Polymorphism, pseudopolymorphism, and amorphism of peracetylated alpha-, beta-, and gamma-cyclodextrins

Polymorphism, pseudopolymorphism, and amorphism of hexakis(2,3,6-tri-O-acetyl)-alpha-cyclodextrin (TAalphaCyD), heptakis(2,3,6-tri-O-acetyl)-beta-cyclodextrin (TAbetaCyD), and octakis(2,3,6-tri-O-acetyl)-gamma-cyclodextrin (TAgammaCyD) were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffractometry (XRPD), Fourier transform infrared spectroscopy (FTIR) and optical microscopy. An anhydrous and a bi-hydrate crystalline forms of TAalphaCyD, two monotropic anhydrous polymorphs and three pseudopolymorphs (i.e. methanolate, hydrate, and isopropanolate-hydrate) of TAbetaCyD, as well as two monotropic anhydrous polymorphs and isostructural pseudopolymorphs (e.g. hydrate and isopropanolate-hydrate) of TAgammaCyD were isolated and characterized. The amorphous forms of each TACyD were also obtained. Thermal data for desolvation of TAalphaCyD.2H2O and TAbetaCyD.CH3OH were reconciled with their crystal packing features. Melting temperatures and enthalpies of the crystalline forms of each TACyD can be referred to for possible solid-state interactions with drugs.     

Synthesis,anti-inflammatory,analgesic, and antibacterial activities of some triazole,triazolothiadiazole, and triazolothiadiazine derivatives

This study is concerned with the synthesis of new 1,2,4-triazoles, 1,3,4-thiadiazoles, and 1,3,4-thiadiazines derivatives. Derivatives 3a–i were obtained by condensation of 4-amino-3-(4-pyridine)-5-mercapto-1,2,4-triazole 1 with the appropriate aldehyde. Compounds 4a–i were synthesized in a one pot reaction involving compounds 3a–i, formaldehyde, and morpholine. Condensation of compound 1 with the appropriate acids or 4-substituted phenacyl bromide gave compounds 6a–d and 8a–f respectively. The chemical structures of the newly synthesized derivatives were elucidated using different spectral and elemental methods of analysis. All compounds were evaluated for their anti-inflammatory activity and the most potent derivatives were tested for their analgesic activity using indomethacin as a reference drug. In addition, ulcerogenicity and LD₅₀ for the most active compounds were evaluated. Moreover, the antibacterial activities of the newly synthesized derivatives were investigated.     

New synthesis of benzo-delta-carbolines, cryptolepines, and their salts: in vitro cytotoxic, antiplasmodial, and antitrypanosomal activities of delta-carbolines, benzo-delta-carbolines, and cryptolepines

The paper describes, in its first part, a new synthesis of benzo-delta-carbolines, cryptolepines, and their salts. The strategy is based on the association between halogen-dance and hetero-ring cross-coupling. It is fully convergent and regioselective with interesting overall yields from 27% to 70%. A halogen-dance mechanism in quinoline series is also proposed. The formal synthesis of potential antimalarial compounds and the first total synthesis of 11-isopropylcryptolepine are also described. In the second part, cytotoxic activity against mammalian cells and activities against Plasmodium falciparum and Trypanosoma cruzi of benzo-delta-carbolines and delta-carbolines were evaluated in vitro to study the structure-activity relationships. For benzo-delta-carbolines, methylation at N-5 increases the cytotoxic and antiparasitic activities. A further alkylation on C-11 generally increases the cytotoxic activity but not the antiparasitic activity, cryptolepine and 11-methylcryptolepine being the most active on both parasites. Taking advantage of the fluorescence of the indoloquinoline chromophore, cryptolepine was localized by fluorescence microscopy in parasite DNA-containing structures suggesting that these compounds act through interaction with parasite DNA as proposed for cryptolepine on melanoma cells. For delta-carbolines, methylation at N-1 is essential for the antimalarial activity. 1-Methyl-delta-carboline specifically accumulates in the intracellular parasite. It has weak cytotoxic activity and can be considered as a potential antimalarial compound.     

