Preparation of highly monodisperse W/O emulsions with hydrophobically modified SPG membranes

Experimental investigations on the hydrophobic modification of SPG membranes and the preparation of monodisperse W/O (water-in-oil) emulsions using the modified membranes were carried out. Effects of the osmotic pressure of disperse phase, the average pore size of membranes, emulsifier concentrations in continuous phase and the transmembrane pressure on the average size, size distribution and size dispersion coefficient of emulsions were systematically studied. The stability of W/O emulsions was also investigated. The results showed that SPG membranes took on excellent hydrophobicity through the modification by silane coupler reagent (octyltriethoxysilane) or by silicone resin (polymethylsilsesquioxane). Monodisperse W/O emulsions with size dispersion coefficient of about 0.25, which meant high monodispersity, were successfully prepared by using the hydrophobically modified SPG membranes with average pore sizes of 1.8, 2.0, 2.5, 4.8 and 11.1 microm. When the osmotic pressure was lower than 0.855 MPa, the average size of emulsions was gradually increased while the size dispersion coefficient delta gradually decreased with the osmotic pressure; when the osmotic pressure was higher than 0.855 MPa, both the coefficients kept unvarying. When kerosene was saturated with disperse phase in advance, the average size of emulsions became larger and the monodispersity of emulsions was slightly better than that prepared using unsaturated kerosene. The smaller the pore size of SPG membranes was, the better the monodispersity of the W/O emulsions. The average size and size dispersion coefficient delta were nearly independent on the emulsifier concentrations when the PGPR concentration was in the range from 0.5 to 5.0 wt%, whereas both of them slightly increased as the PGPR concentration was below 0.5 wt%. The effect of the transmembrane pressure on size distributions was slight. Both the average size and size dispersion coefficient delta slightly increased to some extent with the increase of the transmembrane pressure in the experimental range. The stability of the W/O emulsions was dependent on the storage time. The mean size of W/O emulsions decreased gradually with the increase of storage time at the first 35 days, and then kept constant; while the size dispersion coefficient of W/O emulsions was nearly not changed.

Preparation of submicrometer-sized monodispersed thermoresponsive core-shell hydrogel microspheres

We have successfully prepared monodispersed thermoresponsive core-shell hydrogel microspheres with a mean diameter of 200-400 nm with poly(N-isopropylacrylamide-co-styrene) [P(NIPAM-co-St)] cores and poly(N-isopropylacrylamide) (PNIPAM) shells. The submicrometer-sized monodispersed P(NIPAM-co-St) core seeds were prepared by using a surfactant-free emulsion polymerization method, and the PNIPAM shell layers were fabricated onto the core seeds by using a seed polymerization method. The particle size, morphology and monodispersity, and thermoresponsive characteristics of the prepared microspheres were experimentally studied. In the preparation of P(NIPAM-co-St) seeds, with increasing the initiator dosage, the mean diameters and the dispersal coefficients were almost at the same levels at first; however, when the initiator dosage increased further to a critical amount, the mean diameters decreased drastically and the monodispersity became worse significantly. With increasing the stirring rate, the particle diameter decreased, and when the stirring rate was larger than 600 rpm, the monodispersity became worse obviously. With increasing the phase ratio, the mean diameter became larger simply, and the monodispersity became worse first and then became better again. With increasing the reaction time, the particle sizes nearly did not change, while the monodispersity gradually became better slightly. For the core-shell microspheres, with increasing the NIPAM dosage in the preparation of the PNIPAM shell layers, the mean diameters became larger simply, the monodispersity became better, and the thermoresponsive swelling ratio of the hydrodynamic diameters increased.

Phase I and pharmacokinetic study of irinotecan in combination with R115777, a farnesyl protein transferase inhibitor

The aims of this study were to determine the maximum-tolerated dose (MTD), toxicity profile, and pharmacokinetics of irinotecan given with oral R115777 (tipifarnib), a farnesyl protein transferase inhibitor. Patients were treated with escalating doses of irinotecan with interval-modulated dosing of R115777 (continuously or on days 1–14, and repeated every 21 days). In total, 35 patients were entered onto the trial for a median duration of treatment of 43 days (range, 5–224 days). Neutropenia and thrombocytopenia were the dose-limiting toxicities; other side effects were mostly mild. The MTD was established at R115777 300 mg b.i.d. for 14 consecutive days with irinotecan 350 mg m⁻² given every 3 weeks starting on day 1. Three patients had a partial response and 14 had stable disease. In the continuous schedule, the area under the curves of irinotecan and its active metabolite SN-38 were 20.0% (P=0.004) and 38.0% (P<0.001) increased by R115777, respectively. Intermittent dosing of R115777 at a dose of 300 mg b.i.d. for 14 days every 3 weeks is the recommended dose of R115777 in combination with the recommended single-agent irinotecan dose of 350 mg m⁻².

