影响盐酸维拉帕米脉冲释放片体外“时滞”的因素考察

目的：考察影响盐酸维拉帕米脉冲片控时效果的因素。方法：通过外溶出的方法考察脉冲控释片的时滞,主要包括溶出条件和处方因素两方面。结果：介质的酸碱度不影响制剂的控时效果;转速不影响制起崩时间,但对溶出速度有一定的影响;粘度越大的介质,释药时滞也越大。包衣用量增加、控时层中亲水性成分PEG6000含量减小、控时层中PEG类型的分子量的增加,均能使药物释放滞后时间明显增大;包衣颗粒大小对控时效果基本没有影响。结论：溶出条件作用因素的考察为进一步的体内研究奠定了基础;处方因素的考察为制剂的时滞调控和释药特征研究作了准备。     

Compatibility studies of nateglinide with excipients in immediate release tablets

Experiments were done to assess the compatibility of nateglinide with selected excipients in the development of immediate release tablets of nateglinide by thermal and isothermal stress testing (IST) techniques. To evaluate the drug-excipient compatibility, different techniques such as differential scanning calorimetric (DSC) study, infra-red (IR) spectrophotometric study and isothermal stress testing were adopted. The results of DSC study showed that magnesium stearate exhibited some interaction with nateglinide. However, the results of IR, and IST studies showed that all the excipients used in the formula were compatible with nateglinide. Optimized formulations developed using the compatible excipients were found to be stable over 3 months of accelerated stability studies (40 ± 2°C and 75 ± 5% RH). Overall, compatibility of excipients with nateglinide was successfully evaluated using a combination of thermal and IST methods and the formulations developed using the compatible excipients were found to be stable.     

Once-daily controlled release remoxipride is equieffective with twice-daily immediate release remoxipride in the treatment of schizophrenia

A controlled release (CR) formulation of remoxipride (Roxiam(?), Astra) given once-daily was compared to immediate release (IR) remoxipride given twice-daily, with respect to efficacy and tolerability, in a 4-week multicentre parallel-group dose titration (200-600 mg/day) study with acutely ill schizophrenic patients. Forty- three patients received remoxipride CR (mean dose 344 mg/day) and 49 patients received remoxipride IR (mean dose 346 mg/day). Efficacy was assessed using the Kolakowska version of the Brief Psychiatric Rating Scale (BPRS score of ≥ 18 points at entry) and the Clinical Global Impression scale (CGI), while extrapyramidal symptoms were rated using the Simpson and Angus scale. Both formulations of remoxipride produced clinical improvement, with the BPRS median total score falling from 35 at baseline to 16 at last rating in the remoxipride CR group, and from 33 to 12.5 in the remoxipride IR group. More than 70% of the patients in both groups were assessed as 'much improved' or 'very much improved' according to the CGI scale. Both formulations of remoxipride were well-tolerated, with a low incidence of treatment-emergent adverse symptoms, including extrapyramidal side effects. No statistically significant differences were detected between the treatment groups with regard to efficacy, safety or tolerability.     

Steady-state pharmacokinetics of controlled release and immediate release formulations of remoxipride in patients with chronic schizophrenia

Twenty-four stable, chronic schizophrenic inpatients were entered in a double-blind crossover study designed to compare single dose and steady state pharmacokinetic profiles of an immediate release formulation (IR) 200 mg BID and a controlled release formulation (CR) of remoxipride 400 mg once daily. The rate of absorption of remoxipride CR was significantly lower than the IR formulation andt _max was prolonged from 1.3 to 7.9 h after a single dose and from 2.2 to 6.0 h after repeated dosing. Although the single dose of remoxipride CR was twice as large as the single dose of the IR, theC _max was similar for both formulations after a single dose. However, theC _max at steady state was slightly lower for CR. There was significantly less fluctuation in plasma concentrations at steady state with the CR formulation, although the average plasma concentration of remoxipride IR and CR was similar. The mean relative bioavailability with regard to the amount of remoxipride absorbed after remoxipride CR 400 mg once daily compared to IR 200 mg BID was 97%. It was concluded that the CR formulation is suitable for a once-daily administration from a pharmacokinetic point of view.     