Stereospecific and circadian-phase-dependent kinetic behavior of d,l-, l-, and d-propranolol in plasma, heart, and brain of light--dark-synchronized rats

In light--dark-synchronized male rats, the kinetic behavior of d,l-, l-, and d-propranolol after single (1.78 and 8.89 mg/kg) or multiple drug administration (6 X 8.89 mg/kg) was studied in plasma, heart, and brain both in the light period (L) and in the dark period (D). With either dosage regimen the kinetics of racemic propranolol displayed a temporal dependency, elimination half-lives in plasma, heart, and brain being shorter during D than during L. This was observed with the stereoisomers only after single drug application with no circadian phase dependency at steady-state concentrations. On the other hand, the kinetic behavior of l- and d-propranolol exhibited pronounced stereospecificity in that t1/2 Beta, Vdbeta, plasma clearance, and drug accumulation in heart and brain were greater for l-propranolol than for the d-isomer. Stereospecific differences in t1/2 beta and elimination rate were more pronounced during D. In the light of the flow-dependent hepatic extraction of propranolol it is unlikely that daily variations in microsomal liver enzyme activity are responsible for the chronopharmacokinetics of propranolol. It is assumed that daily variations in liver blood flow, which is more effectively reduced by beta-receptor blockade in the period of increased sympathetic tone during D, are mainly responsible for the chronopharmocokinetics of the therapeutically used d,l-propranolol.     

PCP, THC, ethanol, and morphine and consumption of palatable solutions

Water-deprived rats were given daily opportunities (2.0-hr sessions) to take water or a sweet solution (20% or 24% sugar-water). After stable intakes of each fluid were achieved, the effects of phencyclidine hydrochloride (PCP), delta-9-tetrahydrocannabinol (THC), ethanol (E), and morphine (M) on intakes were tested. PCP, THC, and M all enhanced intake of the sweet solution, while E produced varying effects across doses tested. With other rats, nearly the same procedure was used except that the test solution presented with water was 0.9% sodium chloride. Doses of PCP enhanced intake of the salty solution. These data, combined with the data from similar studies of the effects of opioids and benzodiazepines, indicate that a wide variety of agents that are self-administered also modify intake of ingesta.     

Pharmacokinetics of Liquiritigenin in Mice,Rats, Rabbits,and Dogs,and Animal Scale-Up

Pharmacokinetics of liquiritigenin (LQ) and its two glucuronide metabolites, M1 and M2, in mice, rats, rabbits, and dogs and animal scale-up of the pharmacokinetic parameters of LQ were evaluated. After intravenous administration of LQ, the AUC (AUC_0?t) values of LQ, M1, and M2 were proportional to LQ doses in all animals studied. Animal scale-up of some pharmacokinetic parameters of LQ was performed based on the parameters after its intravenous administration (20 mg/kg; in the linear pharmacokinetic range) to the four species. Linear relationships were obtained (r > 0.968) between log CL (or CL/f_u) (L/h) and log species body weight (W) (kg) [CL (or CL/f_u) = 3.29 (34.0) W^{0.723 (0.789)}] and log V_ss (or V_ss/f_u) (L) and log W (kg) [V_ss (or V_ss/f_u) = 0.340 (3.52) W^{0.882 (0.948)}]. Interspecies scale-up of plasma concentration–time data of LQ using apolysichron (complex Dedrick plots) resulted in similar profiles, and plasma concentration–time profile of humans were predicted using the well-fitted four animal data. Our results indicate that the LQ data obtained from laboratory animals could be utilized to generate preliminary estimates of the pharmacokinetic parameters of LQ in humans. These parameters can serve as guidelines for better planning of clinical studies. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:4327–4342, 2009     

Comparison of natriuretic, uricosuric, and antihypertensive properties of tienilic acid, bendrofluazide, and spironolactone.

The antihypertensive properties of the new diuretic tienilic acid were investigated. Thirteen previously untreated hypertensive patients took part in a double-blind crossover study in which 30 days' treatment with tienilic acid 250 mg, bendrofluazide 5 mg, and spironolactone 100 mg were compared. Bendrofluazide caused the greatest natriuresis on the first treatment day and the most rapid fall in blood pressure. The ultimate antihypertensive effect of all three drugs was similar. Tienilic acid caused a noticeable reduction in serum urate concentrations and a rise in urate clearance, in contrast to the other two agents, which caused slight urate retention. Tienilic acid and bendrofluazide caused falls and spironolactone a rise in plasma potassium concentrations. No untoward effects were seen from any of the drugs. It is concluded that tienilic acid is a moderately potent diuretic that lowers plasma urate concentrations. It may be the drug of first choice for hypertensive patients who already have gout or are likely to develop it when taking thiazide diuretics.     

