Biomedical subjects

T Iga

Publications and source records attributed to T Iga.

At least 145 records · Page 8Linked to original sources

PubMed1992

Pharmacokinetic profile of glycyrrhizin in healthy volunteers by a new high-performance liquid chromatographic method.

An improved high-performance liquid chromatographic method was developed for the quantification of glycyrrhizin and its metabolites in human plasma. The improved method was selective and made it possible to determine precisely glycyrrhizin at levels as low as 500 ng/mL. The pharmacokinetic behavior of glycyrrhizin and its metabolites after oral and intravenous administration of glycyrrhizin to normal subjects was investigated. After oral administration of glycyrrhizin (100 mg) to three normal subjects, the major metabolite of glycyrrhizin (glycyrrhetic acid) appeared in plasma (less than 200 ng/mL), but glycyrrhizin was not found. On the other hand, glycyrrhizin was found in urine, and the amount excreted was 1.1-2.5% of the dose. This finding suggests that glycyrrhizin is partly absorbed in the intact form from the gastrointestinal tract. The concentration of glycyrrhizin in plasma after intravenous administration of glycyrrhizin (40, 80, and 120 mg) showed biexponential profiles during the 24-h period after administration of each dose. The glycyrrhizin metabolites, glycyrrhetic acid and glycyrrhetic acid-3-O-glucuronide, were not detected in either plasma or urine. The terminal half-life of glycyrrhizin, the apparent volume of the central compartment, the steady-state distribution volume, and the total body clearance in three dosing experiments were 2.7-4.8 h, 37-64 mL/kg, 59-98 mL/kg, and 16-25 mL/kg/h, respectively. Glycyrrhizin was not detected in plasma after oral administration of the usual therapeutic dose of glycyrrhizin, and no dose dependency of the drug was observed in the dose range of 40-120 mg.

Administration, Oral↗

PubMed1992

Uptake of organic anions by isolated rat hepatocytes. A classification in terms of ATP-dependency.

Uptake of organic anions into isolated rat hepatocytes was studied to examine their ATP dependency. In the presence of rotenone (0.2 microM), the initial velocity of the uptake (Vo) of dibromosulfophthalein (DBSP; 10 microM), 1-anilino-8-naphthalenesulfonate (ANS; 10 microM) and benzylpenicillin (PCG; 0.02 microM) was reduced to 60-70% of the control value, while that of bromosulfophthalein (BSP; 10 microM), rose bengal (RB; 10 microM) and bromophenol blue (BPB; 10 microM) was not affected. Furthermore, we examined the inhibitory effect of rotenone on the uptake at equilibrium of non-metabolizable ligands (DBSP, BPB and RB). The uptake of these ligands reached equilibrium at 30 min with a cel-to-medium concentration ratio (C/M ratio) of 75, 37 and 126, respectively. The C/M ratio at equilibrium of DBSP was reduced by rotenone to approx. 60% of the control value, while that of BPB and RB was not reduced. Other metabolic inhibitors such as sodium azide (10 mM) and carbonylcyanide-p-trifluoromethoxyphenylhydrazone (FCCP; 10 microM) also reduced the Vo of DBSP and PCG, while the uptake of BSP and RB was not reduced by these inhibitors. These results indicate that organic anions can be classified into two groups according to whether they are taken up by hepatocytes in an ATP-dependent manner, i.e., via active transport or in an ATP-independent manner, i.e., via facilitated diffusion. DBSP, PCG and ANS belong to the former group, whereas BSP, BPB and RB belong to the latter.

Adenosine Triphosphate↗

PubMed1992

Utilization of ATP-depleted cells in the analysis of taurocholate uptake by isolated rat hepatocytes.

