Interaction between valproic acid and carbamazepine: an in vitro study of protein binding

Valproic acid (VPA) is highly bound to plasma protein (92-96%) and is likely to compete with carbamazepine (CBZ), another drug that is bound extensively (75%). CBZ protein binding was evaluated in vitro by ultrafiltration at concentrations within the therapeutic range (6, 8, and 12 micrograms/ml), while also varying VPA concentrations (0, 50, and 100 micrograms/ml). Using ultrafiltration, we found a significant elevation (p less than 0.01) in free and percent-free CBZ for every CBZ concentration tested as the total VPA concentration increased. Maximal effect was evident at 12 micrograms/ml CBZ. The free fraction increased from 23.5% free CBZ controls (2.85% micrograms/ml free) to 29.5% free CBZ (3.56% micrograms/ml free), with 100 micrograms/ml VPA a 25% increase in free CBZ. This in vitro study demonstrates that VPA competes with CBZ for plasma protein binding sites, resulting in a significant increase in free CBZ that may be clinically important.     

Irreversible inhibition of human cytomegalovirus replication by topoisomerase II inhibitor, etoposide: a new strategy for the treatment of human cytomegalovirus infection.

We demonstrated previously that human cytomegalovirus (CMV) infections could enhance the expression of cellular topoisomerase II and this enzyme activity is essential for CMV to replicate in vitro (Benson and Huang, 1988; Benson and Huang, 1990). In this study, we further show that in addition to m-AMSA and VM26 which we had previously reported, a widely used and clinically available drug, etoposide (VP-16 or VePesid) can irreversibly inhibit CMV replication at the drug concentration (2.5 micrograms/ml) greatly below toxic levels to stationary phase cells. Growing cells were more sensitive to etoposide than stationary phase cells and slight growth inhibition occurred at 2.5 micrograms/ml level. This inhibitor does not prevent the expression of CMV immediate-early and early genes, but can inhibit viral DNA and late viral-proteins synthesis. Because of their irreversible inhibitory effects and approval usage in clinical oncology, it is suggested that this group of compounds, particularly etoposide (VP-16), can be used to control life-threatening CMV infections, such as CMV pneumonitis and CMV retinitis, in cancer and immunocompromised patients or patients with AIDS.     

一些保肝药物对原代培养大鼠肝细胞糖原合成功能的影响

本文参照PO Seglen的方法并加以修改,建立了原代培养大鼠肝细胞糖原合成功能的测定体系。观察到联苯双酯既能使正常肝细胞合成糖原增加88%,又能保护肝细胞完全拮抗四氯化碳对其功能的损伤;银耳多糖能使四氯化碳对肝细胞糖原合成功能的损伤减轻57%;去甲斑蝥素10μg/ml能增加肝细胞糖原合成,浓度增加到100μg/ml时,此作用减弱,1000μg/ml则明显抑制糖原的合成,而且在10～100μg/ml浓度时,即能加强四氯化碳的损伤作用;100μg/ml CL₁₅₀₀和熊果酸二钠单独应用可增加肝细胞糖原合成,但与四氯化碳同时应用,反而加重对糖原合成的抑制作用。     

Displacement of lidocaine from serumα 1-acid glycoprotein binding sites by basic drugs

Since little is known of the number and types of binding sites on alpha 1-acid glycoprotein (AAG) and because drug-drug protein binding interactions often fail to fit a simple model, a study of the effect of 9 known AAG binding drugs on lidocaine free fraction (LFF) was performed. Serum was obtained from 10 healthy males, pooled and various concentrations (from 0.15 to 1000 micrograms/ml) of amitriptyline, bupivacaine, chlorpromazine, disopyramide, imipramine, meperidine, nortriptyline, propranolol and quinidine were added. LFF was determined by equilibrium dialysis at an initial lidocaine concentration of 2.0 micrograms/ml. LFF increased from 0.30 +/- 0.019 (mean +/- SD) in the absence of displacing agents to maximum values ranging from 0.59 (nortriptyline) to 0.73 (bupivacaine). Plots of LFF vs. the logarithm of displacing drug concentration yielded simple sigmoidal curves in all cases. LFF was increased 50% by an initial bupivacaine concentration of 6.0 micrograms/ml with all other drugs requiring more than 10 micrograms/ml to increase LFF to that extent. Lidocaine binding in a 4.5 g/dl albumin solution was unaffected by concentrations of quinidine, meperidine, nortriptyline and bupivacaine up to 200 micrograms/ml. Addition of AAG to serum reduced LFF as expected. A plot of the reciprocal of bound drug concentration vs. the reciprocal of free drug concentration in the presence and absence of quinidine suggested a competitive binding interaction. These data indicate that the binding interactions between lidocaine and the various displacing compounds are not significantly complicated by cooperative effects and that, with the possible exception of bupivacaine, displacement of lidocaine by any of these drugs is likely to be of clinical significance.     