Combination action of sisomicin, dibekacin and cefotetan, cefotaxime, latamoxef, and cefsulodin against Escherichia coli, Serratia marcescens, and Pseudomonas aeruginosa

The combined actions of sisomicin (SISO), dibekacin (DKB) and cefotetan (CTT), cefotaxime (CTX), latamoxef (LMOX), cefsulodin (CFS) against E coli KC-14, S. marcescens T-55 and P. aeruginosa E-2 were studied. The following results were obtained. The combination of SISO-CTT, SISO-CTX, SISO-LMOX, SISO-CFS, DKB-CTT, DKB-CTX, DKB-LMOX and DKB-CFS using the checker board dilution method on E. coli KC-14, S. marcescens T-55, P. aeruginosa E-2 were found to have a synergistic effect and the minimum FIC index values were 0.26--0.50 for SISO and 0.28--0.75 for DKB, respectively. With the killing kinetic method, all combinations tested showed a synergistic effect.     

Storage,release, uptake,and inactivation of purines

Adenine nucleotides are released into the interstitial space during platelet thrombus formation and neurotransmission. ATP has also been reported to be released from the heart and endothelial cells in some studies. Ecto ATPase, ADPase, and 5′-nucleotidase activities capable of hydrolyzing ATP sequentially to adenosine are present in many cell types and may serve to terminate the actions of the nucleotides. The opposing effects of adenosine and ATP on the same cell types have suggested a modulatory role for adenosine of the actions of extracellular ATP and that the rates of hydrolysis of nucleotides might be regulated. Consistent with this it has been found that the balance between feedforward inhibition of 5′-nucleotidase by ADP and/or ATP and preferential delivery of AMP from ADPase to 5′-nucleotidase determines the rate of adenosine production and that this differs in different cell types. Alternatively, adenosine may be produced intracellularly as a result of an imbalance between energy demand and supply. There are at least two different cytosolic forms of 5′-nucleotidase. Degradation of ATP during increased metabolic activity results in an increase in intracellular AMP concentration. Either cytosolic enzyme has a high KM (2–5 mM) and would thus respond to this increase with a proportional rise in the rate of adenosine production. The nucleoside transporter is essential to allow the diffusion of adenosine to extracellular receptor sites. In general, adenosine must be taken up via the nucleoside transporter before it is inactivated either by phosphorylation by adenosine kinase in the micromolar range or by deamination by adenosine deaminase at higher concentrations. © 1993 Wiley-Liss, Inc.     

Pharmacokinetics, tissue distribution, and excretion of sitafloxacin, a new fluoroquinolone antibiotic, in rats, dogs, and monkeys

The pharmacokinetics, tissue distribution and excretion of sitafloxacin (CAS 127254-12-0, DU-6859a) were investigated in rats, dogs, and monkeys following single intravenous or single oral administration of 14C-labelled sitafloxacin at a dose of 4.69 mg/kg. Following single administration of the oral dose, serum concentrations of radioactivity peaked at 0.5 h in rats, 2.3 h in dogs, and 2.5 h in monkeys. The apparent absorption ratios of 14C-sitafloxacin based on the AUC0-infinity were 31%, 51%, and 93% in rats, dogs, and monkeys, respectively. In rats, the drug-related radioactivity had been distributed to most organs and tissues 30 min after oral dosing, and had been essentially eliminated after 24 h. The highest levels of radioactivity were observed in the kidneys and liver, whereas the concentrations in the cerebrum and spinal cord were much lower than the serum value. The urinary recoveries of radioactivity after intravenous dosing were 45.5 % in rats, 32.3 % in dogs, and 77.8 % in monkeys. In bile duct-cannulated rats, 57.8 % of the orally administered radioactivity was excreted in the bile within 48 h, and at least 45 % of the sitafloxacin-related material secreted in the bile was re-absorbed from the gastrointestinal tract. These results indicate that sitafloxacin is rapidly absorbed and widely distributed into various tissues. Sitafloxacin-related material is eliminated primarily through both renal and biliary excretion in rats, and possibly in dogs, whereas renal excretion is the major route of elimination in monkeys.     

Metabolism and disposition of gemcitabine, and oncolytic deoxycytidine analog, in mice, rats, and dogs.

Gemcitabine, 2'-deoxy-2',2'-difluorocytidine, is a broad spectrum oncolytic compound with antitumor activity in solid tumor models. The pharmacokinetics, metabolism, and disposition of gemcitabine was examined in mice, rats, and dogs. All three species metabolize gemcitabine by deamination to the uracil metabolite. However, deamination in the mouse and dog was more extensive than in the rat. The mouse deaminated gemcitabine rapidly with the plasma concentration maximum of the uracil metabolite of gemcitabine being attained at 15 min postdosing compared with approximately 3 and 6 hr in the dog and rat, respectively. The rapid deamination in the mouse was also reflected in the plasma half-life of the parent compound. The mouse exhibited the shortest plasma half-life, approximately 0.28 hr, contrasted with 2.14 and 1.38 hr half-lives in rat and dog, respectively. Plasma AUC for the uracil metabolite of gemcitabine was 73%, 10.5%, and 315% of that for gemcitabine in the mouse, rat, and dog, respectively. Tissue concentrations of gemcitabine-derived radioactivity in the rat and mouse indicated that gemcitabine was rapidly distributed throughout the body. Half-lives of radioactivity in tissues of both the rat and mouse were relatively short, with the longest tissue half-lives of 5.7 and 3.0 hr, respectively. Plasma protein binding is negligible in all three species. The major route of elimination is via the urine in all three species with 76-86% of the dose excreted in the first 24 hr. The predominant radiolabeled component isolated from urine was gemcitabine in the rat and its uracil metabolite in the mouse and dog.     

