Pharmacokinetics and pharmacodynamics of glycyrrhetinic acid with Paeoniflorin after transdermal administration in dysmenorrhea model mice.

BACKGROUND: Glycyrrhetinic acid (GA) and paeoniflorin (PF) are the main active ingredients in Chinese peony- Liquorice Decoction, a widely used Traditional Chinese Medicine. HYPOTHESIS/PURPOSE: The aim of this work was to investigate the combinatory analgesic effect of GA and PF after percutaneous administration and to define their pharmacokinetic/pharmacodynamic (PK/PD) characteristics. STUDY DESIGN AND METHODS: GA and PF were produced to transdermal patches based on previous research, and the permeation parameters of GA and PF in the patches were investigated with in vitro experiments. Dysmenorrhea model mice were then produced to compare the analgesic effects of the patches with different proportions of GA-PF. In the in vivo assessment, the number of writhes exhibited by the dysmenorrhea mice was recorded at designated time points, and skin, muscle under skin and plasma samples were collected, for assessments of drug distribution, pharmacokinetics parameters and PK/PD characteristics. RESULTS AND CONCLUSION: In dysmenorrhea mice, GA-PF and meloxicam (the positive control drug) could relieve pain to equal degrees. Specifically, a single dose of the optimized patches (10%GA-10%PF, wt) exerted a steady analgesic effect for 48h in dysmenorrhea mice, but this effect lagged behind the changes in the plasma concentration. Evaluation with the Bliss Independence criterion revealed that the two ingredients displayed a synergistic effect. Then the PK/PD relationship of GA in this compound preparation was defined with this synergistic effect. The preparation might be suitable for topical spasmolysis and anti-inflammatory therapy.

Pharmacokinetic characterization of 2-(3-benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone, a novel 11ß-hydroxysteroid dehydrogenase type 1 inhibitor in rats.

11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) is associated with metabolic syndromes such as type 2 diabetes mellitus and obesity. A new 11ß-HSD1 inhibitor known as 2-(3-benzoyl)-4-hydroxy-1, 1-dioxo-2H-1, 2-benzothiazine-2-yl-1-phenylethanone (KR-66344) is being developed as a therapeutic agent for these metabolic diseases. The purpose of this study was to characterize the pharmacokinetics of KR-66344 to support further preclinical development. KR-66344 showed high liver microsomal stability with T1/2 values >3 h and high permeability with apparent permeability coefficients of 15.2-24.2 × 10(-6) cm/s in Caco-2 cell monolayers. KR-66344 was also strongly bound to plasma proteins (>98%). After intravenous dosing, KR-66344 exhibited low systemic clearance (0.27-0.37 L/h/kg) and a low to moderate volume of distribution at steady state (0.79-0.8 L/kg). The bioavailability and terminal half-lives of KR-66344 following oral administration were 25% and 1.7-3.3 h, respectively. In addition, KR-66344 showed dose-independent pharmacokinetics at 0.5-10 mg/kg in intravenous and oral pharmacokinetic studies.

A novel BACE inhibitor NB-360 shows a superior pharmacological profile and robust reduction of amyloid-ß and neuroinflammation in APP transgenic mice.

BACKGROUND: Alzheimer's disease (AD) is the most common form of dementia, the number of affected individuals is rising, with significant impacts for healthcare systems. Current symptomatic treatments delay, but do not halt, disease progression. Genetic evidence points to aggregation and deposition of amyloid-ß (Aß) in the brain being causal for the neurodegeneration and dementia typical of AD. Approaches to target Aß via inhibition of γ-secretase or passive antibody therapy have not yet resulted in substantial clinical benefits. Inhibition of BACE1 (ß-secretase) has proven a challenging concept, but recent BACE1inhibitors can enter the brain sufficiently well to lower Aß. However, failures with the first clinical BACE1 inhibitors have highlighted the need to generate compounds with appropriate efficacy and safety profiles, since long treatment periods are expected to be necessary in humans. RESULTS: Treatment with NB-360, a potent and brain penetrable BACE-1 inhibitor can completely block the progression of Aß deposition in the brains of APP transgenic mice, a model for amyloid pathology. We furthermore show that almost complete reduction of Aß was achieved also in rats and in dogs, suggesting that these findings are translational across species and can be extrapolated to humans. Amyloid pathology may be an initial step in a complex pathological cascade; therefore we investigated the effect of BACE-1 inhibition on neuroinflammation, a prominent downstream feature of the disease. NB-360 stopped accumulation of activated inflammatory cells in the brains of APP transgenic mice. Upon chronic treatment of APP transgenic mice, patches of grey hairs appeared. CONCLUSIONS: In a rapidly developing field, the data on NB-360 broaden the chemical space and expand knowledge on the properties that are needed to make a BACE-1 inhibitor potent and safe enough for long-term use in patients. Due to its excellent brain penetration, reasonable oral doses of NB-360 were sufficient to completely block amyloid-ß deposition in an APP transgenic mouse model. Data across species suggest similar treatment effects can possibly be achieved in humans. The reduced neuroinflammation upon amyloid reduction by NB-360 treatment supports the notion that targeting amyloid-ß pathology can have beneficial downstream effects on the progression of Alzheimer's disease.