The usefulness of ATP-depleted rat hepatocytes in transport studies was examined. ATP-depleted hepatocytes were prepared by incubating cell suspensions with 30 microM rotenone. In ATP-depleted hepatocytes, plasma membrane permeability was increased and mitochondrial membrane potential decreased, while both intracellular volume and pH remained normal. Furthermore, in the presence of valinomycin, the initial uptake rates of 3H-tetraphenyl phosphonium (TPP+) with varied medium concentrations of potassium were predicted according to the Goldman-Hodgkin-Katz equation, which demonstrated that a potassium diffusion potential could be produced in this system. Using the thus-characterized ATP-depleted cells, the uptake mechanism of taurocholate was investigated. In the presence of an inwardly directed Na gradient, the taurocholate uptake was markedly stimulated and bile acid was transiently accumulated at a concentration 3-times higher than at equilibrium ('overshoot') in ATP-depleted cells. No overshoot was observed in viable cells, however, which suggests that in ATP-depleted cells the Na gradient, a driving force for taurocholate uptake, decreased with time. In both viable and ATP-depleted cells, the relationship between medium concentrations of Na and the Na-dependent initial uptake rate were sigmoidal, and the Hill coefficients were close to 2. The Na-dependent initial uptake rate of taurocholate was stimulated by a valinomycin-induced inside negative potassium-diffusion potential in ATP-depleted cells, and the movement of a 'one plus' (as a net) charge was revealed by fitting the data to the Goldman-Hodgkin-Katz equation. These results support the hypothesis that sodium-coupled hepatic uptake of taurocholate occuthrough an electrogenic process with the stoichiometry of 2 Na: 1 taurocholate, although this issue is controversial. In the presence of an outwardly directed sodium gradient, efflux of taurocholate from ATP-depleted cells was not stimulated. Consequently, the physiological transport vector of taurocholate from blood to cell is not only due to the direction of the sodium gradient (blood to cell) but also to membraneous orientation of transport carriers. In conclusion, kinetic analysis using ATP-depleted hepatocytes allowed the formulation of a new approach to clarify the as yet unresolved issues concerning transport stoichiometry and the mechanism for vectorial transport of taurocholate.

Adenosine Triphosphate↗

PubMed1992

Adrenergic mechanisms associated with the movement of platelets in iridophores from the freshwater goby, Odontobutis obscura.

1. Cultured iridophores from the freshwater goby, Odontobutis obscura, were used to investigate adrenergic mechanisms of movement of platelets in the iridophores. 2. Norepinephrine, which was assumed to be the transmitter of the iridophore nerves, induced dispersion of platelets within the cells. 3. The effect of norepinephrine was inhibited by an alpha-adrenergic antagonist, yohimbine, but not by a beta-adrenergic antagonist, propranolol. 4. Isoproterenol, a beta-adrenergic agonist, failed to bring about aggregation of platelets. 5. Forskolin, an activator of adenylate cyclase, was effective in inducing aggregation of platelets. 6. 8-Br-cAMP caused the aggregation of platelets and inhibited the norepinephrine-induced dispersion of platelets. 7. It appears that the adrenoceptors of the iridophores of this species are solely of the alpha type; they mediate the dispersion of platelets; and an increase in intracellular levels of cAMP induces the aggregation of platelets.

Adrenergic alpha-Antagonists↗

PubMed1992

'Albumin-mediated transport phenomenon' observed for ligands with high membrane permeability. Effect of the unstirred water layer in the Disse's space of rat liver.

In this paper, we offer experimental evidence of the rate-limiting diffusion of ligands through the unstirred water layer (UWL) as an explanation for the so-called albumin-mediated transport phenomenon. The relative membrane permeability of various ligands was first evaluated using isolated rat hepatocytes. Then, the effect of albumin on the uptake of ligands of a wide range of membrane permeabilities was examined using the perfused rat liver. The results were similar to those expected from the UWL model: ligands with high membrane permeability (warfarin, diazepam and taurocholate) clearly exhibited albumin-mediated transport, those with medium membrane permeability (tolbutamide and salicylate) showed less albumin-mediated transport, and ligand with low membrane permeability (cefodizime) did not show albumin-mediated transport. These results were explained by simulation studies of two separate cases based on the UWL model; one assuming the rapid equilibrium of ligand binding with albumin, and the other considering the slow dissociation of ligands from albumin. In light of these findings, we suggest that the rate-limiting diffusion through the UWL plays an important role in the so-called albumin-mediated transport phenomenon.

Animals↗

PubMed1992

Kinetic analysis of hepatobiliary transport of vincristine in perfused rat liver. Possible roles of P-glycoprotein in biliary excretion of vincristine.

