In vivo evaluation of a theophylline oral controlled-release unit dosage form

A 200 mg controlled-release unit dosage form which was designed and developed showed desired in vitro release characteristics. This dosage form was subjected to in vivo studies (single and multiple p.o. dosing) in Beagle dogs with the aim of insuring the desired controlled-release performance in a biologic system. Using a parallel study design (intravenous, p.o. solution, p.o. controlled-release standard and p.o. controlled-release test dosage form), the dosage form index (DI), the fraction of drug absorbed (absolute bioavailability) (f) and the extent of (relative) bioavailability (EBA) of the experimental dosage form were determined.     

In vivo evaluation of xanthan gum as a potential excipient for oral controlled-release matrix tablet formulation

The controlled-release (CR) properties of xanthan gum (XG) matrix tablets were investigated in vivo. Indomethacin and the sodium salt of indomethacin were selected as model drugs to examine the properties of formulations of a very poorly soluble and a highly soluble drug, respectively. The performance of XG matrices was compared with a marketed CR product containing an equivalent dose of indomethacin. A single oral dose pharmacokinetic study was conducted according to a randomised crossover design in six healthy male volunteers with three dosage forms: (A), 50 mg indomethacin tablets; and (B), 50 mg sodium indomethacin tablets both prepared with XG; and (C) Flexin® tablets. Dosage forms A and C showed the same in vitro release profile, while dosage form B demonstrated a faster release of the drug. There was no statistically significant difference in the time to reach the maximal plasma concentration between dosage form A and B or the reference product. Whereas the maximal plasma concentrations were varied considerably and found to be 1.73, 1.07, and 0.73 μg/ml for the dosage form A, B, and C, respectively. No statistically significant difference in AUC_0–32 was found between either of the two test products and the reference product, but three way analysis of variance indicated an influence of the variable ‘volunteers’ on this parameter, indicating that interpretation of these data must be done with great caution. Based on these findings, the three products can be considered as bioequivalent. However, it seems that the drug released from the test products reached the minimum effective concentration earlier and remained longer within the therapeutic range. Based on these findings, it can be concluded that, although the common pharmacokinetic parameters of the drug from the test products are not significantly different from those of the marketed product, the therapeutic efficacy of the drug from the former may be superior to that of the latter.     

Calculation of the antibiotic level in the lung tissue and bronchial secretion with an oral controlled-release dosage form

The drug level-time history in plasma and lung tissue was calculated with an antibiotic orally delivered in either an immediate-release or a controlled-release dosage form. The drug profiles were compared with experiment results given in the literature. In the same way, the drug level was evaluated in the bronchial secretion in contact with lung tissue. A numerical model, based on finite differences taking all the known facts into account was built and tested with the data found in the literature. Transport of the drug was looked at, including a stage of diffusion through the thickness of the lung tissue and a stage of convection into the bronchial secretion. A few parameters were thus considered, including the thickness of the lung tissue and the diffusivity of the antiobiotic through the tissue, the thickness of the bronchial secretion and the coefficient of convective transport into the sputum which characterizes its viscosity. Two partition factors were also introduced for the drug: between the tissue and the serum and between the lung tissue and the bronchial secretion.     

Evaluation of an ibuprofen controlled-release tablet and placebo in postoperative oral surgery pain

Seventy-four outpatients with postoperative pain after oral surgery were randomly assigned, on a double-blind basis, to receive a single oral dose of a controlled-release tablet (CRT) containing 600 mg ibuprofen, two 600-mg ibuprofen CRTs, or placebo. Using a self-rating record, subjects rated their pain and its relief hourly for 12 hours after medicating. Estimates of total and peak analgesia were derived from these subjective reports. The ibuprofen CRTs (600 and 1200 mg) had manifested an analgesic effect by hour 1 and their efficacy persisted for 12 hours. Comparable effect for the two ibuprofen CRT dosages could suggest a plateau in analgesia at the 600-mg level or a lack of upside assay sensitivity. Duration of effect was longer for the CRTs than we have previously observed with conventional ibuprofen tablets. Adverse effects were transitory and consistent with the known pharmacologic profile of the medication evaluated.     

Research and development of oral controlled-release dosage forms

Important data concerning the gastrointestinal transit of oral solid dosage forms have been obtained recently by using the technique of gamma scintigraphy. It is now possible to put forward the principal limitations of the oral sustained release dosage forms actually available. The research and development of new controlled release products such as buoyant dosage forms and coevaporates with polymers should permit to decrease the large inter and intrasubject variations of drug plasma levels observed when the actual sustained release dosage forms are administered.     

Development of an aerosol dosage form containing insulin.