Cytotoxic effects of amiodarone and desethylamiodarone on human thyrocytes

Since recent in vivo evidence suggests that the benzofuran antiarrhythmic drug amiodarone has a direct toxic effect on the human thyroid gland, we have investigated the effects of both amiodarone and its metabolite desethylamiodarone on a novel immortalized functional human thyrocyte line (SGHTL-34 cells). Desethylamiodarone markedly reduced cell number as assessed from both DNA and protein content. Few cells were left after 24 hr exposure to 12.5 micrograms/ml; the concentration producing death of 50% of cells (EC50) was 6.8 +/- 1.1 micrograms/ml (mean +/- SE, N = 15). Amiodarone was much less potent, producing a maximum decrease in cell number of approximately 25% at concentrations up to 50 micrograms/ml. The effect of desethylamiodarone was seen within 24 hr of culture. T3 in concentrations up to 0.75 micrograms/ml had no effect on the action of amiodarone or desethylamiodarone on SGHTL-34 cells. Light microscopy demonstrated vacuolation of SGHTL-34 cells after 4-day culture with either the drug or its metabolite. Studies using primary cultures of human retroorbital fibroblasts demonstrated that the greater cytotoxicity of desethylamiodarone was not confined to thyrocytes. When SGHTL-34 cells were incubated with 2.5 micrograms/ml desethylamiodarone for 4 days, 71.7 +/- 0.9% was taken up by the cells; there was no detectable conversion to amiodarone. Incubation of thyrocytes with 50 micrograms/ml amiodarone for 4 days resulted in the uptake of 80.1 +/- 2.1% by the cells. In addition, 5.0 +/- 0.1% of the amiodarone was converted to material with the same retention time as desethylamiodarone standard; of this material, 72.9 +/- 2.8% was taken up by the cells. We conclude that desethylamiodarone, at concentrations near those found in the plasma of patients on long-term amiodarone therapy, exerts a direct cytotoxic effect on human thyroid cells in short-term culture. This effect may play a role in the aetiology of clinical thyroid disease during amiodarone therapy. We suggest that, since the effect is not restricted to thyrocytes, desethylamiodarone may play a role in the aetiology of amiodarone toxicity which occurs clinically in many tissues.     

Pharmacokinetic studies of astromicin using a constant-rate continuous intravenous infusion method

Astromicin (ASTM) was administered intravenously to 4 healthy adult volunteers with an average body weight of 62 kg using a continuous infusion apparatus at a constant rate of 200 mg in 1 hour (Group I), 400 mg in 1 hour (Group II) and 200 mg in 2 hours (Group III). Concentrations of the drug in serum and urine were determined by high power liquid chromatography (HPLC). The mean serum concentration of the 4 subjects reached the peak of 13.32 micrograms/ml in Group I, 22.12 micrograms/ml in Group II and 9.89 micrograms/ml in Group III. The peak concentration was achieved at the end of infusion and was dose-related. After 8 hours, the concentration dropped to less than 1 micrograms/ml in all groups. The urinary recovery rate was 90% in 8 hours and 95% in 24 hours. T1/2 (beta) analyzed by the two-compartment open model was 1.64-1.72 hours. AUC infinity was also dose-related, such as 33.1 micrograms X hr/ml and 31.6 micrograms X hr/ml in Group I and Group III, and 57.6 micrograms X hr/ml in Group II. It is recommended for amikacin (AMK) that the peak serum concentration should not exceed 35 micrograms/ml and the maximum concentration before the next infusion should be less than 5 micrograms/ml. In these experiment, ASTM which is lower in toxicity than AMK did not approach 35 micrograms/ml even at the peak level with the dosage of 400 mg in 1 hour. Furthermore, the excretion of the drug was fast and the serum level of the drug became much lower than 5 micrograms/ml very quickly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Dual effects of carbamazepine-phenytoin interaction