Recent studies using bile canalicular membrane vesicles have suggested that P-glycoprotein may play a role in excreting some anticancer drugs from the liver to the bile. At steady state after a continuous single-pass perfusion of a tracer concentration of [3H]vincristine in the rat liver, the extraction ratio was approximately 0.6, and 70% of the extracted drug was excreted into the bile mostly in unchanged form. The liver/perfusate and bile/liver unbound concentration ratios obtained after correction for intracellular binding and the inside-negative membrane potentials and/or pH difference between the inside and outside of the cells, were approximately 2-3 and 160-280, respectively, suggesting a highly concentrated biliary excretion process. We also examined the effects of verapamil, a P-glycoprotein-related transport inhibitor in cancer cells, on the hepatobiliary transport of [3H]vincristine. Verapamil 50 microM in the perfusate caused a decrease in the biliary excretion rate of [3H]vincristine, whereas [14C]taurocholate (reference compound) remained constant. In contrast, the hepatic uptake rate of [3H]vincristine exhibited minimum reduction, suggesting that verapamil selectively inhibited the biliary excretion of [3H]vincristine at the canalicular membrane. The fact that verapamil had little effect on the initial velocity of [3H]vincristine uptake by isolated hepatocytes also supports the above findings. Since the effect of 150 microM verapamil in the perfusate was not selective for vincristine, the biliary excretion rates of both compounds ([3H]vincristine, [14C]taurocholate) were reduced by this concentration of verapamil. In conclusion, the concentrative excretion of vincristine into the bile and its selective inhibition by a moderate concentration of verapamil provide indirect evidence for the contribution of P-glycoprotein to the biliary excretion of vincristine in a perfused rat liver system.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1992

Kinetic modeling of ouabain tissue distribution based on slow and saturable binding to Na,K-ATPase.

The significance of the binding to Na,K-ATPase in the tissue distribution of ouabain was previously documented (Harashima et al., Pharm. Res. 9:474-479, 1992). The purpose of this study was to obtain a kinetic model of ouabain tissue distribution. In most tissues, the ouabain concentration continued to rise after the termination of infusion (5 min), with the peak tissue concentration at approximately 20 min. This delay could not be explained by the rapid equilibrium model (RE model), nor could the kinetics of ouabain be explained by an RE model modified for saturable binding. Since ouabain binding to Na,K-ATPase is slow, the association and dissociation processes were incorporated into a model that can accurately fit the observed time courses of ouabain. The obtained binding parameters corresponded well with the observed values in the in vitro binding experiments, except for muscle. These results quantitatively support the role of the slow and saturable binding of ouabain to Na,K-ATPase in its tissue distribution.

Animals↗

PubMed1992

Significance of binding to Na,K-ATPase in the tissue distribution of ouabain in guinea pigs.

Ouabain binds specifically to Na,K-ATPase on the plasma membrane and therefore serves to measure the tissue concentration of Na,K-ATPase. We examined the role of ouabain binding to Na,K-ATPase in its overall tissue distribution. The tissue-to-plasma concentration ratio (Kp,vivo) was defined in each tissue after intravenous administration of 3H-ouabain in guinea pigs, and specific binding of ouabain to Na,K-ATPase was measured in tissue homogenate to obtain the dissociation constant and binding capacity in each tissue. A predicted tissue-to-plasma concentration ratio (Kp,vitro) was calculated using the obtained binding parameters and the volume of extracellular space in each tissue. The absolute values of Kp,vitro were comparable to those of Kp,vivo, except in brain. Regression analysis showed that the specific binding capacity of Na,K-ATPase in each tissue is the main factor in the tissue variation of Kp,vivo. Therefore, the binding of ouabain to Na,K-ATPase plays a significant role in the tissue distribution of ouabain.

Algorithms↗

PubMed1992

Correlation between the inhibitory effects of basic drugs on the uptake of cardiac glycosides and taurocholate by isolated rat hepatocytes.

The role of the multispecific bile acid transporter for cardiac glycoside uptake is still controversial. This study was designed to examine the inhibitory effects of basic drugs (verapamil, dipyridamole, nifedipine, chlorpromazine, disopyramide, quinidine, propranolol, and lidocaine) on taurocholate uptake by isolated rat hepatocytes and to compare these effects with inhibition of ouabain uptake. Sodium-dependent taurocholate uptake was significantly reduced, to 50-70% of the control value, by 50 microM verapamil, dipyridamole, and nifedipine. Sodium-independent taurocholate uptake was more extensively inhibited, to 20-40%, by these basic drugs. The inhibition of ouabain uptake correlated better with sodium-independent taurocholate uptake (gamma = 0.918) than with sodium-dependent taurocholate uptake (gamma = 0.714). Taurocholate competitively inhibited ouabain uptake in the absence of sodium. These results indicate that the cardiac glycoside transport system is similar to the sodium-independent taurocholate transport system.