IVIVC in oral absorption for fenofibrate immediate release tablets using a dissolution/permeation system

The usefulness of a dissolution/permeation (D/P) system to predict the in vivo performance of solid dosage forms containing the poorly soluble drug, fenofibrate, was studied. Biorelevant dissolution media simulating the fasted and fed state conditions of the human gastrointestinal tract were used in order to simulate the effect of food on the absorption of fenofibrate. Moreover, the results obtained from the D/P system were correlated with pharmacokinetic parameters obtained following in vivo studies in rats. The in vitro parameter (amount permeated in the D/P system) reflected well the in vivo performance in rats in terms of AUC and C(max) of fenofibric acid. This study thus demonstrates the potential of the D/P system as valuable tool for absorption screening of dosage forms for poorly soluble drugs.     

Evaluation of the feasibility of switching from immediate release quetiapine to extended release quetiapine fumarate in stable outpatients with schizophrenia

This double-blind, double-dummy study (D1444C00146) evaluated the efficacy and safety of switching patients with clinically stable schizophrenia from quetiapine immediate release (IR) to the same dose of once-daily extended release quetiapine fumarate (quetiapine XR). Patients received quetiapine IR 400-800 mg/day twice daily for 4 weeks, and were then randomized (2 : 1) to a once-daily equivalent dose of quetiapine XR or maintained on IR for 6 weeks. The primary variable was the proportion of patients who discontinued treatment owing to lack of efficacy or whose Positive and Negative Syndrome Scale scores increased by at least 20% from randomization to any visit. In total, 497 patients were randomized to quetiapine XR (n=331) or IR (n=166). Noninferiority (6% margin; one-sided test, 2.5% significance level) was narrowly missed for the primary efficacy variable for the modified intention-to-treat population (9.1%, quetiapine XR; 7.2%, quetiapine IR; difference 1.86%; 95% confidence interval: -3.78, 6.57; P=0.0431), but was shown for the per-protocol population (5.3%, quetiapine XR; 6.2%, quetiapine IR; difference: -0.83%; 95% confidence interval: -6.75, 3.71; P=0.0017). Serious adverse event incidence was low for quetiapine XR and IR; there were no unexpected adverse events. In conclusion, efficacy was maintained without compromising safety/tolerability when switching patients with stable schizophrenia from twice-daily quetiapine IR to once-daily quetiapine XR (400-800 mg/day).     

Concentration-effect relationship of levodopa in patients with Parkinson's disease after oral administration of an immediate release and a controlled release formulation.

1. The relationship between plasma concentration of levodopa and motor-response was investigated in 12 patients with Parkinson's disease who showed marked response fluctuations, after a single oral dose of an immediate release (IR) formulation (100 mg levodopa/25 mg genserazide) and a controlled release (CR) formulation (300 mg levodopa/75 mg benserazide), using a double-blind, randomized, cross-over design. 2. The sum score of the Columbia University Rating Scale (CURS sigma) was used for pharmacodynamic assessment. A sigmoidal Emax-model was fitted to the data using a semiparametric pharmacokinetic/dynamic approach. 3. The dose-corrected AUC of levodopa after the IR-formulation was 27.5 (+/- 9.1 s.d.) ng ml-1 h per mg and 23.2 (+/- 4.6 s.d.) ng ml-1 h per mg after the CR-formulation. Cmax was 1714 (+/- 1027 s.d.) ng ml-1 after the IR-formulation and 1494 (+/- 383 s.d.) ng ml-1 after the CR-formulation. 4. With both preparations, the maximal response to levodopa (Emax) was a decrease in the CURS sigma rating of about 27 scores. Estimates of the EC50 of levodopa were 495 (+/- 144 s.d.) ng ml-1 (IR) and 1024 (+/- 502 s.d.) ng ml-1 (CR), respectively (95%-CI: 1.51-2.66, point estimator 1.95). The mean duration of the motor response was 1.9 (+/- 0.5 s.d.) h (IR) and 2.8 (+/- 0.7 s.d.) h (CR), respectively (95%-CI: 1.12-2.04, point estimator 1.53).(ABSTRACT TRUNCATED AT 250 WORDS)     

