Bioavailability of tobramycin after oral delivery in FVB mice using CRL-1605 copolymer, an inhibitor of P-glycoprotein

Tobramycin is an aminoglycoside used in the treatment of infection against gram-negative bacteria. Tobramycin cannot be delivered orally probably due to efflux of drug by a P-glycoprotein pump in the brush border of the small intestine. In this report we demonstrate oral delivery of tobramycin in FVB mice using CRL-1605 copolymer as a vehicle. This copolymer is known to inhibit P-glycoprotein. Two different doses of tobramycin (25 mg/kg and 200 mg/kg) were used. The concentration of CRL-1605 copolymer was 132 mg/kg. The liquid formulation was fed to mice by gavage and serum tobramycin concentrations were measured after one and two hours using the fluorescence polarization immunoassay. We observed significant increases in serum tobramycin concentrations when the drug was delivered orally with the copolymer compared to when the drug was delivered alone. We also performed a bioassay using Bacillus subtilis to confirm antibacterial effect of tobramycin in mice sera. This was to ensure that tobramycin did not undergo structural change during oral absorption when delivered in the copolymer vehicle. We observed minimal inhibition in growth of Bacillus subtilis in sera obtained from mice fed with tobramycin alone. In contrast, we observed almost complete inhibition of growth (most specimens) in sera obtained from mice fed with tobramycin in the presence of CRL-1605 copolymer. We conclude that tobramycin delivered orally in mice using copolymer 1605 is also bioactive.     

Amikacin sulfate in the cat: serum, urine and uterine tissue concentrations

Puerperal metritis and pyometra in non-breeding cats is frequently caused by gram-negative bacteria that are resistant to a variety of antibiotics. Amikacin has been found to be effective against pathogens associated with uterine infections in the mare and the woman, but its efficacy has not been studied in the cat. Serum concentrations of amikacin were determined in healthy adult cats (six male and six female) after administration of 5, 10, and 20 mg/kg body weight of amikacin sulfate, each dose given subcutaneously (s.c.), intramuscularly (i.m.) and intravenously (i.v.) to each of the cats using a repeat treatment design. In a subsequent experiment, the six females were given 10 mg/kg s.c. amikacin and samples of blood, urine and full-thickness uterine wall were taken at 40 and 120 minutes after treatment. Mean serum concentrations of amikacin peaked between 30 and 45 minutes after i.m. injection and between 45 and 60 minutes after s.c. injections. The serum amikacin concentration curves were similar regardless of dose or administration route except for a slightly longer retention time after the 20 mg/kg dose given i.m. and s.c. After s.c. injection of 10 mg/kg, the mean uterine concentration of amikacin at two hours after treatment was 4.1 ug/g; the concurrent mean serum concentration was 18.6 ug/ml.     

Lethal quercetin-digoxin interaction in pigs

Digoxin is a popular cardiac glycoside with very narrow therapeutic range. Quercetin is an ubiquitous antioxidant flavonoid. Digoxin is a substrate of P-glycoprotein (P-gp), a multi-drug efflux transporter, and quercetin was reported to be a modulator of P-gp. The aim of this study was to investigate the effect of quercetin on the absorption and disposition of digoxin in pigs. Pigs were orally given digoxin (0.02 mg/kg) with and without quercetin in crossover designs. The blood was collected via jugular vein and fluorescence polarization immunoassay was used to determine the serum concentration of digoxin. The pharmacokinetic parameters were calculated using WINNONLIN. The paired Student's t-test was used for statistical comparison. The coadministration of 50 mg/kg quercetin unexpectedly resulted in sudden death of two among three pigs within 30 min after digoxin administration. The coadministration of 40 mg/kg quercetin significantly elevated the C_max of digoxin by 413% and increased the AUC_0-t by 170%. The results indicated that a very serious pharmacokinetic interaction occurred between quercetin and digoxin. The concomitant administration of digoxin and quercetin or quercetin-containing herbs and dietary supplement should be avoided.     