Animals↗

PubMed1992

Effect of benzylpenicillin on the disposition of cefodizime in rats: no net effect on total clearance due to decreased hepatobiliary clearance and increased renal clearance.

Effect of benzylpenicillin (PCG) on the disposition of [14C]cefodizime (CDZM), a nonmetabolizable analog of cefotaxime, was studied in rats. Rats were divided into two groups to receive i.v. injection of [14C]CDZM (15 mg/kg) alone and during the infusion of PCG. Although the total concentration of [14C]CDZM in plasma vs. time data were almost the same between the groups, the unbound concentration of [14C]CDZM was increased 2-fold by the treatment with PCG. Hepatobiliary excretion of [14C]CDZM was reduced by the treatment with PCG, indicating that PCG inhibits the transport of CDZM across the sinusoidal and/or bile canalicular membrane(s). Further support for this hypothesis is the finding that the uptake of [14C]CDZM by the isolated hepatocytes in vitro was via an active transport process that was reduced by PCG. Furthermore, pharmacokinetic analysis of the data obtained from in vivo and in vitro experiments indicated that PCG reduced the permeability of [14C]CDZM across the sinusoidal and bile canalicular membranes to 32% and 40% of the control value, respectively. The urinary excretion of [14C]CDZM was principally via the glomerular filtration process and was not affected by the treatment with PCG. Because of the 2-fold rise in the unbound fraction of [14C]CDZM in the treated rats, the renal clearance for total [14C]CDZM was increased 2-fold by the treatment with PCG. The increase in the renal clearance compensated for the decrease in the hepatic clearance. The net effect of the alterations in these pharmacokinetic parameters resulted in no change in the time profiles of [14C]CDZM concentration in plasma between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Selective high-performance liquid chromatographic method for the determination of glycyrrhizin and glycyrrhetic acid-3-O-glucuronide in biological fluids: application of ion-pair extraction and fluorescence labelling agent.

A selective high-performance liquid chromatographic method has been developed for the simultaneous determination of glycyrrhizin and glycyrrhetic acid-3-O-glucuronide in biological fluids of the rat. The procedure is based on the ion-pair formation using tetra-n-amylammonium bromide, extraction with ethyl acetate-n-heptane from the salt-saturated aqueous phase, labelling with 4-bromomethyl-7-methoxycoumarin, followed by chromatographic separation with fluorescence detection. Glycyrrhizin in plasma, bile and urine could be precisely determined in concentrations as low as 1, 1 and 2.5 micrograms/ml, respectively, in a 0.1-ml sample. The equivalent values for the glucuronide were 1, 2.5 and 2.5 micrograms/ml, respectively. The method is applicable in pharmacokinetic studies of glycyrrhizin in small animals.

Animals↗

PubMed1991

Pharmacokinetics of ambenonium, a reversible cholinesterase inhibitor, in rats.

The pharmacokinetics of ambenonium, a reversible cholinesterase inhibitor, in rats was investigated following intravenous administration of the drug. Mean residence time and steady state volume of distribution were 23-36 min and 0.20-0.311 kg-1, respectively, and were dose independent at the dose of 0.3-3 mumole kg-1. Total body clearance of 8.2 ml min-1 kg-1 over 0.3 mumole kg-1 was slightly increased to 11.3 ml min-1 kg-1 at 3 mumole kg-1. Renal clearance was also increased with the increase of the dose, while hepatobiliary clearance was substantially constant. Ambenonium was highly concentrated in the liver, kidney, spleen, and lung. About 30 per cent of the dose is concentrically stored in the liver at 6 h after administration, and had not disappeared after 24 h.

Ambenonium Chloride↗

PubMed1991

Comparison of the methods for determining cell-surface and intracellular receptors for epidermal growth factor in the rat liver.