The effect of timing of oral meloxicam administration on physiological responses in calves after cautery dehorning with local anesthesia.

Dehorning is a painful husbandry procedure that is commonly performed in dairy calves. Parenteral meloxicam combined with local anesthesia mitigates the physiological and behavioral effects of dehorning in calves. The purpose of this study was to determine the influence of timing of oral meloxicam administration on physiological responses in calves after dehorning. Thirty Holstein bull calves, 8 to 10 wk of age (28-70 kg), were randomly assigned to 1 of 3 treatment groups: placebo-treated control group (n=10), calves receiving meloxicam administered orally (1 mg/kg) in powdered milk replacer 12h before cautery dehorning (MEL-PRE; n=10), and calves receiving meloxicam administered as an oral bolus (1 mg/kg) at the time of dehorning (MEL-POST; n=10). Following cautery dehorning, blood samples were collected to measure cortisol, substance P (SP), haptoglobin, ex vivo prostaglandin E2 (PgE2) production after lipopolysaccharide stimulation and meloxicam concentrations. Maximum ocular temperature and mechanical nociceptive threshold (MNT) were also assessed. Data were analyzed using noncompartmental pharmacokinetic analysis and repeated measures ANOVA models. Mean peak meloxicam concentrations were 3.61±0 0.21 and 3.27±0.14 µg/mL with average elimination half-lives of 38.62±5.87 and 35.81±6.26 h for MEL-PRE and MEL-POST, respectively. Serum cortisol concentrations were lower in meloxicam-treated calves compared with control calves at 4 h postdehorning. Substance P concentrations were significantly higher in control calves compared with meloxicam-treated calves at 120 h after dehorning. Prostaglandin E2 concentrations were lower in meloxicam-treated calves compared with control calves. Mechanical nociceptive threshold was higher in control calves at 1h after dehorning, but meloxicam-treated calves tended to have a higher MNT at 6h after dehorning. No effect of timing of meloxicam administration on serum cortisol concentrations, SP concentrations, haptoglobin concentrations, maximum ocular temperature, or MNT was observed. However, PgE2 concentrations in MEL-PRE calves were similar to control calves after 12h postdehorning, whereas MEL-POST calves had lower PgE2 concentrations for 3 d postdehorning. These findings support that meloxicam reduced cortisol, SP, and PgE2 after dehorning, but only PgE2 production was significantly affected by the timing of meloxicam administration.

Colonic luminal surface retention of meloxicam microsponges delivered by erosion based colon-targeted matrix tablet.

The work was aimed at developing calcium-pectinate matrix tablet for colon-targeted delivery of meloxicam (MLX) microsponges. Modified quassi-emulsion solvent diffusion method was used to formulate microsponges (MS), based on 3(2) full factorial design. The effects of volume of dichloromethane and EudragitRS100 content (independent variables) were determined on the particle size, entrapment efficiency and %cumulative drug release of MS1-MS9. The optimized formulation, MS5 (d(mean)=44.47 µm, %EE=98.73, %CDR=97.32 and followed zero order release) was developed into colon-targeted matrix tablet using calcium pectinate as the matrix. The optimized colon-targeted tablet (MS5T2) shielded MLX loaded microsponges in gastrointestinal region and selectively delivered them to colon, as vizualized by vivo fluoroscopy in rabbits. The pharmacokinetic evaluation of MS5T2 in rabbits, revealed appearance of drug appeared in plasma after a lag time of 7h; a t(max) of 30 h with Fr=61.047%, thus presenting a formulation suitable for targeted colonic delivery. CLSM studies provided an evidence for colonic luminal retentive ability of microsponges at the end of 8h upon oral administration of MS5T2. Thus calcium pectinate matrix tablet loaded with MLX microsponges was developed as a promising system for the colon-specific delivery that has potential for use as an adjuvant therapy for colorectal cancer.

Paw inflammation model in dogs for preclinical pharmacokinetic/pharmacodynamic investigations of nonsteroidal anti-inflammatory drugs.