Food-dependent disintegration of immediate release fosamprenavir tablets: In vitro evaluation using magnetic resonance imaging and a dynamic gastrointestinal system

In the present study, we demonstrated the value of two advanced tools, the TNO gastric and small Intestinal Model (TIM-1) and magnetic resonance imaging (MRI), for the in vitro evaluation of food-dependent disintegration of immediate release fosamprenavir tablets. Upon introduction of a tablet with the nutritional drink Scandishake Mix® in the stomach compartment of TIM-1, simulating the fed state, disintegration and fosamprenavir dissolution were significantly postponed compared to the fasted state (lag time 80 ± 23 min). This resulted in a lag in the appearance of bioaccessible fosamprenavir (<5% during the first 2 h), even though the nutritional state did not significantly alter the cumulative bioaccessibility after 5 h. These results were in agreement with the previously observed postprandial delay in gastric fosamprenavir tablet disintegration and subsequent amprenavir absorption in healthy volunteers. Therefore, TIM-1 can be used in tablet development to identify food-induced disintegration issues causing unexpected clinical behavior. From a mechanistic perspective, we applied MRI to illustrate impaired water ingress in fosamprenavir tablets immersed in the nutritional drink compared to simulated gastric fluid. This effect may be attributed to both competition between nutritional components and the tablet for the available water (indicated by reduced rotational and translational diffusion) as well as the possible formation of a food-dependent precipitation layer on the HPMC-coated tablet.     

A compartment model for percutaneous absorption: compatibility of lag time and steady-state flux with diffusion model.

The lag times and steady-state flux predicted by a specific case of the compartment model, which was recently proposed to generate finite-dose percutaneous permeation pharmacokinetics, are compared with those predicted by the diffusion model. When the intercompartmental transfer rate constants are defined so that the three statistical moments of the compartmental model (the mean residence times of a drug in the vehicle and that in the skin and the variance of residence time in the vehicle) are identical to those in the diffusion model, the lag times and steady-state flux values predicted by the two models are the same.     

Bioavailability of triple-bead mixed amphetamine salts compared with a dose-augmentation strategy of mixed amphetamine salts extended release plus mixed amphetamine salts immediate release*

ABSTRACT

Objective: To compare the single-dose pharmacokinetics of triple-bead mixed amphetamine salts (MAS), an oral, once-daily, enhanced extended-release amphetamine formulation, with MAS extended release (MAS XR) (Adderall XR^?) + MAS immediate release (MAS IR) administered 8?h later.

Methods: This was a phase I, randomized, open-label, single-dose, single-center, two-period, crossover study in healthy adult volunteers designed to evaluate the bioavailability of triple-bead MAS over the course of a full day. Subjects were randomized to triple-bead MAS 37.5?mg or MAS XR 25?mg + MAS IR 12.5?mg admin­istered 8?h later (MAS XR + MAS IR). The reference treatment was designed to mimic the clinical practice of providing extended coverage by supplementing a morning dose of MAS XR with a dose of MAS IR 8?h later in order to increase the duration of action. Plasma was assayed for d?amphetamine and l?amphetamine. Treatment-emergent adverse events (TEAEs), vital signs, electrocardiograms (ECGs), and laboratory data were also collected for safety evaluation.