Benzodioxocin-3-ones and N-acyl-3-amino-3-buten-2-ones: novel classes of cathepsin K cysteine protease inhibitors

The design, synthesis, enzymologic, and protein mass spectrometric characterization of benzodioxocin-3-one and N-acyl-3-amino-3-buten-2-one inhibitors of the cysteine protease cathepsin K are described. The benzodioxocin-3-one ring system is chemically unstable giving rise to a mixture of N-acyl-3-amino-3-buten-2-one and hemiketals. This mixture of N-acyl-3-amino-3-buten-2-one and hemiketals potently inhibits recombinant, human cathepsin K (IC50 = 36 nM) by a time-independent, irreversible mechanism. Formation of a covalent adduct between cathepsin K and inhibitor has been confirmed by mass spectrometry.

Study of SPG membrane emulsification processes for the preparation of monodisperse core-shell microcapsules

Experimental investigations on the Shirasu-porous-glass (SPG)-membrane emulsification processes for preparing monodisperse core-shell microcapsules with porous membranes were carried out systematically. The results showed that, to get monodisperse oil-in-water (O/W) emulsions by SPG membrane emulsification, it was more important to choose an anionic surfactant than to consider hydrophile-lipophile balance (HLB) matching. Increasing the viscosity of either the disperse phase or the continuous phase or decreasing the solubility of the disperse phase in the continuous phase could improve both the monodispersity and the stability of emulsions. With increasing monomer concentration inside the disperse phase, the monodispersity of emulsions became slightly worse and the mean diameter of emulsions gradually became smaller. Monodisperse monomer-containing emulsions were obtained when the SPG membrane pore size was larger than 1.0 micro m, and from these emulsions satisfactory monodisperse core-shell microcapsules with a porous membrane were prepared. On the other hand, when the SPG membrane pore size was smaller than 1.0 mciro m, no monodisperse emulsions were obtained because of the formation and chokage of solid monomer crystals in the pores or at the end of the pores of the SPG membrane. This was due to the remarkable solvation and diffusion of the solvent in water. With increasing the emulsification time the average emulsion diameter generally decreased, and the monodispersity of the emulsions gradually became worse.

Highly toxic and broad-spectrum insecticidal Bacillus thuringiensis engineered by using the transposon Tn917 and protoplast fusion

The chromosome of the Bacillus thuringiensis strain S184 that was toxic against the third instar larvae of Spodoptera litura with the LC(50) of 9.74 microg/ml was successfully integrated into two genes of cyt1Aa and cry11Aa using the transposon Tn917, yielding the primary engineered strain TnX. The strain TnX was highly toxic to the third instar larvae of Culex pipiens fatigans with the LC(50) of 5.12 ng/ml which was 1.82-fold higher than that of B. thuringiensis subsp. israelensis, but lowly toxic to lepidopterous larvae. By the protoplast fusion of the strain TnX and the strain S184-Tet(r) (resistance to tetracycline), the target engineered strain TnY was obtained. Against the third instar larvae of S. litura, the strain TnY LC(50) was of 4.68 micro g/ml and increased by 2.08-fold in comparison with the parent strain S184. Against the third instar larvae of C. pipiens fatigans, the strain TnY LC(50) was of 103.20 ng/ml. The two target genes of cyt1Aa and cry11Aa integrated into the chromosome were extremely stable and had little possibility of a second transposition. It was unclear whether some factors existing in the parent strain, S184, contributed to the high toxicity of the strains TnX and TnY.