New antiretroviral drugs: a review of the efficacy,safety, pharmacokinetics,and resistance profile of tipranavir,darunavir, etravirine,rilpivirine, maraviroc,and raltegravir

Background: The introduction and approval of new antiretroviral agents in the US and Canada bring new opportunities and new challenges. Arguably, for the first time ever, clinicians have the drugs necessary to achieve the goal of suppressing HIV RNA to levels less than 50 copies/mL in even the most treatment-experienced patients and in those with extensive drug-limiting resistance mutations. However, the use of these new agents is complicated by many drug–drug interactions and – to some extent – pre-existing mutations. To derive maximum durability from the use of these newer drugs, a thorough understanding of their indications and limitations is critical. Objective: To thoroughly review the six most recently approved or soon-to-be-approved antiretroviral drugs in the US and Canada: tipranavir, darunavir, etravirine, rilpivirine, maraviroc, and raltegravir. Methods: Discussion of the indications for, and pharmacokinetics, resistance profile, activity, toxicity, and clinical trials results of, the six new agents. Results/conclusions: These six new agents have resulted in marked progress towards the goal of being able to provide HIV-infected individuals with the drugs necessary to achieve decades of durable suppression of HIV without substantial toxicity.     

Simultaneous measurement of bupivacaine, etidocaine, lidocaine, meperidine, mepivacaine, and methadone

A gas-liquid chromatographic method for the simultaneous measurement of bupivacaine, etidocaine, lidocaine, meperidine, mepivacaine, and methadone in serum is described. The drugs and the internal standard, prilocaine, are extracted from 1 ml of serum. The procedure involves a two-step extraction and injection of the extract into a gas chromatograph equipped with a 10-ft OV-11 glass column and a nitrogen-phosphorus detector. The temperature gradient program results in a run time of 16 min and retention times for meperidine, prilocaine (internal standard), lidocaine, etidocaine, mepivacaine, methadone, and bupivacaine of 3.8, 5.4, 6.0, 8.7, 11.0, 11.7, and 14.8 min, respectively. Standard curves for all drugs were linear over the 80 to 2,000-ng/ml range and recovery of all components averaged 97 +/- 2% with the lowest detection limit of 10 ng/ml for all drugs except meperidine and methadone, which were 20 ng/ml. The within-day coefficients of variation ranged from 12 to 8% at 500 ng/ml. The day-to-day coefficients of variation of the slope and intercept values ranged from 2 to 0% and 130 to 3%, respectively. Response factors of the nitrogen-specific collector varied with the drug analyzed and resulted in peak area variation at constant offset and attenuation of 30%. This method is intended and adequate for therapeutic monitoring of chronically treated pain patients who are being given various combinations of local anesthetic and/or narcotic agents.     

Absorption, distribution, metabolism, and excretion of ximelagatran, an oral direct thrombin inhibitor, in rats, dogs, and humans.

The absorption, metabolism, and excretion of the oral direct thrombin inhibitor, ximelagatran, and its active form, melagatran, were separately investigated in rats, dogs, and healthy male human subjects after administration of oral and intravenous (i.v.) single doses. Ximelagatran was rapidly absorbed and metabolized following oral administration, with melagatran as the predominant compound in plasma. Two intermediates (ethyl-melagatran and OH-melagatran) that were subsequently metabolized to melagatran were also identified in plasma and were rapidly eliminated. Melagatran given i.v. had relatively low plasma clearance, small volume of distribution, and short elimination half-life. The oral absorption of melagatran was low and highly variable. It was primarily renally cleared, and the renal clearance agreed well with the glomerular filtration rate. Ximelagatran was extensively metabolized, and only trace amounts were renally excreted. Melagatran was the major compound in urine and feces after administration of ximelagatran. Appreciable quantities of ethyl-melagatran were also recovered in rat, dog, and human feces after oral administration, suggesting reduction of the hydroxyamidine group of ximelagatran in the gastrointestinal tract, as demonstrated when ximelagatran was incubated with feces homogenate. Polar metabolites in urine and feces (all species) accounted for a relatively small fraction of the dose. The bioavailability of melagatran following oral administration of ximelagatran was 5 to 10% in rats, 10 to 50% in dogs, and about 20% in humans, with low between-subject variation. The fraction of ximelagatran absorbed was at least 40 to 70% in all species. First-pass metabolism of ximelagatran with subsequent biliary excretion of the formed metabolites account for the lower bioavailability of melagatran.     