Intestine may be a major site of action for the apoA-I mimetic peptide 4F whether administered subcutaneously or orally

To determine if the dose of peptide administered or the plasma level was more important, doses of 0.15, 0.45, 4.5, or 45 mg/kg/day of the peptide D-4F were administered orally or subcutaneously (SQ) to apoliptotein (apo)E null mice. Plasma levels of peptide were ～1,000-fold higher when administered SQ compared with orally. Regardless of the route of administration, doses of 4.5 and 45 mg/kg significantly reduced plasma serum amyloid A (SAA) levels and the HDL inflammatory index (P < 0.0001); doses of 0.15 or 0.45 mg/kg did not. A dose of 45 mg/kg/day administered to apoE null mice on a Western diet reduced aortic atherosclerosis by ～50% (P < 0.0009) whether administered orally or SQ and also significantly reduced plasma levels of SAA (P < 0.002) and lysophosphatidic acid (P < 0.0009). Remarkably, for each dose administered, the concentration and amount of peptide in the feces was similar regardless of whether the peptide was administered orally or SQ. We conclude: i) the dose of 4F administered and not the plasma level achieved determines efficacy; ii) the intestine may be a major site of action for the peptide regardless of the route of administration.     

Capsiate, a nonpungent capsaicin analog, increases endurance swimming capacity of mice by stimulation of vanilloid receptors

We investigated the effect of capsiate, a nonpungent natural capsaicin analog, on the swimming capacity of mice in an adjustable-current water pool. Male BALB/c mice orally given capsiate (10 mg/kg) were able to keep swimming longer before exhaustion than the control mice. After 30 min of swimming, the residual glycogen in the gastrocnemius muscle was higher, the serum free fatty acid concentration tended to be higher, and the serum lactic acid concentration was significantly lower in the capsiate-administered mice. The value for the respiratory exchange ratio of the capsiate group was significantly lower during both resting and treadmill running. These physiological differences were abolished by administering the vanilloid receptor antagonist, capsazepin (0.17 mmol/kg, i.p.). The mice were not averse to the capsiate solution during a 4-h two-bottle choice test. These results suggest that the oral administration of capsiate enhanced fat oxidation and spared carbohydrate utilization, and consequently increased the endurance swimming capacity of the mice via stimulation of their vanilloid receptors. Practical application of capsiate is expected.     

Aggregation properties of a HPMA-camptothecin copolymer in isotonic solutions

Copolymers of camptothecin (CPT) and [N-(2-hydroxypropyl) methacrylamide] (HPMA) are novel anticancer drugs that show improved pharmacological profile in animal models as compared to the free drug CPT. We investigate here the aggregation properties of a HPMA-glycyl-6-aminohexanoyl-glycyl-CPT copolymer (20,000 Da). The molecular size of HPMA-copolymer CPT is followed over 5 orders of magnitudes of concentration in isotonic buffer by measuring either the time resolved fluorescence anisotropy (FA) of CPT or the autocorrelation function of the light scattered by the copolymer. A detailed analysis of these data suggests the presence of elongated structures with axial ratio 3 in the range 0.1–0.5 μg/ml and aggregates with association number higher than 2 in more concentrated solutions (up to 10 mg/ml). The binding affinity of HPMA-copolymer CPT for serum albumin is inversely dependent on the degree of aggregation of the copolymer. We also show that the copolymer concentration in plasma from mice treated with an active, non-toxic, dose of HPMA-copolymer CPT, decreases from 3 to 0.01 mg/ml in 72 h. In the same range of concentrations in vitro, we do not detect hydrophobic aggregates of polymers with high (>3) association number. Our study indicates that the circulating HPMA-copolymer CPT in mice should not undergo extensive aggregation and should interact with serum albumin more weakly than free CPT.     