By intrapatient comparison at constant phenytoin (PHT) dose, the effect of increased carbamazepine (CBZ) dose was studied in 32 epileptic outpatients treated with a combination of PHT and CBZ. The mean PHT plasma concentration, as well as the concentration/dose ratio for PHT, became significantly higher secondary to increased doses of CBZ (14.1 +/- 3.5 vs. 19.3 +/- 3.6 micrograms/ml and 2.8 +/- 1.0 vs. 3.9 +/- 1.4 micrograms/ml plasma per milligram/kilogram daily dose, respectively; p less than 0.001). Concomitantly, in spite of CBZ dose higher by 17.6%, the CBZ concentration increased by only 6.4%, and the CBZ concentration/dose ratio actually decreased by 10%. In contrast, by intrapatient comparison at constant CBZ dose, the effect of reduced PHT dose on CBZ was studied in 22 patients. The mean CBZ plasma concentration as well as the concentration/dose ratio for CBZ appeared significantly higher, with a concomitant reduction of PHT (6.7 +/- 1.6 vs. 8.6 +/- 1.6 micrograms/ml and 0.37 +/- 0.1 vs. 0.49 +/- 0.2 micrograms/ml plasma per milligram/kilogram daily dose, respectively; p less than 0.001). This simultaneous dual effect--inhibition of PHT metabolism by CBZ and induction of CBZ metabolism by PHT--can result in PHT intoxication along with a fall in CBZ plasma concentration to a subtherapeutic range. This effect may be avoided or reduced if the PHT concentration is adjusted to approximately 13 micrograms/ml before CBZ is added or increased.     

Basic and clinical studies on cefotaxime

The most frequently encountered infectious disease in the field of internal medicine is respiratory tract infections. One of the most important requirements for an antibiotic in the treatment of infections is that it must be efficiently transferred to the infected site to attain a high concentration there. In the case of respiratory tract infections, it is desirable for the drug concentration in the sputum to be higher than the MIC for the causative bacterium. Cefotaxime (CTX) expresses potent antibacterial activity against Haemophilus influenzae, Klebsiella pneumoniae and Streptococcus pneumoniae, which are the major causative bacteria of respiratory tract infections. CTX also exerts antibacterial effects against a wide range of other bacteria. We administered CTX to patients with respiratory tract infections, then measured and compared the drug concentrations in the serum and sputum. The results are described below. When 2 g of CTX was drip-infused, the drug concentration in the serum was 113.0 micrograms/ml at 5 minutes after the completion of infusion, 64.9 micrograms/ml at 30 minutes, 38.7 micrograms/ml at 1 hour, 19.0 micrograms/ml at 2 hours, 8.9 micrograms/ml at 4 hours and 3.8 micrograms/ml at 6 hours. The drug concentration in the sputum was 1.29 micrograms/ml at 5 minutes after completion of infusion, 1.54 micrograms/ml at 5 to 30 minutes, 1.36 micrograms/ml at 30 minutes to 1 hour, 1.47 micrograms/ml at 1 to 2 hours, 1.12 micrograms/ml at 2 to 4 hours and 1.35 micrograms/ml at 4 to 6 hours. The drug concentration in the serum was the highest at 5 minutes after completion of the drip-infusion, and then it gradually decreased.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of furosemide on vascular smooth muscle is influenced by plasma protein

The effect of furosemide on vascular smooth muscle was studied on segments of rabbit blood vessels. Furosemide (20 micrograms/ml) induced small (3-4%) decreases in resting tension whereas nitroglycerin (0.5 micrograms/ml) induced decreases from 8 to 13%. The addition of albumin (45 g/l) abolished the furosemide response whereas the nitroglycerin response was unaffected. Similarly the pronounced effect of nitroglycerin on electrically evoked contractions was unaffected by the presence of albumin whereas the furosemide effect was weakened by albumin. The biologically determined free fraction of furosemide increased with increasing drug concentrations from 13% at 16 micrograms/ml to 35% at 256 micrograms/ml.     