The cell cycle control element of histone H4 gene transcription is maximally responsive to interferon regulatory factor pairs IRF-1/IRF-3 and IRF-1/IRF-7

Interferon regulatory factors (IRFs) are transcriptional mediators of interferon-responsive signaling pathways that are involved in antiviral defense, immune response, and cell growth regulation. To investigate the role of IRF proteins in the regulation of histone H4 gene transcription, we compared the transcriptional contributions of IRF-1, IRF-2, IRF-3, and IRF-7 using transient transfection assays with H4 promoter/luciferase (Luc) reporter genes. These IRF proteins up-regulate reporter gene expression but IRF-1, IRF-3, and IRF-7 are more potent activators of the H4 promoter than IRF-2. Forced expression of different IRF combinations reveals that IRF-2 reduces IRF-1 or IRF-3 dependent activation, but does not affect IRF-7 function. Thus, IRF-2 may have a dual function in histone H4 gene transcription by acting as a weak activator at low dosage and a competitive inhibitor of other strongly activating IRFs at high levels. IRF-1/IRF-3 and IRF-1/IRF-7 pairs each mediate the highest levels of site II-dependent promoter activity and can up-regulate transcription by 120-150-fold. We also find that interferon gamma up-regulates IRF-1 and site II-dependent promoter activity. This up-regulation is not observed when the IRF site is mutated or if cells are preloaded with IRF-1. Our results indicate that IRF-1, IRF-2, IRF-3, and IRF-7 can all regulate histone H4 gene expression. The pairwise utilization of distinct IRF factors provides a flexible transcriptional mechanism for integration of diverse growth-related signaling pathways.

[AFLP markers of restoring genes of the wild-abortive hybrid rice]

Fertile and sterile pools were set up by bulked segregant analysis (BSA) based on the selection for the highly fertile and highly sterile plants of Shanyou 63 F2 population. The AFLP analysis of the two pools indicated that 64 primer combinations amplified 3,477 stable and clear bands. Exception of the combination E-AGC/M-CAA, all primer combinations had not detected polymorphism between the two pools. It was proved by investigation of two parents, individuals of F2 segregant population, backbone sterile lines and restorer lines that the polymorphic fragment AP1 generated from the primer E-AGC/M-CAA was associated with the restoring gene. AP1 was a single copy detected by Southern blot hybridization. The distance between AP1 and the restoring gene was 4.76 cM.

[Detection of viral aetiology in cerebral spinal fluid samples from 580 clinical cases]

OBJECTIVE

To investigate the viral aetiology in cerebral spinal fluid (Csf) from 580 cases of CNS infection or FUO in Yuedong district from 1990 to 1997.

METHODS

Virus isolation was done with Hep-2 and BHK-21 cells.

RESULTS

21 virus types of 5 kinds of viruses were isolated from 113 samples (19.5%). Clinically diagnosed diseases included viral encephalitis 17.8% (43/242), intracranial infection 20.2% (47/233), paralytic diseases 24.3% (9/37), FUO 37.5% (9/24), convulsion 16.0% (4/25), Guillain-Barre syndrome 5.3% (1/19). Virus infection included 11 cases of Poliovirus (constitutional ratio 0.0973, including 1 Polio-I, 8 Polio-II, 2 Polio-III); 54 cases of Coxsackie virus (0.477 9, including 11 CoxA24, 10 CoxBl, 2 Cox134, 3 CoxB5); 15 cases of ECHO virus (0.1327, including 4 ECHO-24, 3 ECRO-7, 2 ECHO-12 and each one of ECHO-3, 11,14,15,27,32); 25 cases of Enterovirus (0.2213, including 14 EV-70, 11 EV-71); 8 cases of Adenovirus (0.070 8, including 3 Adv-2, 3 Adv-3 and 2 Adv7). Results of different age groups indicated there was significant difference (P < 0.05) in virus detection rate in two age groups. Virus positive rates in different years were 1990-1991 14.2% (15/106), 1992-1993 14.1%(23/163), 1994-1995 26.1% (36/138), 1996-1997 22.5% (39/173), that showed a significant difference (P <0.05).

CONCLUSIONS

Virus infection rate of CNS diseases and FUO showed an a ascending trend, and the different virus types and kinds were isolated in different periods.

[Insulin secretion and resistance during pregnancy in women with glucose intolerance]

OBJECTIVE

To investigate whether insulin secretion and resistance are different in glucose tolerant and intolerant women with normal pre-pregnant body mass index (BMI) during late pregnancy and to find out if there is association between gestational diabetes and insulin resistance syndrome.

METHODS

On the basis of a 4-hour oral glucose tolerance test (OGTT), 32 gestational diabetes mellitus (GDM) patients, 21 gestational impaired glucose tolerant (GIGT) patients, and 50 normal glucose tolerant (NGT) cases were selected from uncomplicated pregnant women. Those had normal pre-pregnant BMI who had a 1-hour 50-g glucose-screening test (> or = 7.2 mmol/L), performed between 24-28 weeks of gestation. During the OGTT, several indexes of insulin resistance, insulin secretion, lipid metabolism were measured in addition to the standard glucose measurements.