In vivo cytogenetic effects of a commercially formulated mixture of cypermethrin and quinalphos in mice

In vivo cytogenetic effects of commercially formulated cypermethrin (CYP, synthetic pyrethroid insecticide) and/or quinalphos (QUI, organophosphate insecticide), generally used in combination, were examined through chromosomal aberrations (CA) and micronucleus test (MT) in mice. Male mice were orally gavaged to a single dose of CYP/QUI commercial mixture (22, 44 or 67 mg/kg b.wt.) for 24h (CA) or 48 h (MT). Based on the concentrations of active ingredients of CYP and QUI present in the test doses of CYP/QUI mixture, mice were orally exposed to 0.66, 1.32 and 2 mg/kg of CYP or 4.4, 8.8 and 13.4 mg/kg of QUI. For reference, a group of five mice was intraperitoneally administered to cyclophosphamide (20 or 50 mg/kg) or orally gavaged to peanut oil for vehicle control. Exposure of CYP/QUI mixture inhibited the mitotic index (MI) and induced CA in a dose-dependent manner at 24 h; however, significant (p<0.01 or 0.001) frequencies of CA were observed at 44 mg/kg onwards, whereas inhibition of MI at 67 mg/kg. Independent exposure of QUI at 8.8 mg/kg onwards also significantly (p<0.01 or 0.001) inhibited MI and induced CA, whereas CYP at 2 mg/kg (highest concentration in CYP/QUI mixture) inhibited MI significantly but failed to induce CA. Chromatid breaks and fragments found to be frequent aberrations in all the test groups. Treatment of CYP/QUI mixture also induced micronucleus formation dose-dependently at 48 h, yet statistically significant (p<0.001) frequencies of micronucleated polychromatic erythrocytes (MNPCE) were observed at 44 mg/kg onwards. QUI (8.8 and 13.4 mg/kg) alone also induced significant frequencies of MNPCE, whereas frequencies of MNPCE observed with the CYP even at 2 mg/kg were comparable to that of vehicle control. Present findings indicate the genotoxicity potential of CYP/QUI mixture and suggest that the simultaneous presence of the toxic doses of CYP and QUI can lead to synergistic genotoxicity in mice and may pose mutagenic risk in human beings.     

Interaction between diazepam and oral antidiabetic agents on serum glucose,insulin and chromium levels in rats

This study was undertaken to investigate the effect of diazepam in the presence and absence of glibenclamide, metformin or their combination on serum levels of glucose, insulin and chromium in rats. Results indicated that diazepam (10 mg/kg i.p.) induced marked hyperglycaemic effects in hyperglycaemic rats. This effect was associated with significant reductions in serum chromium levels and insignificant reduction in serum insulin levels. Diazepam-induced hyperglycaemia was counter-acted by concurrent administration of glibenclamide (5 mg/kg orally), metformin (500 mg/kg orally) or their combination. The effect of diazepam on serum chromium level was counteracted partially by administration of glibenclamide and augmented in the presence of metformin or its combination with glibenclamide. It is concluded that the diazepam-induced hyperglycaemia, as well as the hypoglycaemic effect of glibenclamide, might be related to changes in serum chromium levels.     

Interferon-inducing and immunostimulating activity of bonafton in an experiment

It was shown for the first time that the antiviral drug bonafton administered orally to nonlinear albino mice in single doses of 5, 12.5 and 25 mg/kg induced production of interferon in the animal blood serum. The maximum interferon titer of 160-320 IU/ml was observed 18 hours after the drug administration in a dose of 12.5 mg/kg. In low doses of 5 to 12.5 mg/kg bonafton increased the nonspecific resistance of the mice to experimental viral infections when administered orally in single doses not earlier than 2 weeks prior to the contamination. The ability of the drug to stimulate the host protective forces probably plays a certain role in the mechanism of its therapeutic action in severe viral infections of man such as severe recurring ophthalmic herpes, genital herpes, Beh?et's disease, Melkersson-Rosenthal syndrome and others.     

alpha-Tocopherol protects against alpha-naphthylisothiocyanate-induced hepatotoxicity in rats less effectively than melatonin

