-60% free-radical formation during phacoemulsification, reduced by about 76-80% modifications in mean corneal thickness and by about 54-61% the corneal endothelial cell loss in all molecular weight ranges used. No difference was found among various molecular weight ranges. The highest molecular weight range showed to be more potent than the lowest range for reduced number of inflammation cells and level of PGE(2) in aqueous humor. Thus, hyaluronan reduces free-radical formation, exerts protection on the corneal endothelium and exerts anti-inflammation properties after phacoemulsification in rabbits. The latter effect seems to depend on the molecular weight of the substance.

Enhancer effects on in vitro corneal permeation of timolol and acyclovir

The aim of this study was to evaluate the ability of two non-toxic skin penetration enhancers, N-methylpyrrolidone (NMP) and a positively charged phospholipid mixture (PS), to increase in vitro corneal permeation of timolol maleate (TM) and acyclovir (AC) in comparison with two corneal absorption promoters, polyethylene glycol octadecyl ether (Brij 78) and sodium taurocholate (TA). In vitro experiments were performed on corneas from albino rabbits which were mounted in a perfusion apparatus. The concentrations of the enhancers being tested were: Brij 78 1%, PS 1%, TA 1%, NMP 5%, NMP 10%. The safety of the enhancers being tested was assessed in vitro by determining their effects on corneal hydration and in vivo by means of a modified Draize test. Calculating the amount of drug permeated at different time points (90 and 180 min) we observed that TA, PS and NMP 5% significantly increased the cumulative amount of AC permeated after 90 min but only PS was effective after 180 min. TA, Brij 78 and PS were able to increase significantly the amount of TM permeated after 90 min but after 180 min only Brij 78 retained its effect. TA, Brij 78 and NMP 10% significantly increased the percent hydration levels (% HL) compared to the control while PS and NMP 5% did not affect % HL. The results of in vivo ocular tolerability studies showed that the enhancers which caused an in vitro increase of % HL produced in vivo conjunctival and/or corneal damages. The results of this study suggest that PS could be regarded as a potential corneal enhancer to increase the intraocular bioavailability of AC and TM.

Influence of preparation conditions on acyclovir-loaded poly-d,l-lactic acid nanospheres and effect of PEG coating on ocular drug bioavailability

PURPOSE

The evaluation of nanosphere colloidal suspensions containing acyclovir as potential ophthalmic drug delivery systems was carried out. The influence of polymer molecular weight and type and concentration of various surfactants on nanosphere properties was studied. The ocular pharmacokinetics of acyclovir-loaded nanoparticles was evaluated in vivo and compared with an aqueous suspension of the free drug.

METHODS

Nanospheres were made up of poly-d,l-lactic acid (PLA). The colloidal suspension was obtained by a nanoprecipitation process. The surface properties of PLA nanospheres were changed by the incorporation of pegylated 1,2-distearoyl-3-phosphatidylethanolamine. The mean size and zeta potential of the nanospheres were determined by light scattering analysis. The acyclovir loading capacity and release were also determined. In vivo experiments were carried out on male New Zealand rabbits. The ocular tolerability of PLA nanospheres was evaluated by a modified Draize test. The aqueous humor acyclovir levels were monitored for 6 h to determine the drug's ocular bioavailability for the various formulations.

RESULTS

A reduction of the mean size and a decrease of the absolute zeta potential of PLA nanospheres resulted from increasing the surfactant concentration. The higher the polymer molecular weight, the smaller the nanosphere mean size. PEG-coated and uncoated PLA nanospheres showed a sustained acyclovir release and were highly tolerated by the eye. Both types of PLA nanospheres were able to increase the aqueous levels of acyclovir and to improve the pharmacokinetics profile, but the efficacy of the PEG-coated nanospheres was significantly higher than that of the simple PLA ones.

CONCLUSIONS

PEG-coated PLA nanospheres can be proposed as a potential ophthalmic delivery system for the treatment of ocular viral infections.