Results: Exposure to d? and l?amphetamine was equivalent between triple-bead MAS and MAS XR + MAS IR based on maximum plasma concentration (C_max) and area under the plasma concentration–time curve from time 0 to infinity (AUC_0–∞). For C_max, least-squares mean ratios comparing triple-bead MAS with MAS XR + MAS IR were 101.0% and 90.9% for d?amphetamine and l?amphetamine, respectively, and for AUC_0–∞ were 104.4% and 95.3% for d?amphetamine and l?amphetamine, respectively. Median time to maximum observed plasma concentration (T_max) values for d?amphetamine and l?amphetamine were 8.0?h for triple-bead MAS and 10.0?h for MAS XR + MAS IR. There were no clinically meaningful differences between the study formulations for TEAEs or laboratory values. One subject experienced an ECG abnormality (asymptomatic premature ventricular contractions) leading to early termination from the study.

Conclusions: In healthy adults, the exposure observed with triple-bead MAS 37.5?mg was bioequivalent to MAS XR 25?mg supplemented by MAS IR 12.5?mg administered 8?h later. These data demonstrate that a single morning dose of triple-bead MAS provides equivalent plasma concentrations to those observed with a dose-augmentation strategy of MAS XR in the morning followed by MAS IR in the afternoon, while minimizing peak-to-trough fluctuations. Triple-bead MAS was also generally well-tolerated in this study.     

Association between time to progression and subsequent survival inceritinib-treated patients with advanced ALK-positive non-small-cell lung cancer

Objective: Time to progression (TTP) is a surrogate marker of overall survival (OS). However, OS is also dependent on post-progression survival (PPS). This study evaluated the association between TTP and the duration of PPS among adult patients who received ceritinib (Zykadia¹) for the treatment of advanced anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC).

Research design and methods: A pooled analysis was performed on 181 ASCEND-1 (phase I) and ASCEND-2 (phase II) patients who experienced disease progression while on ceritinib. TTP was assessed on its association with PPS in a Kaplan–Meier analysis and in Cox proportional hazard models, adjusted for clinical covariates.

Main outcome measures: Main outcomes measured include TTP, PPS, and OS.

Results: Patients with TTP ≥6 months experienced significantly longer PPS compared to those with TTP <6 months (median: 9.8 vs. 6.5 months, log-rank p-value <?.01). When TTP was assessed as a continuous variable, every 3 months of longer TTP was associated with a 21% lower hazard of death following progression (hazard ratio [HR]: 0.79, 95% confidence interval [CI]: 0.63–1.00; adjusted HR: 0.79, 95% CI: 0.64–0.99). This positive association translated into an OS benefit: each 3 months of longer TTP was associated with a lower hazard of death (adjusted HR: 0.46, 95% CI: 0.37–0.58). Median OS was 20.0 months for patients with TTP ≥6 months and was 10.9 months for patients with TTP <6 months.

Conclusions: A longer duration of TTP after treatment with ceritinib was significantly associated with a longer duration of both PPS and OS.     

A novel thermo-responsive drug delivery system with positive controlled release

The model drug, 5-fluorouracil (5-FU) was loaded into the poly(N-isopropylacrylamide) (PNIPA) hydrogel at 25 degrees C, then the drug-loaded, swollen hydrogel sample was carefully enveloped in the dialysis bag to form a novel thermo-responsive drug delivery system (DDS). The concentration of released 5-FU was monitored at 266 nm on the UV spectrophotometer. We found that this novel DDS provides a positive drug release pattern and the drug, 5-FU, was released faster at the increased temperature (37 degrees C, >25 degrees C) than the one at the decreased temperature (10 degrees C, <25 degrees C). This was attributed to the double control of the thermo-sensitivity of the hydrogel matrix and the dialysis membrane. By employing the fast response PNIPA hydrogel instead of the conventional hydrogel in this novel DDS, we can further control the drug release rate and/or drug release amount etc., without changing the positive, thermo-responsive drug release pattern.     

In vitro/in vivo correlations of dissolution data of carbamazepine immediate release tablets with pharmacokinetic data obtained in healthy volunteers.