The protective effect of alpha-tocopherol (alpha-Toc), which exerts antioxidant and anti-inflammatory actions, against alpha-naphthylisothiocyanate (ANIT)-induced hepatotoxicity in rats was compared with that of melatonin because orally administered melatonin is known to protect against ANIT-induced hepatotoxicity in rats through its antioxidant and anti-inflammatory actions. Rats intoxicated once with ANIT (75 mg/kg, intraperitoneal (i.p.)) showed liver cell damage and biliary cell damage with cholestasis at 24 h, but not 12 h, after intoxication. ANIT-intoxicated rats received alpha-Toc (100 or 250 mg/kg) or melatonin (100 mg/kg) orally at 12 h after intoxication. The alpha-Toc administration protected against liver cell damage in ANIT-intoxicated rats, while the melatonin administration protected against both liver cell damage and biliary cell damage with cholestasis. ANIT-intoxicated rats had increased hepatic lipid peroxide concentration and myeloperoxidase activity at 12 and 24 h after intoxication. ANIT-intoxicated rats also had increased serum alpha-Toc and non-esterified fatty acid (NEFA) concentrations at 12 and 24 h after intoxication and increased serum triglyceride and total cholesterol concentrations at 24h. The administration of alpha-Toc to ANIT-intoxicated rats increased the hepatic alpha-Toc concentration with further increase in the serum alpha-Toc concentration and attenuated the increased hepatic lipid peroxide concentration and myeloperoxidase activity and serum NEFA concentration at 24 h after intoxication. The melatonin administration did not affect the hepatic alpha-Toc concentration but attenuated the increased hepatic lipid peroxide concentration and myeloperoxidase activity and serum alpha-Toc, NEFA, triglyceride, and total cholesterol concentrations at 24 h after ANIT intoxication. These results indicate that orally administered alpha-Toc protects against ANIT-induced hepatotoxicity in rats possibly through its antioxidant and anti-inflammatory actions less effectively than orally administered melatonin.     

Endometrial levels of amikacin in the mare after intrauterine infusion of amikacin sulfate

Amikacin sulfate,^e a semi-synthetic aminoglycoside antibiotic derived from kanamycin, is a broad spectrum antibiotic particularly effective against gram-negative organisms. With this spectrum of activity, amikacin may be an effective treatment for equine metritis.The purpose of this study was to determine the level of amikacin in the endometrium after intrauterine infusion. For three consecutive days, four mares were infused with 2.0 gms once a day and four others were infused with 3.0 gms once a day.Biopsy results indicate that amikacin is readily absorbed into the equine endometrium. The 3.0 gm dose appears to have no therapeutic advantage over the 2.0 gm dose. Amikacin could not be detected in the serum after intrauterine infusion.     

沙棘籽渣水提物对正常和糖尿病小鼠血糖的影响

本文研究了沙棘籽渣水提物(Aqueous extract of seabuckthorn seed residues,ASSR)对正常及糖尿病小鼠血糖、血脂代谢的影响。首先采用ASSR灌胃昆明种小鼠的急性毒性试验评价了ASSR的安全性;继而以250mg/kg和500 mg/kg剂量的ASSR连续灌胃正常小鼠3周;以250、500和800 mg/kg剂量的ASSR连续灌胃Al-loxan诱导的糖尿病小鼠3周,监测血糖,测定体重、血清胰岛素、总胆固醇和甘油三酯水平。结果显示:ASSR的LD50大于9.8 g/kg体重;连续给药3周,ASSR对正常小鼠的血糖和血脂代谢没有明显影响,但能明显降低糖尿病小鼠的血清葡萄糖和甘油三酯水平。上述结果表明:ASSR的LD50大于5 g/kg体重,按WHO急性毒性分级标准属于实际无毒级,其在实验性1型糖尿病小鼠模型上具有降血糖和降甘油三酯活性。     

The effect of different doses of cisplatin on the pharmacokinetic parameters of cefepime in mice

The simulation of human serum levels is essential in animal models to extrapolate the experimental results to clinical practice. Administration of a nephrotoxic drug such as cisplatin can be used to cause renal dysfunction as an approach to mimic human serum levels of renally excreted drugs. We aimed to determine the dose of cisplatin that did not affect the survival rate of mice and to achieve human-like serum concentrations of cefepime. Different doses of cisplatin (0, 10, 14, 18, 22 and 26 mg/kg) were given by intraperitoneal (i.p.) injection to mice three days prior to the i.p. administration of 80 mg/kg cefepime. With cisplatin doses of 18 and 22 mg/kg, the half-life of cefepime was significantly prolonged (P < 0.001) and all mice survived. The pretreatment with 26 mg/kg cisplatin significantly decreased survival (P = 0.001), but the half-life of cefepime was not significantly longer than of 18 mg/kg cisplatin. Serum levels of cefepime after the pretreatment with 18 mg/kg cisplatin were comparable to published human data. The administration of cisplatin appears to be a suitable method in mice for simulating human serum concentrations of renally excreted drugs.     