Pharmacokinetic profile of topical flunarizine in rabbit eye and plasma

The purpose of this study was to determine the aqueous humor, cornea, iris-ciliary body, retina and plasma levels and pharmacokinetics of a new topical formulation containing 0.05% flunarizine upon single drop application. Albino rabbits were used and tissue samples were collected at 15, 30, 60, 120 and 240 min after instillation. Drug concentrations in ocular tissues and plasma were measured by gas chromatography assay. After single dose application peak levels of drug were achieved at 15 min in cornea and at 30 min in aqueous humor, iris-ciliary body and retina. Unilateral topical flunarizine caused a significant reduction of intraocular pressure in rabbits. The pharmacokinetic profile showed a good ocular bioavailability of the drug providing that the new topical formulation containing 0.05% flunarizine reach the target tissues at effective concentrations and therefore may be use in the treatment of glaucoma.

Effects of cloricromene, a coumarin derivative, on endotoxin-induced uveitis in Lewis rats

PURPOSE

To investigate the effects of cloricromene, a coumarin derivative, in rats subjected to endotoxin-induced uveitis (EIU).

METHODS

Endotoxin uveitis was induced in male Lewis rats by a single footpad injection of 200 microg lipopolysaccharide (LPS). Cloricromene was topically applied to the rat eye twice at 1 hour before and 7 hours after injection of LPS. A separate group of animals was treated with vehicle. Rats were killed 16 hours after injection and the eyes enucleated for histologic examination and immunohistochemical analysis. The effect of treatment was also evaluated by slit lamp examination, by the number of intraocular inflammatory cells on histologic sections, and by measuring the protein and TNFalpha levels in the aqueous humor. Nitrite and nitrate production was also measured in the aqueous humor.

RESULTS

The histopathology of the iris-ciliary body included inflammatory cell infiltration and nuclear modification of vessel endothelial cells. Cloricromene treatment reduced the inflammatory cell infiltration and improved histologic status of the ocular tissue. Immunohistochemical analysis for P-selectin, intracellular adhesion molecule (ICAM)-1, nitrotyrosine, and poly(ADP-ribose) synthetase (PARS) revealed a positive staining in inflammatory cell infiltration from LPS-treated rats. The degree of staining for P-selectin, ICAM-1, nitrotyrosine, and PARS was markedly reduced in tissue sections obtained from LPS-recipient rats that had received cloricromene. Cloricromene strongly inhibited cell infiltration, protein exudation, TNFalpha production, and nitrite-nitrate formation.

CONCLUSIONS

This study provides the first evidence that cloricromene, a coumarin derivative, attenuates the degree of inflammation and tissue damage associated with EIU in rats.

Ocular tolerability of Eudragit RS100 and RL100 nanosuspensions as carriers for ophthalmic controlled drug delivery

Polymeric nanoparticle suspensions were prepared from inert polymer resins (Eudragit RS100, RS, and RL100, RL). When loaded with drugs, these resins have been recently proposed as delivery systems to prolong the release and improve ocular availability of the drug. To verify the absence of toxicity toward the ocular structures, blank RS and RL nanosuspensions were applied to rabbit eye and a modified Draize test was performed. Polymer nanoparticles appeared to be avoiding of any irritant effect on cornea, iris, and conjunctiva up to 24 h after application, thus appearing to be a suitable inert carrier for ophthalmic drug delivery.

Ocular hypotensive action of topical flunarizine in the rabbit: role of sigma 1 recognition sites

In a previous study we ascertained the presence of sigma1 and sigma2 recognition sites in the rabbit iris-ciliary body, an ocular structure involved in aqueous humor production and drainage. We characterized the sigma1 sites using the preferential ligand (+)-pentazocine, which caused a significant reduction of intraocular pressure (IOP). In the present study, flunarizine, a calcium channel blocker with a complex pharmacological profile, bound to sigma1 sites expressed in the iris-ciliary body with moderate affinity (K(i) = 68 nM). Unilateral topical flunarizine (0.01-0.1%) caused a dose-related reduction of IOP in ocular normotensive rabbits and in the alpha-chymotrypsin model of ocular hypertension, without altering the IOP of the contralateral eye. This activity was blocked by the sigma1 site antagonist NE-100 [N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine HCl] which, by itself, had no effect on IOP. Detection of flunarizine in rabbit iris-ciliary body homogenates, after topical instillation, showed that it adequately penetrates the rabbit eye. To investigate mechanisms that may contribute to ocular hypotension induced by sigma1 agonists, we carried out in vitro studies on the isolated rabbit iris-ciliary body. Flunarizine (IC50 = 5. 96 nM) and (+)-pentazocine (IC50 = 3. 81 nM) inhibited [3H]norepinephrine release. Moreover, flunarizine (IC50 = 6.34 nM) and (+)-pentazocine (IC50 = 27.26 nM) also antagonized isoproterenol-induced cAMP accumulation. The action of flunarizine and (+)-pentazocine was sensitive to NE-100 antagonism; however, this latter compound partially prevented their effect on [3H]norepinephrine and cAMP accumulation. These findings indicate that flunarizine and (+)-pentazocine interact with ocular sigma1 sites and may prove effective in the control of ocular hypertension.