We compared methods for determining the distribution of epidermal growth factor (EGF) receptors between the cell surface and the cell interior in the rat liver. Incubation of isolated hepatocytes with 100 nM EGF for 20 min at 37 degrees C remarkably decreased the cell-surface EGF receptor density (internalization of receptors). The detergent Brij 35 was previously reported to permit assay of the intracellular latent EGF receptors in liver homogenates, but in the present investigation, Brij 35 lowered the affinity of EGF for the receptor depending on the detergent concentration, and the appearance of latent receptors was not observed. In contrast, permeabilization of the cells with digitonin, followed by an acid-washing procedure, increased the EGF binding capacity to close to the control level. Hence, the EGF receptors, internalized together with EGF molecules, were not degraded for at least 20 min, and the digitonin method is suitable for quantifying the intracellular EGF receptors. The binding capacities of the digitonin-treated and untreated control cells showed no difference upon digitonin treatment, suggesting that the bulk of EGF receptors exists on the cell surface. Further, cell-surface EGF receptor density was determined after the i.v. administration of EGF (300 micrograms/kg) to rats. Isolated hepatocytes prepared 30 min after the administration of EGF showed little binding for EGF on the cell surface, while the cell-surface EGF receptor density recovered to close to control values in cells prepared after 3 hr.

Animals↗

PubMed1991

Kinetic analysis of receptor-mediated endocytosis of epidermal growth factor by isolated rat hepatocytes.

The interaction of epidermal growth factor (EGF) with cell surface receptors and their subsequent endocytosis in isolated rat hepatocytes were analyzed by measuring changes in the concentrations of cell surface-bound, internalized, and degraded EGF. The kinetic model proposed by Wiley and Cunningham (Cell 25: 433-440, 1981) and Gex-Fabry and Delisi [Am. J. Physiol. 247 (Regulatory Integrative Comp. Physiol. 16): R768-R779, 1984] was basically utilized for the model analysis. The following kinetic parameters were obtained: association and dissociation rate constants for EGF-receptor interaction, internalization rate constant for EGF-receptor complex (kappa e), internalization rate constant for free receptor (kappa t), sequestration rate constant (kappa s) of the complex from shallow (exchangeable) to deep (nonexchangeable) membraneous compartment, intracellular degradation rate constant and initial cell-surface receptor density. The kappa s value, which was obtained by analyzing the time profiles of EGF association with cells, was approximately 5-10 times larger than the kappa e value determined by directly measuring internalized EGF with the acid-washing technique. This suggests the necessary presence of deep (nonexchanging) compartment of the complex in the plasma membrane. The calculated kappa e value is at least several times larger than the kappa t value, yielding the kinetic basis for the occurrence of receptor downregulation induced by excess EGF. We conclude that, in the overall receptor-mediated processing of EGF after bound to the cell surface receptors, the dissociation process is rapid [half-time (t1/2) less than 1 min], the degradation process is much slower (t1/2 approximately equal to 3 h), and the receptor internalization process is intermediate (t1/2 approximately equal to 6-7 min). In addition, two pools for EGF-receptor complex in the plasma membrane seem to be present, although their identification cannot be made.

Animals↗

PubMed1991

Kinetic analysis of clearance of epidermal growth factor in isolated perfused rat kidney.

Our previous in vivo studies identified the saturable uptake of epidermal growth factor (EGF) by rat kidney (D.C. Kim, Y. Sugiyama, H. Sato, T. Fuwa, T. Iga, and M. Hanano, J. Pharm. Sci. 77: 200-207, 1988). In the present study, renal handling of EGF in filtering and nonfiltering isolated perfused rat kidneys was investigated. At designated times after the recirculatory perfusion of 125I-EGF in the nonfiltering kidney, the surface-bound and internalized EGF were separately determined by an acid-washing technique. Time profiles of cell-surface-bound and internalized EGF obtained at the perfusion of a tracer 125I-EGF were fitted to the pharmacokinetic model, and kinetic parameters obtained were as follows: konRs = 0.49 ml.min-1.g-1, koff = 0.87 min-1, kint = 0.20 min-1 where konRs is the binding clearance of EGF with its receptor and koff and kint represent the dissociation and internalization rate constants of the EGF-receptor complex, respectively. The Scatchard analysis of the concentration-dependent EGF binding in the nonfiltering kidney suggests the presence of two binding components, one with high affinity [the apparent dissociation constant (Kd1 = 0.1 nM) and the other with low affinity (Kd2 = 30 nM]. By comparing the internalization clearance (CLi) with filtering and nonfiltering kidneys, we concluded that the renal uptake of EGF occurs mainly from the antiluminal side via receptor-mediated endocytosis in a saturable manner and that the nonsaturable reabsorption of EGF from the luminal membrane after glomerular filtration is relatively small. The contribution of reabsorption, however, becomes larger with the increase in EGF concentration.