Urinary excretion kinetics of famotidine in rats

Famotidine is a new histamine H2-receptor antagonist which has been demonstrated to be more potent than cimetidine and ranitidine in inhibiting gastric acid secretion. Nine groups of adult male Sprague-Dawley rats received an ia injection of various loading doses of famotidine followed immediately by a constant infusion of the drug at different rates for 6 hr. When steady state famotidine concentrations in plasma were low, renal clearance of the drug (CLR) was greater than glomerular filtration (GFR), and the ratio CLR/GFR was about 4.5 at plasma concentrations of 0.2-1.8 micrograms/ml, suggesting that famotidine was actively secreted by the renal tubules. The CLR decreased as famotidine concentration in plasma increased, and the ratio CLR/GFR approached 1 in the concentration range of 25-76 micrograms/ml, thus providing evidence for saturation of the secretory mechanism. The maximum rate of secretory transport (Tm) of famotidine averaged 180 micrograms/min/kg. On average, some 50-70% of an ia bolus dose was excreted in the urine as unchanged drug within 24 hr of administration. Over the dose range of 0.3-30 mg/kg famotidine, there was no dose-dependent effect on total or renal clearance. Since the lowest dose level, 0.3 mg/kg, is below the recommended human therapeutic dose for famotidine (0.6 mg/kg), the saturation of the renal excretion process observed here in rats is not likely to be of clinical significance.     

Effect of glutaraldehyde on cultured cells--restraining effect on multiplication of L cells

Glutaraldehyde (GA) was tested for its cytotoxic effect on L cell tissue culture system in comparison with formaldehyde (FA). In the first study, the replanted cells were grown to monolayers on the flattened bases of the culture tubes, and then exposed to the drug. In the second study, the drug was added to the cell suspension just put in the culture tubes. In either case, the cells were kept in contact with the drug at 37 degrees C for 24, 48 or 72 hr, after which time the monolayers were removed and the viable cells in each of the tubes were counted up. The change in the number of viable cells was examined in the various concentrations of the drugs and time intervals of cell-drug contact. Both GA and FA showed relatively slight toxic effect when each concentration was 1 microgram/ml. The cells exposed to 1, 10 micrograms/ml of GA or 1 microgram/ml of FA were able to increase in number, though markedly restrained from their multiplication if compared with the control. GA and FA seriously diminished the viable cells at a concentration of 100 micrograms/ml and 10 micrograms/ml, respectively, and they were so toxic that complete cell death was immediately caused even when the concentration of each drug was at 1000 micrograms/ml. Just replanted cells showed less tolerance to the drug effects than the cells of established monolayers; suppression of cell growth was noted with the concentration of 0.8 microgram/ml and above of either GA or FA, and complete cell death was caused by 58 micrograms/ml of GA and 7.0 micrograms/ml of FA.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ex vivo protein binding of clindamycin in sera with normal and elevated alpha 1-acid glycoprotein concentrations.

Clindamycin is a lincosamide antibiotic that binds primarily to alpha 1-acid glycoprotein (AAG), an acute-phase serum protein. Many studies have shown that AAG concentrations increase in response to stress, including infection, myocardial infarction, and trauma. The objectives of this study were to determine the serum protein binding of various clindamycin concentrations in sera with normal and elevated AAG concentrations. Serum was obtained from 4 healthy volunteers and 12 patients with pathophysiologic conditions known to elevate serum AAG concentrations. Timing for collection was determined from the literature, corresponding with the expected peak concentration for each disease state. Samples were assayed for AAG by radial immunodiffusion and were spiked with clindamycin to achieve total concentrations of 10 micrograms/ml (n = 18), 4 micrograms/ml (n = 10), and 2 micrograms/ml (n = 7). Protein binding was determined by ultrafiltration and subsequent high-performance liquid or gas chromatography. Protein binding was dependent on the serum concentrations of both AAG and clindamycin. When AAG concentrations increased from 101-150 mg/dl to 201 mg/dl or greater, mean protein binding increased from 81.2% to 92.4% (p = 0.1265) and from 61.3% to 88.6% (p less than 0.05) at clindamycin concentrations of 2 and 4 micrograms/ml, respectively. With AAG concentrations between 101 and 150 mg/dl, mean protein binding increased from 62.4% at 10 micrograms/ml to 81.2% at 2 micrograms/ml (p = 0.1514). Since AAG concentrations may increase in certain patients, the concentration of free (pharmacologically active) drug may fall below the minimum inhibitory concentration for several pathogens earlier in a dosing interval.     

Valproic acid: in vitro plasma protein binding and interaction with phenytoin.