Enhanced ocular anti-inflammatory activity of ibuprofen carried by an Eudragit RS100 nanoparticle suspension

PURPOSE

To investigate the ocular pharmacodynamic profile of a polymer nanoparticle system loaded with sodium ibuprofen (IBU-RS) in comparison to an aqueous solution of ibuprofen lysinate (IBL) in the rabbit eye both being applied topically.

METHODS

Ocular inflammation was elicited by topical application of sodium arachidonate. Inflammation was quantified according to a modified Draize test. The protein level and the number of polymorphonuclear leukocytes in the aqueous humor were assessed after 2 h from arachidonate instillation. The ibuprofen concentration in the aqueous humor was evaluated by HPLC assay. The physico-chemical properties of nanoparticles were also evaluated.

RESULTS

The IBU-RS nanosuspension formulation significantly reduced the primary signs of ocular inflammation as well as significantly reducing the protein level and the number of polymorphonuclear leukocytes in the aqueous humor compared with the IBL formulation. Furthermore, the aqueous humor drug concentration from the group treated with IBU-RS was significantly higher compared to the IBL-treated group. The IBU-RS nanosuspensions showed very interesting size and surface charge values, adequate for ophthalmic administration.

CONCLUSIONS

The pharmacological profile of the topical IBU-RS nanosuspension formulation described in this study indicates that the dispersion of the drug within RS polymer nanoparticles increased its ocular bioavailability and ultimately its pharmacological activity.

Flurbiprofen-loaded acrylate polymer nanosuspensions for ophthalmic application

Polymeric nanoparticle suspensions were prepared from Eudragit RS100R and RL100R polymer resins and loaded with flurbiprofen (FLU), with the aim at improving the availability of the drug at an intra-ocular level for the prevention of the myosis induced during extracapsular cataract surgery. Nanosuspensions were prepared by a quasi-emulsion solvent diffusion technique using different formulation parameters (drug-to-polymer ratio, initial polymer concentration, agitation speed, etc.). The resulting nanoparticles showed mean sizes around 100 nm and a fixed positive charge (zeta-potential around +40/+60 mV). Stability tests after mid-time storage (4 degrees C or room temperature) or freeze-drying were carried out to optimise a possible final pharmaceutical preparation. In vitro, dissolution tests showed a controlled release profile of FLU from the nanoparticles. In vivo anti-inflammatory efficacy was assessed in the rabbit eye after induction of an ocular trauma (paracentesis). FLU-loaded nanosuspensions did not show toxicity on ocular tissues. Moreover, an inhibition of the miotic response to the surgical trauma comparable to a control eye-drop formulation was obtained, even though an actual lower concentration of free drug in the conjunctival sac was achieved from the nanoparticle system. Drug levels in the aqueous humour were also higher after application of the nanosuspensions.

Eudragit RS100 nanosuspensions for the ophthalmic controlled delivery of ibuprofen

Topical application of non-steroidal anti-inflammatory drugs on the eye is a common treatment used to contrast the miosis induced by surgical traumas, such as cataract extraction. With the aim of improving the availability of sodium ibuprofen (IBU) at the intraocular level, IBU-loaded polymeric nanoparticle suspensions were made from inert polymer resins (Eudragit RS100). The nanosuspensions were prepared by a modification of the quasi-emulsion solvent diffusion technique using variable formulation parameters (drug-to-polymer ratio, total drug and polymer amount, stirring speed). Nanosuspensions had mean sizes around 100 nm and a positive charge (zeta-potential of +40/+60 mV), this makes them suitable for ophthalmic applications. Stability tests (up to 24 months storage at 4 degrees C or at room temperature) or freeze-drying were carried out to optimize a suitable pharmaceutical preparation. In vitro dissolution tests indicated a controlled release profile of IBU from nanoparticles. In vivo efficacy was assessed on the rabbit eye after induction of an ocular trauma (paracentesis). An inhibition of the miotic response to the surgical trauma was achieved, comparable to a control aqueous eye-drop formulation, even though a lower concentration of free drug in the conjunctival sac was reached from the nanoparticle system. Drug levels in the aqueous humour were also higher after application of the nanosuspensions; moreover, IBU-loaded nanosuspensions did not show toxicity on ocular tissues.