The aim of the study was to select a dissolution test method for carbamazepine (CBZ) immediate release tablets, giving the best in vitro/in vivo correlations (IVIVC) and to determine the potential of this method as an estimate for bioequivalence testing. Four 200 mg CBZ products which are sold on the Dutch market, covering the innovator and three generic products, were selected. They had been tested in a randomised, fourway cross-over bioavailability study in healthy volunteers. Their dissolution rate behaviour in vitro was investigated in two dissolution media: (1) 1% sodium lauryl sulphate in water (SLS), in accordance with the United States Pharmacopeia (USP); (2) 0.1 mol/l Hydrochloric acid in water (HC). In the bioavailability study these products had shown no large differences in the extent of absorption (AUC(0-infinity);) but large differences in absorption rate. The products now also showed large differences in dissolution rate in vitro in both dissolution media, the rank order being the same as for the absorption rate. It was concluded that the absorption rate in vivo depends on the dissolution rate in vivo. 'Level C' IVIVC according to the USP were optimised by plotting percentages dissolved on selected time points (D values) or their reciprocals (1/D values), against several pharmacokinetic parameters primarily related to the absorption phase and against AUC(0-infinity). In this way for each IVIVC the optimum D or 1/D value, was calculated. For both media no meaningful IVIVC were obtained with AUC(0-infinity), but favourable IVIVC were obtained with the parameters primarily related to the absorption phase. In the bioavailability study indicated above it was found that, among the pharmacokinetic characteristics primarily related to the absorption phase, C(max) is the most promising in expressing rate of absorption in bioequivalence testing in single dose studies with CBZ immediate release tablets. Consequently, C(max) was selected for expressing rate of absorption. The most favourable IVIVC were obtained with D(20) in SLS versus C(max). From this IVIVC and the requirements for bioequivalence (AUC(0-infinity): 0.8-1.25 and C(max) : 0.75-1.35; 90% confidence interval), a specification for dissolution testing in SLS was calculated as follows: 'after 20 minutes, 34-99% dissolved'. Owing to the fact that the rate of absorption in vivo depends on i.a. the dissolution rate in vivo, it can be concluded that with this specification bioequivalence with respect to both rate of absorption and extent of absorption is ensured. As this specification is comparable with the USP specification: 'not less than 75% dissolved after 1 h', it is concluded that the USP specification is suitable to ensure bioequivalence of CBZ immediate release tablets.     

A selective effect of protein kinase C activators on noradrenaline release compared with subsequent contraction in canine isolated saphenous veins.

1. Effects of protein kinase C (PKC) activators and inhibitors on both tritium overflow and subsequent contraction evoked by transmural nerve stimulation (TNS) were investigated in canine saphenous veins prelabelled with [3H]-noradrenaline. 2. Activation of PKC by stepwise increasing concentrations (0.01 nM-1 microM) of 12-O-tetradecanoylphorbol 13-acetate (TPA), phorbol 12,13-dibutyrate (PDBu) or mezerein caused a significant and concentration-dependent enhancement of the tritium overflow evoked by TNS, while the activators failed to affect the corresponding contraction except with the highest concentration of PDBu when the contraction was significantly reduced. Phorbol, which is inactive on PKC, had no effects on the tritium overflow and contraction induced by TNS. 3. PKC inhibitors, polymyxin B (1 and 10 microM) and the isoquinolinesulphonamide, H-7 (1 microM), inhibited significantly the phorbol ester-potentiated tritium overflow evoked by TNS with no effects on the contraction. H-7 and the related inhibitor H-8 at 10 microM reduced significantly both responses to TNS in the presence of TPA, while they suppressed only the TNS-induced contraction in the absence of TPA. 4. None of the PKC activators or inhibitors affected the spontaneous tritium overflow. 5. PDBu (0.01 and 0.1 microM) elevated resting tension of the veins more effectively than TPA and mezerein. 6. These results suggest that PKC may modulate electrically stimulated noradrenaline release from adrenergic nerve endings of the canine saphenous veins and the PKC activators may act more selectively on presynaptic than postsynaptic sites, but have no apparent effect on postjunctional noradrenergic mechanisms.     