RESULTS

Glucose area under curve (GAUC), insulin area under curve (IAUC), insulin sensitivity index (ISI) transformed to natural logarithm and triglycerides (TG) are all significantly higher (P < 0.05) in GDM women. The means of these indexes in GDM group are 26.3 mmol/L.h-1, 276.5 mU/L.h-1, 4.2 and 3.2 mmol/L, respeetively. On the other hand, however, the differences of these indexes (except TG) between GIGT and NGT women are not statistically significant. The ratio of IAUC/GAUC has an increasing trend from GDM group, GIGT group to NGT group (10.5, 11.4 and 11.7, respectively), but the difference is not statistically significant. Multiple correlation coefficient study demonstrated that ISI is significantly positively correlated with GAUC, IAUC and TG (P < 0.01).

CONCLUSIONS

Compared with NGT women, GDM women has impaired insulin secretion, abnormally increased insulin resistance, and relatively dyslipidemia. GDM seems to be a component of the syndrome of insulin resistance that provides an excellent model for study and prevention in a relatively young aged group.

Effects of a calcimimetic compound and naturally activating mutations on the human Ca2+ receptor and on Ca2+ receptor/metabotropic glutamate chimeric receptors

Naturally occurring mutations identified in subjects with autosomal dominant hypocalcemia (ADH) and the calcimimetic compound, R-568, have both been reported to increase Ca2+ sensitivity of the Ca2+ receptor (CaR). To gain insight into their mechanism of action, we studied interactions between four different ADH mutations located in the amino-terminal extracellular domain (ECD) and R-568. We found that R-568 increased the sensitivity of three of the ADH mutant receptors, but the Leu125Pro mutant appeared to be maximally left-shifted in that neither R-568 addition nor combining other ADH mutations with Leu125Pro gave increases in sensitivity comparable to those seen with the three other ADH mutations studied. We also made use of truncation and deletion mutants of the CaR and CaR/metabotropic glutamate receptor type 1 (mGluR1) chimeras to study both the site of action of R-568 and the effect of the Leu125Pro activating mutation. R-568 was effective in receptor constructs containing the seven transmembrane domain (7TM) of the CaR, but not in those containing the mGluR1 7TM. R-568, moreover, imparted Ca2+ responsiveness to CaR constructs lacking all or part of the CaR ECD. The Leu125Pro mutation in contrast conferred no or minimal increase in Ca2+ responsiveness to CaR constructs lacking part of the CaR ECD but showed a striking increase in basal activity in the context of chimeras containing an mGluR1 7TM. Our results localize the site of action of NPS-568 specifically to the CaR 7TM. Our results with the Leu125Pro mutant, furthermore, suggest that the mGluR1 7TM domain may be more permissive for activation than the 7TM domain of the CaR.

A novel pharmacological approach to treating cardiac ischemia. Binary conjugates of A1 and A3 adenosine receptor agonists

Adenosine released during cardiac ischemia exerts a potent, protective effect in the heart via activation of A(1) or A(3) receptors. However, the interaction between the two cardioprotective adenosine receptors and the question of which receptor is the more important anti-ischemic receptor remain largely unexplored. The objective of this study was to test the hypothesis that activation of both receptors exerted a cardioprotective effect that was significantly greater than activation of either receptor individually. This was accomplished by using a novel design in which new binary conjugates of adenosine A(1) and A(3) receptor agonists were synthesized and tested in a novel cardiac myocyte model of adenosine-elicited cardioprotection. Binary drugs having mixed selectivity for both A(1) and A(3) receptors were created through the covalent linking of functionalized congeners of adenosine agonists, each being selective for either the A(1) or A(3) receptor subtype. MRS 1740 and MRS 1741, thiourea-linked, regioisomers of a binary conjugate, were highly potent and selective in radioligand binding assays for A(1) and A(3) receptors (K(i) values of 0.7-3.5 nm) versus A(2A) receptors. The myocyte models utilized cultured chick embryo cells, either ventricular cells expressing native adenosine A(1) and A(3) receptors, or engineered atrial cells, in which either human A(3) receptors alone or both human A(1) and A(3) receptors were expressed. The binary agonist MRS 1741 coactivated A(1) and A(3) receptors simultaneously, with full cardioprotection (EC(50) approximately 0.1 nm) dependent on expression of both receptors. Thus, co-activation of both adenosine A(1) and A(3) receptors by the binary A(1)/A(3) agonists represents a novel general cardioprotective approach for the treatment of myocardial ischemia.