Rapid high-performance liquid chromatographic assay of dorzolamide in rabbit aqueous humor

A rapid high-performance liquid chromatographic method using a C(18) reversed-phase column (Hypersil ODS) with UV detection at 254 nm and a simple pre-treatment of samples is presented for the analysis of dorzolamide, a carbonic anhydrase inhibitor, in rabbit aqueous humor. A water solution containing 2% ZnSO(4) small middle dot7H(2)O was used to deproteinize aqueous humor samples. The mobile phase consisted of 7% CH(3)CN and 93% of a solution containing 1% TEA adjusted to pH = 3.5 with H(3)PO(4). Paracetamol was found to be a suitable internal standard. The standard curves were linear in the detection range. The precision and the accuracy were <5% for both intra- and inter-day assays.

Simultaneous determination of cloricromene and its active metabolite in rabbit aqueous humor by high-performance liquid chromatography

A rapid and simple method was developed for the simultaneous separation and quantification of cloricromene, a coumarine derivative, and its active metabolite, cloricromene acid, in rabbit aqueous humor. The analyses were performed by high-performance liquid chromatography using a C18 reversed-phase column (Hypersil ODS) with UV detection at 318 nm. The mobile phase consisted of acetonitrile-water containing 1% triethylamine pH 3.5, adjusted with orthophosphoric acid. An acetonitrile gradient was necessary to achieve good separation within 13 min. Timolol was found to be a suitable internal standard. The retention times ranged from 5.72 to 11.25 min. A simple pre-treatment with acetonitrile containing 0.6% HCIO4 was used to deproteinize aqueous humor samples. The limit of quantitation ranged between 10 and 20 ng/ml. The recovery was >90%. The relationship between peak areas and concentration was linear over the range between 0.01 and 3.8 microg/ml, with r2 > 0.99. The assay provided good reproducibility and accuracy for both analytes and proved to be suitable for pharmacokinetic studies of cloricromene.

Pharmacological profile of oxaprozin eye drops

The effects of eye drops containing a propionic acid derivative (oxaprozin) at 0.1% concentration on ocular inflammation produced by sodium arachidonate in the rabbit's eye were evaluated. Furthermore, the aqueous bioavailability of the drug formulation in the uninflamed and inflamed eyes was evaluated. Oxaprozin eye drops significantly reduced the signs of ocular inflammation elicited by sodium arachidonate on conjunctiva and iris. Oxaprozin treatment significantly reduced the levels of polymorphonuclear leukocytes and protein concentration in aqueous samples obtained from the eyes treated with arachidonate. Present data suggest, for the first time, that oxaprozin may be employed topically to prevent ocular reactions where the arachidonic acid cascade is activated.

Ocular tolerability and in vivo bioavailability of poly(ethylene glycol) (PEG)-coated polyethyl-2-cyanoacrylate nanosphere-encapsulated acyclovir

Acyclovir-loaded polyethyl-2-cyanoacrylate (PECA) nanospheres were prepared by an emulsion polymerization process in the micellar phase and characterized. The influence of the presence of nonionic surfactant as well as other substances [i.e., 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CyD) and poly(ethylene glycol) (PEG)], on formulation parameters and loading capacity was investigated. In particular, the presence of PEG resulted in an increase of mean size and size distribution. To obtain PEG-coated PECA nanospheres with a mean size of < 200 nm, Pluronic F68 at concentrations > 1.5% (w/v) should be used during preparation. The presence of PEG also resulted in a change in zeta potential, from -25.9 mV for uncoated nanospheres to -12.2 mV for PEG-coated PECA nanospheres. The presence of HP-beta-CyD elicited an increase of nanosphere size and size distribution, but zeta potential was not influenced. In vitro drug release from nanospheres was determined in both phosphate buffer (pH 7.4) and plasma. The presence of HP-beta-CyD and PEG did not influence the acyclovir release rate in plasma. In the case of release in phosphate buffer, PEG-coated nanospheres showed a slower release. Ocular tolerability of PEG-coated PECA nanospheres was evaluated by the in vivo Draize test. This colloidal carrier was well tolerated, eliciting no particular inflammation at the level of the various ocular structures. In vivo ocular bioavailability was evaluated by instilling 50 microL of the acyclovir-loaded nanospheres only once in the conjunctival sac of rabbit eyes. At various time intervals, aqueous humour acyclovir content was determined by high-performance liquid chromatography. Acyclovir-loaded PEG-coated PECA nanospheres were compared with an aqueous solution of the drug and a physical mixture of acyclovir nanospheres. The acyclovir-loaded PEG-coated PECA nanospheres showed a significant (p < 0.001) increase of drug levels (25-fold) in aqueous humor compared with the free drug or the physical mixture. This finding is probably due to an improved ocular mucoadhesion of PEG-coated PECA nanospheres.