The goal of the present study was to develop and validate a new canine model of inflammation. The motivation was to make available a scientifically appropriate and ethically acceptable model to conduct pharmacokinetic/pharmacodynamic investigations for testing nonsteroidal anti-inflammatory drugs in dogs. A kaolin-induce paw inflammation model previously developed in cats was adapted to the dog. The paw inflammation developed within a few hours, reached maximum values 24 h and up to 3 days after kaolin administration, and then progressively resolved over 2 months. Five end points of clinical interest (body temperature, creeping time under a tunnel, paw withdrawal latency to a standardized thermal stimulus, lameness score, and vertical force developed during walking on a force plate) were measured regularly over the next 24 h and beyond to characterize the time development of the inflammation either in control conditions (placebo period) or after the administration of meloxicam (test period) according to a crossover design. Pharmacodynamic data were modeled using an indirect response pharmacokinetic/pharmacodynamic model. This model described three effects of meloxicam, namely, classic anti-inflammatory, analgesic, and antipyretic effects. The mean plasma meloxicam IC(50) values were 210 ng/ml for the antipyretic effect, 390 ng/ml for the analgesic effect, and 546 ng/ml for the vertical force exerted by the paw on the ground as measured by force plates. These in vivo IC(50) values require approximately 80 (antipyretic effect) to 90% (all other effects) cyclooxygenase-2 inhibition as calculated ex vivo whole-blood assay data.

Effect of inflammation on kidney function and pharmacokinetics of COX-2 selective nonsteroidal anti-inflammatory drugs rofecoxib and meloxicam.

Chronic arthritis adversely affects glomerular function and nonsteroidal anti-inflammatory drugs (NSAIDs) reduce electrolyte urinary excretion. In addition, both acute and chronic inflammations may alter clearance of drugs. We studied (a) the effects of inflammation on the renal function and pharmacokinetics of rofecoxib and meloxicam; (b) whether inflammation could exacerbate reduced electrolytes excretion changes observed with NSAIDs; and (c) the influence of inflammation on distribution of these drugs into the kidney. Single oral doses of rofecoxib (10 mg kg(-1)), meloxicam (3 mg kg(-1)) or placebo were administered to normal or pre-adjuvant arthritic rats. Blood and urine samples were collected for the measurement of plasma nitrite, BUN and creatinine. The urinary excretion of sodium and potassium was also determined. Nitrite, BUN and plasma creatinine were increased starting on day 9 in the groups with inflammation. Sodium and potassium excretion rates were not affected by inflammation. Meloxicam did not alter the electrolyte excretion in any of the groups. Rofecoxib significantly decreased sodium and potassium excretion in normal rats and potassium excretion in inflamed rats. Inflammation significantly increased plasma concentrations of rofecoxib, but not meloxicam. The ratios of the kidney:plasma concentrations were not significantly altered by inflammation following either drug. Inflammation altered kidney function, demonstrated by increases in BUN and plasma creatinine. However, it did not influence the urinary electrolytes excretion. Since we have observed similar patterns of the effect of NSAIDs on kidney under healthy and inflammatory conditions, one may conclude that inflammation does not exacerbate the adverse effect.

Comparison of analgesic and anti-inflammatory activity of meloxicam gel with diclofenac and piroxicam gels in animal models: pharmacokinetic parameters after topical application.

Meloxicam, a non-steroidal anti-inflammatory drug, is a preferential inhibitor of cyclooxygenase-2 and has demonstrated potent analgesic and anti-inflammatory activity after oral administration. The present work was carried out to elucidate the anti-inflammatory and analgesic activity of a newer topical gel formulation of meloxicam (1% w/w gel) and compare it with 0.5% w/w piroxicam and 1% w/w diclofenac gels in experimental animal models. The study was also extended to determine the pharmacokinetic profile of a newer formulation of meloxicam gel after topical application on depilated skin of rats. The anti-inflammatory activities of meloxicam, piroxicam and diclofenac gels were compared using carrageenan-induced acute paw oedema and complete Freund's adjuvant-induced chronic paw oedema in rats. Meloxicam gel showed increased protection against inflammation as compared to piroxicam and diclofenac gels. Acetic acid-induced writhing and formalin-induced phase I and phase II pain models were used to compare their analgesic activity. Meloxicam gel showed significant protection in formalin-induced phase II pain whereas its analgesic activity was less as compared to diclofenac and piroxicam gels in writhing test and formalin-induced phase I pain. The pharmacokinetic studies showed peak plasma drug concentration (C(max)) of 48.48 +/- 6.57 microg/ml at 2 h (T(max)) after topical application of 500 mg of meloxicam gel formulation. The area under the curve as calculated from 0 to 6 h was found to be 114.18 +/- 4.23 and 194.13 +/- 3.78 microg x h/ml for 0 to infinity. The results indicate that topical preparation of meloxicam could be an effective alternative to diclofenac and piroxicam gels in inflammatory conditions and its associated pain with the possibility of less systemic side-effects.

Preclinical overview of brinzolamide.