Because valproic acid (VPA) is highly bound to plasma protein, several variables affecting binding will significantly alter the quantity of free drug which is pharmacologically active. Therefore, total VPA plasma concentrations do not reflect the therapeutic strength of the drug in tissue. We have performed equilibrium dialysis and ultrafiltration studies of VPA binding to plasma protein. The converging data in these in vitro studies indicate a clinically significant alteration in the percent of free VPA when total drug concentration exceeds 80 micrograms/ml. Saturation of drug binding sites probably occurs in this range. At 20--60 micrograms/ml VPA there is 5% free drug, with a significant increase to 8% free at 80 micrograms/ml; free drug increases to over 20% at 145 micrograms/ml total VPA. Human plasma, which is low in albumin, has twice the quantity of free VPA as normal plasma (10 versus 5% free). The clinical evidence of interaction between VPA and phenytoin is confirmed in vitro by the increase in the free fraction of both drugs. VPA binding decreases by 3--6%, while phenytoin binding decreases 5--6% as both drugs reach high plasma concentrations. When appropriate, laboratory reports should be available defining concentration of free drug in plasma for optimal interpretation of drug concetrations relative to clinical effects.     

Cytotoxicity studies on T-3262 in cultured Chinese hamster cells

T-3262 is an antibacterial drug which belongs to the group of pyridonecarboxylic acids. In this study, we investigated cytotoxicity of T-3262 for inhibition of cell growth and effects on viability of, and morphological changes in cultured Chinese hamster cells (V79 cells). The following results were obtained. 1. The 50% inhibition dose of T-3262 for cell growth (ID50, cultured for 48 hours) was 12 micrograms/ml, showing that the inhibitory effect of T-3262 on the cell growth was stronger than that of enoxacin (ENX: ID50 44 micrograms/ml), norfloxacin (NFLX: ID50 105 micrograms/ml) or ofloxacin (OFLX: ID50 145 micrograms/ml). 2. The number of cells increased and dead cells were scarcely seen at the highest concentration tested in culture medium (40 micrograms/ml of T-3262 for 48 hours). At this concentration, degeneration of cytoplasm (atrophy and round shape) and decrease of mitotic cells were observed. These morphological changes were similar to those of the cells treated 400 micrograms/ml of NFLX or OFLX for 48 hours. 3. After the removal of T-3262 from culture medium, the cells began to grow actively and recovered from the morphological changes. The similar phenomenon was observed with ENX treated cells but not with fluorouracil or mitomycin C treated cells.     

Studies on antimicrobial concentration of clindamycin phosphate in serum, pelvic dead space exudate, and pelvic organs/tissues

In women undergoing radical and total abdominal hysterectomy, clindamycin phosphate (CLDM-P) in a dose of 1,200 mg was administered by intravenous drip infusion over 1 hour and the drug concentrations in serum and pelvic dead space exudate, as well as pelvic organs/tissues, were determined over time. The following results were obtained: The serum concentration of clindamycin (CLDM) after intravenous infusion showed the peak value of 24.54 +/- 7.02 micrograms/ml at the end of infusion and then gradually decreased to 3.87 +/- 0.70 micrograms/ml in 6 hours. Concentration in pelvic dead space exudate, which was 2.82 +/- 3.90 micrograms/ml at the end of intravenous infusion, gradually increased to the peak value of 13.49 +/- 6.62 micrograms/ml in 1 hour. Two hours after infusion, the level of 12.43 +/- 5.56 micrograms/ml outstripped serum concentration. Continuously in excess of serum concentration, the exudate concentration gradually decreased to 6.65 +/- 2.27 micrograms/ml at 6 hours after infusion. Cubital venous serum concentration (16.36 +/- 3.68 micrograms/ml) was almost equal to uterine arterial serum concentration (16.36 +/- 4.05 micrograms/ml) of CLDM at uterine removal. In the pelvic organ/tissue concentrations, 15.71 +/- 3.86 micrograms/g in endometrium was highest, followed by 15.19 +/- 3.80 micrograms/g in oviduct, 14.80 +/- 3.52 micrograms/g in myometrium, 14.74 +/- 4.02 micrograms/g in ovary, 14.09 +/- 2.90 micrograms/g in portio vaginalis. The concentration was lowest (11.49 +/- 1.44 micrograms/g) in cervix uteri. Clinically, combined treatment with CLDM-P and ceftizoxime was excellently effective for endometritis induced by P. asaccharolyticus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical study on imipenem/cilastatin sodium in the field of pediatrics