Biocompatibility and biodegradation of intravitreal hyaluronan implants in rabbits

To study the biocompatibility and the biodegradation rate in vivo of new intravitreal implants made with three different hyaluronic acid esters: Hyaff7, Hyaff11 and Hyaff11p75 (100% ethyl ester, 100 and 75% benzyl esters, respectively), the plugs were implanted through a sclerotomy at 3.5 mm from the limbus of rabbit eyes. In order to evaluate the in vivo biodegradation the shaft diameter of the plugs was measured by ultrasound biomicroscopy. Slit lamp microscopy, ophthalmoscopy and ERG were performed periodically. The effects of the implants on ocular tissues were also evaluated histologically. All the plugs showed a good biocompatibilitv. Plugs of both the total esters, Hyaff7 and Hyaff11, were found to undergo a slow dissolution process for 60 and 150 days, respectively. The partial benzyl ester, Hyaff11p75, was completely reabsorbed after 15 days. Analysis of variance showed a high correlation between biodegradation rate and the time of resorption (F = 90.5; p < 0.001). The biodegradation rate of each implant is related to the chemical structure of the three types of Hyaff (F = 4.51; p = 0.005). The present data suggest that intravitreal implants based on hyaluronic acid esters represent useful biocompatible and biodegradable devices for a potential drug delivery system in the treatment of posterior segment ocular diseases.

Pharmacological evaluation of a new timolol/pilocarpine formulation

A new formulation (HYA) based on timolol hyaluronate and pilocarpine hyaluronate salts has been shown to improve the bioavailability of the drugs and to extend the duration of their action. Extent of the intraocular pressure lowering effect, duration of action and aqueous bioavailability of timolol and pilocarpine of HYA were compared with a commercial preparation. Ocular hypertension in the rabbit was induced by alpha-chymotrypsin or by water loading. The hypotensive effect of HYA treatment was significantly greater and longer than that observed in rabbit eyes treated with the commercial preparation both in the normotensive and in the hypertensive animals. Furthermore, we evaluated the miotic response; due to pilocarpine, normotensive rabbits showed a greater miotic response and an extended duration when the eyes were treated with HYA. The new formulation increased the aqueous availability of timolol and pilocarpine compared to the commercial preparation as determined by HPLC. The pharmacodynamic and pharmacokinetic profiles of HYA indicate an increase in efficacy and duration of action along with an increase in bioavailability of timolol and pilocarpine in comparison with the commercial preparation.

Pharmacological profile of a new topical pilocarpine formulation

A new formulation based on pilocarpine hyaluronate salt has been shown to improve the bioavailability of the drug and to extend the duration of activity. We evaluated the extent of intraocular pressure reduction, the duration of action and the kinetics of miotic response of this formulation in comparison with a commercial preparation with the same drug concentration. Ocular hypertension in the rabbit was induced by alpha-chymotrypsin or by water loading. The hypotensive effect of the new formulation treatment was significantly greater and longer than that observed in rabbit eyes treated with the commercial preparation both in the normotensive and in the hypertensive animals. Furthermore, we evaluated the miotic response in normotensive rabbits showing a greater miotic response and an extended duration when the eyes were treated with the new formulation. The pharmacological profile of the new formulation described in this study indicates an increase of efficacy and duration of action compared to the commercial preparation.