The use of ginger (Zingiber officinale Rosc.) as a potential anti-inflammatory and antithrombotic agent

The effect of an aqueous extract of ginger (Zingiber officinale) on serum cholesterol and triglyceride levels as well as platelet thromboxane-B(2) and prostaglandin-E(2) production was examined. A raw aqueous extract of ginger was administered daily for a period of 4 weeks, either orally or intraperitoneally (IP) to rats. Fasting blood serum was investigated for thromboxane-B(2), prostaglandin-E(2), cholesterol and triglycerides. A low dose of ginger (50 mg/kg) administered either orally or IP did not produce any significant reduction in the serum thromboxane-B(2) levels when compared to saline-treated animals. However, ginger administered orally caused significant changes in the serum PGE(2) at this dose. High doses of ginger (500 mg/kg) were significantly effective in lowering serum PGE(2) when given either orally or IP. However, TXB(2) levels were significantly lower in rats given 500 mg/kg ginger orally but not IP. A significant reduction in serum cholesterol was observed when a higher dose of ginger (500 mg/kg) was administered. At a low dose of ginger (50 mg/kg), a significant reduction in the serum cholesterol was observed only when ginger was administered IP. No significant changes in serum triglyceride levels were observed upon administration of either the low or high dose of ginger. These results suggest that ginger could be used as an cholesterol-lowering, antithrombotic and anti-inflammatory agent.     

Antitumor effect of photodynamic therapy with zincphyrin, zinc-coproporphyrin III, in mice

We studied the antitumor effects of photodynamic therapy (PDT) with Zincphyrin, coproporphyrin III with zinc, derived from Streptomyces sp. AC8007, in vitro and in vivo. The photokilling effect of Zincphyrin in the presence of 0.78-100 microg/ml with visible light of 27.2 mW x min/cm2 for 10 min was lower than the hematoporphyrin (Hp) used as a control with L5178Y or sarcoma-180 cells. On the other hand, Zincphyrin apparently reduced tumor growth after intraperitoneal injection at doses of 12.5-50 mg/kg with light irradiation of 75.48 mW x min/cm2 for 10 min in sarcoma-180-bearing mice. Although no mice treated with Zincphyrin died, Hp did cause the death of mice. In B-16 melanoma-bearing mice, both Zincphyrin and Hp had a similar phototherapic effect. Further improvement of the phototherapic effect was observed with the continuous administration of Zincphyrin at 12.5 mg/kg per day for 3 days. The concentration of Zincphyrin in the serum reached a maximum level of 16 microg/ml within 20 min, and the concentration remained at 4.2 microg/ml at 1 hour after the onset of treatment, indicating its rapid action in the body. No animals died after the intraperitoneal administration of Zincphyrin at 100 mg/kg plus exposure to light of 10 mW x min/cm2 for 2 hours, and the body weight of the mice did not decrease. In contrast, all animals receiving 100 mg/kg of Hp under the same conditions died. These results indicate that Zincphyrin would be a useful photosensitizer with low phototoxicity.     

Modulatory effects of one polysaccharide from Acanthopanax senticosus in alloxan-induced diabetic mice

One water-soluble polysaccharide ASP was purified from Acanthopanax senticosus and its physicochemical properties were confirmed by the combination of chemical and instrumental analysis. ASP administered orally at three doses (100, 200 and 400 mg/kg body weight) could significantly decrease the concentration of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein (LDL) cholesterol levels except for high density lipoprotein (HDL) cholesterol level and the relative ratio (HDL/TC) in alloxan-induced diabetic mice, compared with the diabetic controls without drug treatment, comparable with that of diabetic mice treated with metformin. Furthermore, ASP could obviously increase the body weight and serum insulin level and reduce the fasting blood glucose (FBG) levels, especially at dose of 200 mg/kg. The data demonstrated ASP at the certain did often exhibit the optimal protective effect in alloxan-induced diabetic mice. It is promising that ASP may serve as a drug candidate or a healthcare food for diabetic therapy or protection.     