Pharmacokinetics,toxicokinetics, distribution,metabolism and excretion of linezolid in mouse,rat and dog

1. Linezolid (ZYVOX?), the first of a new class of antibiotics, the oxazolidinones, is approved for treatment of Gram-positive bacterial infections. 2. The aim was to determine the absorption, distribution, metabolism and excretion (ADME) of linezolid in mouse, rat and dog in support of preclinical safety studies and clinical development. 3. Conventional replicate study designs were employed in animal experiments, and biofluids were assayed by HPLC or HPLC-MS. 4. Linezolid was rapidly absorbed after p.o. dosing with an p.o. bioavailability of > 95% in rat and dog, and > 70% in mouse. Twenty-eight-day i.v./p.o. toxicokinetic studies in rat (20-200mg kg^?1 day^?1) and dog (10-80mg kg^?1 day^?1) revealed neither a meaningful increase in clearance nor accumulation upon multiple dosing. 5. Linezolid had limited protein binding (<35%) and was very well distributed to most extravascular sites, with a volume of distribution at steady-state (V_ss) approximately equal to total body water. 6. Linezolid circulated mainly as parent drug and was excreted mainly as parent drug and two inactive carboxylic acids, PNU-142586 and PNU-142300. Minor secondary metabolites were also characterized. In all species, the clearance rate was determined by metabolism. 7. Radioactivity recovery was essentially complete within 24-48h. Renal excretion of parent drug and metabolites was a major elimination route. Parent drug underwent renal tubular reabsorption, significantly slowing parent drug excretion and allowing a slow metabolic process to become rate-limiting in overall clearance. 8. It is concluded that ADME data were relatively consistent across species and supported the rat and dog as the principal non-clinical safety species.     

Pharmacokinetics,toxicokinetics, distribution,metabolism and excretion of linezolid in mouse,rat and dog

1. Linezolid (ZYVOX), the first of a new class of antibiotics, the oxazolidinones, is approved for treatment of Gram-positive bacterial infections. 2. The aim was to determine the absorption, distribution, metabolism and excretion (ADME) of linezolid in mouse, rat and dog in support of preclinical safety studies and clinical development. 3. Conventional replicate study designs were employed in animal experiments, and biofluids were assayed by HPLC or HPLC-MS. 4. Linezolid was rapidly absorbed after p.o. dosing with an p.o. bioavailability of > 95% in rat and dog, and > 70% in mouse. Twenty-eight-day i.v./p.o. toxicokinetic studies in rat (20-200mg kg(-1) day(-1)) and dog (10-80 mg kg(-1) day(-1)) revealed neither a meaningful increase in clearance nor accumulation upon multiple dosing. 5. Linezolid had limited protein binding (<35%) and was very well distributed to most extravascular sites, with a volume of distribution at steady-state (V(ss)) approximately equal to total body water. 6. Linezolid circulated mainly as parent drug and was excreted mainly as parent drug and two inactive carboxylic acids, PNU-142586 and PNU-142300. Minor secondary metabolites were also characterized. In all species, the clearance rate was determined by metabolism. 7. Radioactivity recovery was essentially complete within 24-48 h. Renal excretion of parent drug and metabolites was a major elimination route. Parent drug underwent renal tubular reabsorption, significantly slowing parent drug excretion and allowing a slow metabolic process to become rate-limiting in overall clearance. 8. It is concluded that ADME data were relatively consistent across species and supported the rat and dog as the principal non-clinical safety species.     

Thyroid hormone, glucocorticoids, and prolactin at the nexus of physiology, reproduction, and toxicology

A symposium at the 2003 Annual Meeting of the Society of Toxicology brought together an expert group of endocrinologists to review how non-reproductive hormones can affect the endocrine system. This publication captures the essence of those presentations. Paul Cooke and Denise Holsberger recapitulate the evidence of how thyroid hormones affect male and female reproduction, and reproductive development. Ray Witorsch summarizes the many effects of glucocorticoids on the reproductive system. Finally, Paul Sylvester reviews the mechanism of action of prolactin, and reminds us that this ancient hormone has many functions beyond lactation.