Imipenem/cilastatin sodium (MK-0787/MK-0791) was administered to pediatric patients with infections, and the following results were obtained. Pharmacokinetic study Two children, 11 years of age (38 kg body weight) and 3 years of age (15.5 kg body weight), were administered by 30 minutes intravenous drip infusion a single dose of 500 mg/500 mg (13.2 mg/13.2 mg per kg) and 250 mg/250 mg (16.1 mg/16.1 mg per kg) of MK-0787/MK-0791, respectively. Serum concentrations of MK-0787 reached their peaks at the end of drip infusion at a value of 56.33 micrograms/ml and 55.98 micrograms/ml, respectively. Concentrations of the drug decreased as the time after the administration increased, and they reached 0.14 microgram/ml and 0.12 microgram/ml, respectively in the older and the younger children at 6 hours after the administration. Half-lives (T 1/2) of the drug in serum were calculated to be 1.21 hours and 1.04 hours, respectively. The concentration of the drug in cerebrospinal fluid for the 11 years old was 0.52 microgram/ml 2 hours after the drip infusion and the serum concentration at the time was 4.02 micrograms/ml. Peak serum concentrations of MK-0791 in the 2 children were 53.73 micrograms/ml and 22.99 micrograms/ml, respectively, at the end of drip infusion. After 1 hour, the serum concentration of the drug decreased to 10.54 micrograms/ml in 1 case and not detectable in the other case. Urinary recovery rates of MK-0787 in 6 hours after the drip infusion was 82.9% and 63.6% in the 2 children and those of MK-0791 were 57.9% and 74.6%. Clinical study Clinical studies on MK-0787/MK-0791 were carried out in 6 pediatric patients; 1 each with femoral cellulitis, sepsis suspected, salmonellosis, acute tonsillitis, bronchopneumonia and streptococcosis. Lengths of treatment were 2 2/3-4 days for 5 cases and 6 days for 1 case. The patients were treated by 30-60 minutes intravenous drip infusions twice a day for 1 case, and 3 times a day for 5 cases at daily doses of 54.5-66.7 mg/kg. The treatment was effective in all cases, with 3 cases judged excellent and 3 cases good. The safety of the drug was studied in 7 patients. No side effects nor clinically abnormal values were observed in any cases.     

Activity of dipyrone on intraplatelet arachidonic acid metabolism: an in vitro study

The effects of dipyrone on platelet cyclooxygenase and lipoxygenase were investigated in vitro by the study of 1-14C arachidonic acid (AA) conversion by high performance liquid chromatography (HPLC) on washed platelets at seven different drug concentrations (from 5 to 300 micrograms/ml). The effects of dipyrone on thromboxane (TX) B2 generation from endogenous AA were also studied in platelet-rich plasma and in washed platelets by radioimmunoassay. In the study of 1-14C AA metabolism the inhibitory concentration (IC) 50 for TXB2 was 40 micrograms/ml. However, at the lowest drug concentration (5 micrograms/ml) a slight but significant inhibition was found (25.3%, P less than 0.001) and a complete one at 300 micrograms/ml. A relationship between TXB2 inhibition and log drug concentration was found (r = 0.97, P less than 0.001). Lipoxygenase (LO) activity showed an increase of 45.9% at 20 micrograms/ml and of 251.5% at the highest concentration (r = 0.97, P less than 0.001). The inhibition of TXB2 generation from endogenous AA by washed platelets was of the same order of magnitude of the inhibition of TXB2 production from exogenous 1-14C AA. Our results indicate that dipyrone affects intraplatelet AA metabolism at very low concentrations, however its activity, on a molar ratio basis, appears to be lower than that of other non-steroidal anti-inflammatory drugs.     

Studies on antimicrobial concentrations of flomoxef in serum, pelvic dead space exudate, and pelvic organs/tissues