The development of topically active carbonic anhydrase inhibitors (CAIs) is a significant recent achievement in glaucoma medical treatment. Brinzolamide, the newest topical CAI, exhibits selectivity, high affinity, and potent inhibitory activity for the carbonic anhydrase type II isozyme (CA-II), which is involved in aqueous humor secretion. These characteristics, along with good ocular bioavailability, make brinzolamide maximally effective in lowering intraocular pressure (IOP) by locally inhibiting CA-II in the ciliary processes and suppressing aqueous humor secretion. Notable among its attributes as a safe and efficacious glaucoma drug is brinzolamide's superior ocular comfort profile because of its optimized suspension formulation at physiologic pH. The degree of tolerability in the eye is considered an important determinant of a patient's willingness to comply with the dosing regimen for a long-term glaucoma medication. Results from the preclinical pharmacologic evaluation of brinzolamide indicated that it acts specifically to inhibit CA without significant other pharmacologic actions that could introduce undesired side effects. Moreover, the typical side effects associated with systemically administered CAIs are expected to occur at a lower incidence or not occur at all with brinzolamide, as its therapeutic dose and low systemic absorption do not produce a problematic level of systemic CA inhibition. Brinzolamide's long tissue half-life in the eye, particularly in the iris-ciliary body, favors a prolonged duration of IOP lowering. This was substantiated in clinical trials, which showed that twice-daily brinzolamide provides as significant an IOP reduction as three-times-daily brinzolamide or dorzolamide in a relatively high percentage of patients. Brinzolamide has been shown by the laser Doppler flowmetry technique to improve blood flow to the optic nerve head in pigmented rabbits after topical administration, without producing an increase of blood pCO2, indicating a potential for a local vasodilatory effect involving the optic nerve head circulation. The mean concentration of brinzolamide found in the retina of pigmented rabbits (0.338 microg equivalents/g) after a single dose of 14C-brinzolamide is sufficient to inhibit CA-II. These data suggest that topical brinzolamide could improve the blood flow in the optic nerve head in humans should it inhibit carbonic anhydrase in that vascular bed. Brinzolamide is a new topically active CAI that is safe and efficacious for reducing intraocular pressure. It offers the convenience of topical dose administration and greater freedom from side effects related to the inhibition of CA seen with the systemic administration of CAIs. Its formulation has been optimized to provide greater comfort upon instillation, and this can result in a higher compliance rate by the patient. Results of studies in animals show that brinzolamide has promise for increasing blood flow to the optic nerve head; however, this requires further assessment in the clinic. Brinzolamide represents a significant technical achievement and an important addition to the medical treatment of glaucoma as both a primary and an adjunctive drug.

Ampiroxicam, an anti-inflammatory agent which is a prodrug of piroxicam.

Ampiroxicam is a nonacidic ether carbonate prodrug of piroxicam. Our results demonstrate that, in contrast to piroxicam, ampiroxicam does not possess detectable prostaglandin synthesis inhibitory activity in vitro. Ampiroxicam, however, has similar in vivo potency to piroxicam in suppressing paw swelling in rat adjuvant arthritis. In an acute model of paw inflammation in rats, ampiroxicam is less potent than piroxicam itself: the ED50's of ampiroxicam are 9- and 3.5-fold higher than those of piroxicam following a single or multiple (5) daily oral doses, respectively. Using the phenylbenzoquinone stretching test as a method of evaluating acute analgetic activity, the ED50 for ampiroxicam is about 3-fold higher than that of piroxicam. These tests of activity share the property of being partially prostaglandin-dependent. Ampiroxicam itself is not observed in plasma after oral dosing to man, nor in the rat, dog, and monkey as reported here. Bioavailability studies show that conversion to piroxicam is about 100%, 90%, 70%, and 50% in these four species, respectively. These results indicate that ampiroxicam's anti-inflammatory activity is produced in vivo by conversion to piroxicam and support its credentials as an efficacious prodrug of piroxicam.

Distribution of [14C]meloxicam in joints of rats with adjuvant arthritis.

Using the new non-steroidal anti-inflammatory agent meloxicam (Mel), comparative investigations on pharmacokinetics and metabolism show good agreement between results in man and in the rat. To demonstrate preferential localization of the compound in inflamed sites, the distribution of the radiolabelled compound in arthritic joints of rats was studied using autoradiography. For that purpose an arthritis-inducing antigen was given to male albino rats. Twenty one days after antigen injection, all animals were given [14C]Mel orally. At three different times after receiving the labelled compound, the animals were sacrificed under anaesthesia. Tissue sections from each leg of each animal were taken for autoradiography. Sections were stained after film exposure using Masson-Goldner staining. The radiolabelled compound was preferentially localized in the areas which stained for inflamed connective tissue. The distribution pattern described persists beyond 24 h post-application. The figures indicate a highly efficient distribution of the radioactivity into chronically inflamed tissue of the hind foot-pads. Since negligible radioactivity was found in the front foot-pads, it is concluded that uptake into inflamed tissue is favoured.