[Establishment and application of Z-HL16C cell line]

OBJECTIVE

Human embryonic lung fibroblasts at 8th passage was presented to us by the Institute of Virology. At its 16th passage,under the culture condition of our laboratory, the lung fibroblasts changed into epithelial like cells. We attempted to establish a cell line and applied it for virus isolation.

METHODS

The cells were continuously passaged, cloned, the cell morphology, growth capacity and chromosome number were determined.

RESULTS

The cell size appeared uniform, cell boundary was distinct, the cell recovery rate after frozen storing was above 90%. The cell replicated permanently and now it has been passaged 136 times. The chromosome number has changed from 46 to 110. We named this cell line the ZHL16C. It proved to be sensitive to these viruses tested: enteroviruses (Polio, Cox, Echo), influenza viruses, parainfluenza viruses, adenoviruses, measles virus, herpes simplex and herpes zoster viruses, cytomegalovirus, rubella virus and respiratory syncytial virus. When using Z-HL16C cell to isolate virus from 29 adenovirus swab samples collected from 29 soldiers with epidemic high fever in a new military, adenovirus type 3,7 coxsackie virus types B1, B5, B5, B5, B5 were isolated.

CONCLUSIONS

The cell line HL16C has been stably established, it has a broad spectrum in sensitivity for viruses.

Generation of the enol of methyl mandelate by flash photolysis of methyl phenyldiazoacetate in aqueous solution and study of rates of ketonization of this enol in that medium

Flash photolysis of methyl phenyldiazoacetate in aqueous solution produced phenylcarbomethoxycarbene, whose hydration generated a short-lived transient species that was identified as the enol isomer of methyl mandelate. This assignment is supported by the shape of the rate profile for decay of the enol transient, through ketonization to its carbonyl isomer, as well as by solvent isotope effects and the form of acid-base catalysis of the ketonization reaction. Comparison of the present results with previously published information on the enol of mandelic acid shows some interesting and readily understandable similarities and differences.

Selective A(3) adenosine receptor antagonists: water-soluble 3, 5-diacyl-1,2,4-trialkylpyridinium salts and their oxidative generation from dihydropyridine precursors

A(3) adenosine receptor antagonists are sought for their potential antiinflammatory, antiasthmatic, and antiischemic properties. We have found that 3,5-diacyl-1,2,4-trialkyl-6-phenylpyridinium derivatives constitute a novel class of selective A(3) adenosine receptor antagonists. The structure-activity relationships of this class of antagonists, incorporating the 3-thioester, have been explored. The most potent analogue in this group was 2, 4-diethyl-1-methyl-3-(ethylsulfanylcarbonyl)-5-ethyloxycarbonyl -6-phe nylpyridinium iodide (11), which had an equilibrium inhibition constant (K(i)) value of 219 nM at human A(3) receptors (binding of [(125)I]AB-MECA (N(6)-(4-amino-3-iodobenzyl)-5'-N-methylcarbamoyladenosine)) expressed in Chinese hamster ovary (CHO) cells and >10 microM at rat brain A(1) and A(2A) receptors and at recombinant human A(2B) receptors. Compound 11 could be generated through oxidation of the corresponding 3,5-diacyl-1,2,4-trialkyl-6-phenyl-1,4-dihydropyridine, 24, with iodine or in the presence of rat brain homogenates. A 6-cyclopentyl analogue was shown to increase affinity at human A(3) receptors upon oxidation from the 1-methyl-1,4-dihydropyridine analogue, 25, to the corresponding pyridinium derivative, 23 (K(i) 695 nM), suggesting a prodrug scheme. Homologation of the N-methylpyridinium derivatives to N-ethyl and N-propyl at the 1-position caused a progressive reduction in the affinity at A(3) receptors. Modifications of the alkyl groups at the 2-, 3-, 4-, and 5-positions failed to improve potency in binding at A(3) receptors. The pyridinium antagonists are not as potent as other recently reported, selective A(3) receptor antagonists; however, they display uniquely high water solubility (43 mM for 11). Compound 11 antagonized the inhibition of adenylate cyclase elicited by IB-MECA in CHO cells expressing the human A(3) adenosine receptor, with a K(B) value of 399 nM, and did not act as an agonist, demonstrating that the pyridinium salts are pure antagonists.