Sigma1 recognition sites in rabbit iris-ciliary body: topical sigma1-site agonists lower intraocular pressure

In this study, we examined the presence of sigma1 and sigma2 sites in the rabbit iris-ciliary body by receptor binding and investigated their effects on intraocular pressure (IOP) in albino rabbits. The iris-ciliary body has binding sites for the sigma1-site agonist [3H](+)-pentazocine (Kd = 4.6 nM; Bmax = 212 fmol/mg protein) and sigma2 sites labeled with [3H]1,3-di-o-tolylguanidine (DTG) (Kd = 8. 2 nM; Bmax = 1120 fmol/mg protein). In competition binding studies, (+)-pentazocine and the sigma antagonist NE-100 displayed high affinity for sigma1 sites (Ki = 2.1 and 2.4 nM, respectively), whereas (+)-N-allylnormetazocine (NANM) was less potent (Ki = 178 nM). Unilateral topical (+)-pentazocine (0.01-0.1%) caused a significant dose-related reduction of IOP in ocular normotensive rabbits and in the alpha-chymotrypsin model of ocular hypertension. (+)-NANM was less potent than (+)-pentazocine. Neither compound altered the IOP of the contralateral eye, and their hypotensive activity was blocked by NE-100 that, by itself, had no effect on IOP. (-)-Pentazocine, (-)-NANM, and DTG had no effect on IOP. DTG prevented the hypotensive effect of (+)-pentazocine, suggesting that it acts as a sigma1-site antagonist. sigma-Site ligands did not affect pupil diameter or cause ocular inflammation. Topical [3H](+)-pentazocine reaches the intraocular tissues within 30 min, and its uptake in the iris-ciliary body and retina was significantly reduced by topical pretreatment with NE-100, as expected for a receptor-specific agent. Reverse-phase HPLC confirmed the presence of intact (+)-pentazocine in iris-ciliary body homogenates. sigma1-Site agonists may offer a novel class of agents potentially effective in the control of ocular hypertension.

Characterization and in-vivo ocular absorption of liposome-encapsulated acyclovir

The potential of liposomes as an in-vivo ophthalmic drug delivery system for acyclovir was investigated. The drug-membrane interaction was evaluated by means of differential scanning calorimetry analysis. These experiments showed that acyclovir is able to interact with both positively and negatively charged membranes via electrostatic or hydrogen bonds. No interaction was observed with neutral membranes made up of dipalmitoylphosphatidylcholine. Different liposome preparation procedures were carried out to encapsulate acyclovir. The drug encapsulation mainly depends on the amount of water which the liposome system is able to entrap. In the case of multilamellar vesicles, charged systems showed the highest encapsulation efficiency. No particular difference in the encapsulation efficiency was observed for oligolamellar vesicles prepared with the reverse-phase evaporation technique. Oligolamellar liposomes showed the highest acyclovir encapsulation parameters and had release profiles similar to those of multilamellar liposomes. In-vivo experiments using male New Zealand albino rabbits were carried out to evaluate the aqueous humour concentration of acyclovir bioavailability. The most suitable ophthalmic drug delivery system was oligolamellar systems made up of dipalmitoylphosphatidylcholine-cholesterol-dimethyldioctadecyl glycerole bromide (7:4:1 molar ratio), which presented the highest encapsulation capacity and were able to deliver greater amounts of the drug into the aqueous humour than a saline acyclovir solution or a physical liposome/drug blend.

Pharmacological evaluation of anti-inflammatory pyrrole-acetic acid derivative eye drops

The effects of mucoadhesive eye drops containing a pyrrole-acetic acid derivative (tolmetin) at 0.5% concentration on ocular inflammation produced by sodium arachidonate in the rabbit's eye were evaluated. Furthermore, the bioavailability of the mucoadhesive formulation in the aqueous humor against an aqueous-based solution was compared. Tolmetin eye drops significantly reduced the signs of ocular inflammation elicited by sodium arachidonate on conjunctiva and iris. Tolmetin treatment significantly reduced the levels of prostaglandin E2, polymorphonuclear leukocytes and protein concentration in aqueous samples obtained from the eyes treated with arachidonate. The de novo production of prostaglandin E2 by corneas obtained from rabbits sacrificed 2 hours after arachidonate instillation were significantly higher in samples taken from controls than in corneas obtained from the eyes treated with tolmetin eye drops. Furthermore, the drug treatment significantly reduced the rise in intraocular pressure arachidonate-induced. The mucoadhesive formulation showed a higher bioavailability in aqueous humor compared to the aqueous-based solution both in the uninflamed and in the inflamed rabbit eyes.