Biowaiver monographs for immediate release solid oral dosage forms based on biopharmaceutics classification system (BCS) literature data: verapamil hydrochloride, propranolol hydrochloride, and atenolol

Literature data related to the Biopharmaceutics Classification System (BCS) are presented on verapamil hydrochloride, propranolol hydrochloride, and atenolol in the form of BCS-monographs. Data on the qualitative composition of immediate release (IR) tablets containing these active substances with a Marketing Authorization (MA) in the Netherlands (NL) are also provided; in view of these MA's the assumption was made that these tablets were bioequivalent to the innovator product. The development of a database with BCS-related data is announced by the International Pharmaceutical Federation (FIP).     

Design and evaluation of a dry coated drug delivery system with floating-pulsatile release

The objective of this work was to develop and evaluate a floating-pulsatile drug delivery system intended for chronopharmacotherapy. Floating-pulsatile concept was applied to increase the gastric residence of the dosage form having lag phase followed by a burst release. To overcome limitations of various approaches for imparting buoyancy, we generated the system which consisted of three different parts, a core tablet, containing the active ingredient, an erodible outer shell and a top cover buoyant layer. The dry coated tablet consists in a drug-containing core, coated by a hydrophilic erodible polymer which is responsible for a lag phase in the onset of pulsatile release. The buoyant layer, prepared with Methocel K4M, Carbopol 934P and sodium bicarbonate, provides buoyancy to increase the retention of the oral dosage form in the stomach. The effect of the hydrophilic erodible polymer characteristics on the lag time and drug release was investigated. Developed formulations were evaluated for their buoyancy, dissolution and pharmacokinetic, as well gamma-scintigraphically. The results showed that a certain lag time before the drug released generally due to the erosion of the dry coated layer. Floating time was controlled by the quantity and composition of the buoyant layer. Both pharmacokinetic and gamma-scintigraphic data point out the capability of the system of prolonged residence of the tablets in the stomach and releasing drugs after a programmed lag time.     

Histamine release by free radicals: the relationship with the signal transduction system

In isolated rat serosal mast cells exposed to free radical-generating systems, the release of histamine was associated with a significant increase in malonyldialdehyde (MDA) production suggesting a relationship between histamine release and membrane lipid peroxidation. Under these circumstances, an increase in cytosolic calcium was observed, uncoupled with any stimulation of inositol phospholipid (PtdIns) breakdown. The data suggest similarities between the release of histamine induced by calcium ionophores and by free radical-generating systems.     

To reduce premature drug release while ensuring burst intracellular drug release of solid lipid nanoparticle-based drug delivery system with clathrin modification

Nanoscale drug delivery system (NDDS) with slow premature drug release (PDR) while ensuring burst intracellular drug release (BIDR) is becoming a hot point in NDDS-based nanomedicine. Here we used clathrin to modify a solid lipid nanoparticle (SLN)-based NDDS of salinomycin (SLN-SAL) to prepare NDDS with reduced PDR while ensuring BIDR. Drug-release-kinetic experiments revealed that clathrin modified SLN-SAL (CMSLN-SAL) reduced PDR while ensured BIDR of its prototype NDDS, SLN-SAL. Mechanism experiments revealed that clathrin modification reduced PDR of SLN-SAL through increasing the mechanical strength of SLN-SAL and ensured BIDR of SLN-SAL through lipid membrane fusion after its clathrin shell was de-polymerized by a cytoplasm enzyme, HSC70. In addition, CMSLN-SAL had significantly higher intracellular uptake and stronger inhibitive effects on cancer cells than that of SLN-SAL. These results demonstrated that clathrin modification is an effective way to reduce PDR while ensuring BIDR and increasing the anticancer effects of SLN-based NDDS.