Absorption↗

PubMed1991

Kinetic evaluation for measurement of in vivo receptor occupancy by psychotropic drug in brain: implication for human studies.

In vivo receptor occupancy of psychotropic drugs in brain can be estimated by measuring the tissue radioactivity of the tracer, which binds specifically to the receptor unoccupied by the drugs (back titration method). In this study, the validity of this method was evaluated by computer simulation, using various values for the plasma elimination rate, rate of transport across the blood-brain barrier, rate of receptor association and dissociation for both drug and tracer, and the sampling time. The differential equations based on a nonlinear three-compartment model including a plasma pool, precursor pool, and specific binding pool were solved numerically by the Runge-Kutta-Gill method. The receptor occupancy calculated by this method was close to the true value when the plasma concentration and specific binding fraction of the drug did not change greatly during circulation of the tracer. Although the error in calculated occupancy at 5 min after the tracer administration was smaller than that at 20 min, tracer may not greatly accumulate in brain tissue during the initial 5 min in some situations. Our analysis shows that it is necessary to adequately control the elimination rate of drug from plasma and to allow sufficient time for radioactivity to accumulate in the tissue. Therefore, this method requires previous knowledge of the pharmacokinetic behavior of both the drug and the tracer in plasma and tissue. The operation scheme that we suggest for the accurate measurement of the receptor occupancy in vivo can be used in human studies with positron emission tomography and may be useful for therapeutic drug monitoring.

Brain↗

PubMed1991

Kinetic evaluation of pharmacological effects based on allosteric coupling of the benzodiazepine/gamma-aminobutyric acidA receptor in the brain.

A mathematical allosteric coupling model has been proposed to describe the process by which binding to the benzodiazepine/gamma-aminobutyric acid (GABA) receptor complex initiates a biological response. The model states that the first receptors (benzodiazepine receptors) can diffuse independently in the plane of the membrane and reversibly associate with the second receptors (GABA receptors) to regulate their activity (induction of increased chloride ion flux due to the opening of the chloride ion channel). The ratio of agonist-bound to total GABA receptor density was defined to be directly proportional to the biological response in the model. The analysis makes the following assumptions: i) the binding affinity of agonists (muscimol or benzodiazepine) to the benzodiazepine receptor/GABA receptor complex is much greater than that to each receptor alone; ii) the double receptor-single agonist (benzodiazepine, muscimol or GABA) ternary complex binds to the other agonist with a high binding affinity as compared with that of each agonist to an agonist-free receptor complex; iii) benzodiazepine receptor-GABA receptor interaction is enhanced in the presence of each agonist; iv) the GABA receptor is desensitized after the binding of GABA agonist (GABA or muscimol) to the receptor. The modeling exercise shows that the benzodiazepine concentration required for half-maximal biological response is lower than that required for half-maximal receptor binding. In the case of the GABA agonist, a linear relationship between receptor occupancy and biological response was observed. The degree of discrepancy between the two profiles (receptor occupancy and biological response) concerning benzodiazepine concentration dependency and time dependency increased with a decrease in the dissociation constants based on the benzodiazepine receptor-GABA receptor interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain↗

PubMed1991

[Development and evaluation of the comment aid system for therapeutic drug monitoring. I. Application to valproate].

A comment aid system for therapeutic drug monitoring (TDM), which produces the primary comment on the dosage regimen of valproate, was developed. This system produces consulting comments with a fuzzy theory, by using the dosage regimen of valproate, pharmacokinetic parameters estimated by the Bayesian method, and therapeutic effect and toxicity of anticonvulsants evaluated by the physician. For nearly 90% in 42 cases, comments of the system were agreeable comparing with the notes of TDM technologists. There are a few disagreements between this system and experts, mainly because the system does not use enough information about combination therapy with other anticonvulsants. Developed comment aid system shows some clinical and educational utility, and suggests significance and possibility of more useful and al around TDM expert system. Then this system might be available as a prototype of the TDM expert system.

Adolescent↗