Methylprednisolone delivery by Hyalobend corneal shields and its effects on rabbit ocular inflammation

Release of methylprednisolone from hyaluronic acid derivative corneal shields (Hyalobend), in vitro and in vivo, was evaluated as well as ocular anti-inflammatory activity in the rabbit eye. The release of methylprednisolone from Hyalobend corneal shields in vitro followed zero-order kinetics. After placing Hyalobend corneal shields in rabbit eye, aqueous and tear fluid methylprednisolone levels were detected up to 48 hours and compared with the levels obtained with methylprednisolone suspension. Hyalobend corneal shields maintained almost constant methylprednisolone levels in the rabbit tear fluid. On the contrary, the suspension gave very high tear values of steroid concentrations in the first 30 minutes but undetectable in less than 200 minutes. Hyalobend corneal shields ensured effective levels of methylprednisolone into the rabbit aqueous for up to 48 hours. Aqueous levels of drug, in the group treated with the suspension, decreased progressively and after 480 minutes were undetectable. Hyalobend corneal shields significantly reduced the conjunctival inflammation elicited by sodium arachidonate compared with control. Furthermore, Hyalobend corneal shields treatment significantly reduced the levels of PGE2 in the tear fluid. Hyalobend corneal shields increase the residence time of methylprednisolone in rabbit tear fluid and enhance the penetration into the aqueous humor as well as reduced the primary signs of ocular inflammation.

Effect of sodium naproxen on inflammatory response induced by anterior chamber paracentesis in the rabbit

This study evaluated the effect of sodium naproxen (a reversible competitive inhibitor of cyclo-oxygenase) and phenylephrine (a mydriatic alpha-adrenergic agent) eye drops in maintaining atropine mydriasis in the rabbit after paracentesis. Moreover, to assess the influence of these treatments on vascular and cellular inflammatory responses in the rabbit eye, several biochemical parameters were considered. Anterior chamber paracentesis significantly reduced atropine-induced mydriasis and a parallel elevation of proteins, polymorphonuclear leucocytes (PMNs), prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) levels in the secondary aqueous humour (obtained 120 min later) was observed. A significant increase in PMNs in the aqueous humour and a parallel increase in myeloperoxidase activity, a measure of PMN infiltration, in the iris-ciliary body were detected. Atropine-induced mydriasis was maintained in rabbits treated with either sodium naproxen or phenylephrine eye drops. However, only in the former group were the inflammatory parameters significantly reduced, with the exception of aqueous LTB4 levels. The inhibition of the protein influx in the aqueous humour and of the miosis produced by sodium naproxen can be related to the high drug levels in the aqueous humour that were effective in inhibiting the cyclo-oxygenase pathway of arachidonic acid metabolism, whereas the effects on PMN infiltration appear to be independent of significant release of the potent chemotactic agent LTB4, synthesized via the 5-lipoxygenase pathway.

The effect of ganglioside on oxidation-induced permeability changes in lens and in epithelial cells of lens and retina

Several recent reports have indicated that ganglioside treatment both in vivo and in vitro has a protective effect on the loss of membrane permeability resulting from inhibition of transport enzyme(s) in different experimental models. In this study we have investigated the effect of monosialoganglioside on oxidation-induced changes in organ-cultured rabbit lenses and in cultured dog lens epithelium and human retinal pigment epithelial cells. Exposure of organ-cultured lenses to 0.5 mM hydrogen peroxide for 1 hr increased the efflux of 86Rb from intact lenses and loss of myoinositol from the capsule epithelium. Pretreatment of the lenses with monosialoganglioside significantly reduced the efflux rate of 86Rb and loss of myoinositol. Monosialoganglioside also prevented morphological changes induced by 0.1 mM hydrogen peroxide in dog lens epithelium and loss of cell viability caused by docosahexaenoic acid in dog lens epithelium and in human retinal pigment epithelial cells. In contrast to the protective effect of monosialoganglioside on permeability and morphological changes in cultured cells, it had no effect against single-strand breaks of DNA in dog lens epithelium resulting from exposure to hydrogen peroxide, X-ray and UV-B radiation. Although the molecular mechanisms by which monosialoganglioside prevents permeability and morphological changes induced by hydrogen peroxide and docosahexaenoic acid are not known, it appears that this ganglioside serves as a membrane stabilizer rather than as a free-radical scavenger.