Comparative study of the effectiveness of amikacin and streptomycin in experimental tularemia

In vitro study on antibacterial activity of amikacin in comparison to that of streptomycin revealed a high sensitivity of tularemia microbes of three geographical races to it. Amikacin showed a high therapeutic activity in treatment of albino mice infected with tularemia. The prospects of amikacin use in prophylaxis and treatment of tularemia are defined by its antibiotic activity against streptomycin-resistant forms of the tularemia causative agent.     

不同剂量炔雌醚对小鼠器官鲜重、繁殖生理和肝肠CYP3A4酶含量的影响

为探究不同剂量炔雌醚对小鼠器官、激素和肝肠药解酶的影响,分别以0.008 mg/kg、0.04 mg/kg、0.2 mg/kg、1.0 mg/kg和5.0 mg/kg的炔雌醚油溶液连续3d灌胃小鼠,首次给药7d后解剖取材,检测其器官鲜重、雄鼠精子数量、血清中激素浓度、小肠和肝脏中CYP3 A4酶含量的变化.结果 发现:...     

Role of P-Glycoprotein in the Blood-Brain Transport of Colchicine and Vinblastine

Abstract: Classically, drug penetration through the blood-brain barrier depends on the lipid solubility of the substance, except for some highly lipophilic drugs, like colchicine and vinblastine, both substrates of P-glycoprotein, a drug efflux pump present at the luminal surface of the brain capillary endothelial cells. Colchicine and vinblastine uptake into the brain was studied in the rat using the in situ brain perfusion technique and two inhibitors of P-glycoprotein, verapamil and SDZ PSC-833. When rats were pretreated with PSC-833 (10 mg/kg, intravenous bolus), colchicine and vinblastine uptake was enhanced 8.42- and 9.08-fold, respectively, in all the gray areas of the rat brain studied. The mean colchicine distribution volume was increased from 0.67 ± 0.41 to 5.64 ± 0.70 µl/g and vinblastine distribution volume from 2.74 ± 1.15 to 24.88 ± 4.03 µl/g. When rats were pretreated with verapamil (1 mg/kg, intravenous bolus), colchicine distribution volume was increased 3.70-fold. The increase in colchicine and vinblastine did not differ between the eight brain gray areas. PSC-833 and verapamil pretreatment had no influence on the distribution volume of either drug in the choroid plexus. Nevertheless, distribution volumes remained small, considering the highly lipophilic nature of the substances. We suggest that P-glycoprotein is either only partially inhibited (difficulty of fully saturating P-glycoprotein, especially under in vivo conditions) or not the only barrier to these two drugs.     

Effect of feeding of a cholesterol-reducing bacterium, Eubacterium coprostanoligenes, to germ-free mice

Twelve germ-free mice were used to evaluate the effect of orally administered Eubacterium coprostanoligenes (ATCC 51222) on serum cholesterol concentration. After 1 week of bacterial administration, serum cholesterol concentration of the experimental group (204.9 +/- 5.3 mg/dl, mean +/- SEM) tended to be lower than that of controls (213.7 +/- 5.9 mg/dl, mean +/- SEM). The hypocholesterolemic effect, however, was transient. Greater coprostanol-to-cholesterol ratios in feces of bacteria-fed mice also indicated a transient cholesterol-reducing action of E. coprostanoligenes in the intestine. Eubacterium coprostanoligenes did not colonize the intestine of E. coprostanoligenes-fed mice. Results indicate that the transient occurrence of E. coprostanoligenes in the digestive tract of E. coprostanoligenes-fed mice may decrease plasma cholesterol concentration, but colonization of the tract depends on monoassociation with another bacterium. Results also indicate that feeding of E. coprostanoligenes decreases blood cholesterol concentration.