[Effects of yi qi tong mai oral liquid on acute myocardial ischemia in dogs]

The objective of this study was to assess the prophylactic and therapeutic effects of Yi Qi Tong Mai Oral Liquid (YQTMOL) on acute myocardial ischemia. The models of ischemia were made, in which the anterior coronary arteries of anesthetized dogs were ligated. Four groups of dogs were examined and compared. We determined the extent of their myocardial ischemia and infarction by means of epicardial mapping and N-BT staining. The results showed that in the treatment groups, the increase of sigma-ST was inhibited 30-180 minutes after the oral administration of YQTMOL(compared with control group, P < 0.01), and the sigma-ST was decreased (P < 0.05). Furthermore, in the group dosed with YQTMOL (10 g/kg), the ratios of "area of infarction/heart weight" and "area of infarction/ventricle weight" both decreased (compared with control group, P < 0.05). These findings indicated that YQTMOL reduced the area of myocardial ischemia and the degree of myocardial infarction in dogs, so it could be effective for the prevention and treatment of acute myocardial ischemia.

[CT in diagnosis of tuberculosis of liver and spleen]

OBJECTIVE

To analyze CT findings of hepatospleeno-tuberculosis and to explore the characteristics for diagnosis and differential diagnosis of the disease.

METHODS

CT scans were performed in fifteen patients. There were nine men and six women, the age ranging from 18 to 60 years old. All patients were diagnosed clinically, one of which was confirmed by pathology after surgery, two of which were confirmed by pathology through CT-guided biopsy.

RESULTS

All cases were concurrent with two or more other tuberculosis. Disseminated milliary, small nodules and small saccular foci were present in livers of 8 cases and spleens of 5, and isolated low dense lesion in liver of 1 case, diffuse calcifications in liver and spleen of another 1.

CONCLUSIONS

When disseminated milliary, small nodules and small saccular foci are found by CT in liver or spleen and tuberculous lesions are present in other tissues, diagnosis of liver and/or spleen tuberculosis should be considered.

[CT images in differentiating tuberculous nodules from lung cancers with diameters less than 2 cm]

OBJECTIVE

To find out the CT characteristics of tuberculous nodules and lung cancers with diameters less than 2 cm, and to evaluate their value in differentiating the two diseases.

METHOD

The CT images in thirty patients with tuberculous nodules and forty lung cancer patients with lesions less than 2 cm in diameter were compared.

RESULTS

Smooth or clear edge, non-lobulation, small cavity, calcification, pleural thicking and adhesion, satellitic nidus and perifocal inflammation were found predominant in tuberculous nodules with short-term dynamic changes in shapes, while shaggy border, shallow lobulation, vacuolus sign, air-bronchogram and typical pleural indentation were predominant in lung cancers without dynamic changes in shapes.

CONCLUSION

Thin-slice CT scanning can provide useful images, which by short-term observations are important for differentiating these diseases.

Blood-brain barrier equilibration of codeine in rats studied with microdialysis

PURPOSE

The purpose of the study was to investigate the distribution of codeine across the blood-brain barrier (BBB) in rats by microdialysis (MD).

METHODS

Rats were administered intravenous infusion of codeine in doses of (1) 10 mg/kg, (2) 20 mg/kg for 10 min, and (3) an exponential infusion for 2 h aiming at a plasma concentration of 2500 ng/ml, in a crossover design (n = 6). Microdialysis was used to determine codeine unbound concentrations in blood and brain extracellular fluid (ECF). Total brain tissue and plasma concentrations were also determined. Nalorphine was used as a calibrator for measurement of in vivo recovery.

RESULTS

Relative recovery and retrodialysis loss of codeine and nalorphine were similar both in vitro and in vivo. Codeine was rapidly transported into the brain ECF with identical influx and efflux clearance across the BBB. The AUC ratios of brain to blood were 0.99 +/- 0.25 and 0.95 +/- 0.16 for Dose 1 and 2, respectively. The Css ratio of brain to blood was 1.06 +/- 0.12 for the exponential infusion. The half-lives were 25 +/- 4 min, 22 +/- 2 min in blood and 27 +/- 5 min, 25 +/- 5 min in brain for Dose 1 and Dose 2, respectively. Total brain tissue concentrations were 3.6 +/- 1.2-fold higher than the unbound concentrations in brain. Codeine was demethylated to morphine with an unbound AUCblood,morphine/AUCblood,codeine ratio of 7.7 +/- 5.1% in blood. No morphine was detected in brain MD, but total concentrations were possible to measure.

CONCLUSIONS

Codeine rapidly reached a distributional equilibrium with equal unbound concentrations in blood and brain. The brain transport of codeine did not show any dose-dependency.