Effects of Mipragoside on ocular allergic inflammation in the rabbit

We evaluated the pharmacodynamic and pharmacokinetic profile of Mipragoside, a monosialoganglioside isopropyl-ester (as 0.5% w/w ophthalmic gel), on allergic inflammation of the eye induced by reverse passive Arthus reaction, on a non-immune mast cell degranulation elicited by compound 48/80 and on ocular inflammation produced by horse serum. Conjunctiva was sensitized by injection of rabbit antisera to bovine proteins and the allergic conjunctivitis was triggered by intravenous administration of bovine gamma globulin. The permeability of the blood-conjunctival barrier was evaluated by a fluorometric method. Compound 48/80 was topically administered at concentration of 50mg/ml and histological analysis of conjunctiva was performed. Horse serum was administered by intravenous injection at different days. The pharmacokinetic profile of topical 3H-Mipragoside on 48/80 model was investigated and compared with untreated animals. Mipragoside treatment significantly reduced (p < 0.05 vs placebo) the conjunctival vasopermeability induced by reverse passive Arthus reaction as well as successfully reduced the eosinophil levels in the conjunctival epithelium (p < 0.01 vs placebo) elicited by compound 48/80. Further, Mipragoside successfully reduced the primary signs of ocular inflammation produced by horse serum administration. A radiotracer technique was used to evaluate the disposition of 3H-Mipragoside in the rabbit ocular tissues. Disposition of the drug was monitored at 30, 60, 120 and 240 min. 3H-Mipragoside levels in the inflamed conjunctiva were significantly higher (p < 0.01) than in the control eye.

Effects of sodium naproxen eye drops on rabbit ocular inflammation induced by sodium arachidonate

Sodium naproxen, a reversible competitive inhibitor of cyclooxygenase, is widely used as an anti-inflammatory agent in clinical practice. The purpose of this study was to determine whether eye drops containing 0.5% (w/v) sodium naproxen reduce a number of inflammatory responses produced by sodium arachidonate in the rabbit's eye. Sodium naproxen eye drops successfully reduced the primary signs of ocular inflammation elicited by 0.5% sodium arachidonate on conjunctiva and iris. However, the drug was less effective in reducing conjunctival inflammation induced by 1% sodium arachidonate. Sodium naproxen treatment significantly reduced the levels of prostaglandin E2 (PGE2), polymorphonuclear leukocytes and protein concentration in aqueous humor samples obtained from the eyes of rabbits treated with 0.5% sodium arachidonate whereas aqueous humor levels of leukotriene B4(LTB4) were not found significantly different from control rabbits. Interestingly, PGE2 as well as LTB 4 "de novo" production by corneas and lenses obtained from rabbits sacrificed 2 h after arachidonate and incubation "in vitro" for 20 min were significantly higher in samples taken from controls than in tissues obtained from the eyes treated with sodium naproxen eye drops. Finally, this drug treatment significantly antagonized the rise in intraocular pressure induced by 0.5% sodium arachidonate. Present data suggest that sodium naproxen may be employed topically to prevent ocular inflammatory reactions where the arachidonic acid cascade is activated.

Fluctuation of serum complement levels in children with neuroblastoma

Serum samples from eleven children with neuroblastoma were drawn at diagnosis and again every 15 days or a month after the beginning of treatment over the course of 17 months observation. Twenty healthy children of the same age with no appreciable clinical manifestation were also studied as controls. Investigations included quantitative serum complement levels (total complement hemolytic activity, C3 and C4), anticomplementary serum activity and urine catecholamine levels (VMA and HVA). Complement levels of tumor patients were significantly higher than those of healthy subjects, but fluctuations were seen at different stages of the disease; patients at admission with active tumors or tumor recurrence had higher complement levels than those of patients in remission. Temporary recurrences of the disease were usually accompanied by fluctuations of urinary catecholamines, serum complement levels (mainly C3) and anticomplementary serum activity. At the terminal phase of the disease a drop in complement levels was usually seen, while urinary catecholamines were progressively increasing.