To women undergoing radical and total hysterectomy, flomoxef (FMOX, 6315-S) in a dose of 2 g was administered by intravenous drip infusion over 1 hour and drug concentrations in serum and pelvic dead space exudate as well as pelvic organs/tissues were determined over time. The following results were obtained: 1. Serum concentrations of FMOX after intravenous infusion showed the peak value of 92.86 +/- 17.05 micrograms/ml at the end of infusion and then gradually decreased to 29.00 +/- 10.49 micrograms/ml in 1 hour and 1.16 +/- 1.08 micrograms/ml in 6 hours. 2. Concentrations in pelvic dead space exudate, which were 6.54 +/- 3.21 micrograms/ml at the end of intravenous infusion, gradually increased to 31.28 +/- 12.69 micrograms/ml in 30 minutes, and the peak of 35.21 +/- 13.29 micrograms/ml in 1 hour. Exudate concentrations gradually decreased to 11.10 +/- 6.64 micrograms/ml at 6 hours after infusion. 3. The serum concentration at the ligature of uterine artery was 103.21 +/- 51.69 micrograms/ml. Among concentrations in pelvic organ/tissues 37.17 +/- 18.20 micrograms/ml in uterine cervix was the highest, followed by 35.77 +/- 7.68 micrograms/g in portio vaginalis, 26.35 +/- 14.15 micrograms/g in tube, 21.62 +/- 12.15 micrograms/g in ovary, 20.56 +/- 9.82 micrograms/g in myometrium, and 16.45 +/- 8.10 micrograms/g in endometrium, in this order. 4. From an analysis of the two-compartment model, the maximum serum concentration was 92.81 micrograms/ml, which was very high. The time of 50% reduction of concentration in beta phase was 1.21 hours. In the pelvic dead space exudate, the maximum concentration was 32.38 micrograms/ml and the time of 50% reduction was 2.44 hours. The AUC was 147 micrograms.hr/ml in serum and 201 micrograms.hr/ml in the pelvic dead space. The shift to the pelvic dead space was 137% when AUC's were used as the basis of the comparison. 5. Clinically, FMOX was excellently effective against adnexitis caused by Peptostreptococcus asaccharolyticus, intrauterine infection caused by Staphylococcus aureus, cystitis caused by Klebsiella and Escherichia coli, vaginal stump infection caused by Streptococcus and E. coli and many other infections.     

Age-dependent propranolol clearance in perfused rat liver

The effect of age on the hepatic clearance of propranolol was studied by perfusing the liver isolated from 3- to 104-week-old rats. Propranolol levels in the recirculating perfusate declined biexponentially with time in all age groups. When the liver isolated from 7-week-old rats was perfused with propranolol (1 microgram/ml, 100 ml), hepatic clearance of this drug by the perfused liver (CLperf) increased from 0.589 to 1.14 ml X min-1 X (g liver)-1 with the increase of the perfusion flow rate from 1.0 to 2.0 ml X min-1 X (g liver)-1, confirming evidence of "perfusion-limited" hepatic clearance for this drug. Furthermore, there was no initial concentration(dose)-dependence in CLperf up to 2.5 micrograms/ml (i.e. 250 micrograms/organ). The effect of age on CLperf was then investigated by perfusing the isolated liver with 1.0 micrograms/ml propranolol at 2.0 ml X min-1 X (g liver)-1. Elimination of this drug from the perfusion medium was relatively rapid in 5- to 7-week-old rats, yielding the highest CLperf in these relatively young rats [approximately 1.0 to 1.1 ml X min-1 X (g liver)-1]. In contrast, CLperf values in both immature and older rats were 0.5 ml X min-1 X (g liver)-1 or less. The in vitro intrinsic hepatic clearance estimated in 5- and 7-week-old rats was about ten times as high as that in 104-week-old rats.     

Carbamazepine-phenytoin interaction: elevation of plasma phenytoin concentrations due to carbamazepine comedication

By intrapatient comparison at constant phenytoin (PHT) dose, the effect of carbamazepine (CBZ) comedication on PHT was studied in a group of 24 epileptic outpatients. In half of the patients with steady-state PHT plasma concentration, a significant increase of this concentration was noted after CBZ was added to their regimen. Twenty percent showed clinical manifestations of acute drug toxicity initially thought to be CBZ related. The mean PHT plasma concentration for the 12 patients (22.7 +/- 5.64 micrograms/ml) as well as concentration/dose ratio for PHT (4.61 +/- 1.65 micrograms/ml plasma per mg/kg/day dose) was significantly higher (p less than 0.001) with concomitant administration of CBZ than when PHT was given alone: PHT concentration, 12.54 +/- 3.93 micrograms/ml and PHT concentration/dose ratio, 2.52 +/- 0.78 micrograms/ml plasma per mg/kg/day dose. Those patients with higher PHT plasma concentrations seem to be at higher risk of PHT toxicity due to CBZ comedication.