An aerosol dosage form containing insulin was developed by suspending insulin zinc crystals in fluorocarbon propellant and using oleyl alcohol to improve the insulin suspension and to prevent valve clogging. A metered valve was used to control the amount of insulin delivered per actuation. The dose dispensed, sedimentation rate, and particle-size distribution of the aerosol formulation were evaluated. The potency of the insulin delivered from the aerosol containers stored at various temperatures and time intervals was determined using a radioimmunoassay. Based upon preliminary stability data, which were treated kinetically, it was noted that insulin aerosols stored in a refrigerator at 7 degrees would have a predicted shelflife of approximately 19 years, whereas samples stored at 25 and 37 degrees would have shelflives of 11 and 2 months, respectively. Long-term stability studies are indicated to establish this conclusion. On the basis of this study, it was concluded that an insulin-containing aerosol dosage form can be formulated and that a suitable dose of insulin can be dispensed using commercially available metered dose valves. The actual dose of insulin dispensed would have to be related to the degree of absorption of insulin one would normally expect when insulin is administered by the inhalation route.     

Development and in vivo evaluation of a new oral nanoparticulate dosage form for leuprolide based on polyacrylic acid

It was the aim of this study to develop a nanoparticulate oral drug delivery system for leuprolide based on polyacrylic acid (PAA). In order to achieve formation of nanoparticles in a mild, aqueous environment, two different techniques were combined, namely hydrophobic ion pairing between leuprolide and sodium dodecyl sulphate in a first step, followed by encapsulation into nanoparticles gained by interpolymer complexation between polyacrylic acid and Pluronic F68. The obtained nanoparticles were characterized regarding particle size distribution, drug encapsulation efficiency and in vitro release profile. Additionally, the pharmacokinetic profiles of leuprolide after oral administration of PAA-nanoparticulate and PAA-control tablets to male Sprague-Dawley rats were assessed and compared. It could be shown, that hydrophobic ion pairing increased encapsulation efficacy of leuprolide and leads to a slowed drug release of nanoparticulate suspensions. Relative oral bioavailability of leuprolide could be increased by nanoparticulate tablets up to 4.2-fold. Results verify that the suggested approach is a promising strategy for the design of oral delivery systems for oral administration of peptide drugs.     

Development and in vivo evaluation of a new oral nanoparticulate dosage form for leuprolide based on polyacrylic acid

It was the aim of this study to develop a nanoparticulate oral drug delivery system for leuprolide based on polyacrylic acid (PAA). In order to achieve formation of nanoparticles in a mild, aqueous environment, two different techniques were combined, namely hydrophobic ion pairing between leuprolide and sodium dodecyl sulphate in a first step, followed by encapsulation into nanoparticles gained by interpolymer complexation between polyacrylic acid and Pluronic F68. The obtained nanoparticles were characterized regarding particle size distribution, drug encapsulation efficiency and in vitro release profile. Additionally, the pharmacokinetic profiles of leuprolide after oral administration of PAA-nanoparticulate and PAA-control tablets to male Sprague-Dawley rats were assessed and compared. It could be shown, that hydrophobic ion pairing increased encapsulation efficacy of leuprolide and leads to a slowed drug release of nanoparticulate suspensions. Relative oral bioavailability of leuprolide could be increased by nanoparticulate tablets up to 4.2-fold. Results verify that the suggested approach is a promising strategy for the design of oral delivery systems for oral administration of peptide drugs.     

Once-a-day controlled-release dosage form of divalproex sodium I: formulation design and in vitro/in vivo investigations

Divalproex sodium is a narrow therapeutic index drug that is widely used for the treatment of epilepsy, the manic episodes associated with bipolar disorder, and prophylaxis of migraine headaches. The present investigation was undertaken to design an oral dosage form that would provide once-daily administration with improved therapy and to explore the relationships between in vitro drug release and in vivo absorption. Controlled release hydrophilic matrix formulations of divalproex sodium were designed and evaluated via in vitro and in vivo studies. The release rate of divalproex sodium was modulated by varying different rate-controlling hydrophilic polymers and measured in vitro using a USP apparatus II dissolution method. Formulations with differing release rates were studied in beagle dogs and in healthy subjects. A selected formulation given once-daily was further evaluated against the commercial enteric tablet dosed twice-daily in a multiple dose study, and shown to provide desired nearly constant therapeutic plasma concentrations over the entire 24-h dosing interval. Preliminary linear relationships between in vitro dissolution and in vivo absorption were observed in both the animal model and in humans. However, the relationships were formulation dependent, indicating a need for further studies.     

奥沙西罗包衣控释片的制备及其质量评价

目的制备奥沙西罗包衣控释片,考察处方组成和工艺因素对制剂质量及体外释药行为的影响,并分析其释药机制。方法以乙基纤维素(EC-45cP)为骨架材料、乙基纤维素(EC-10cP)为成膜材料、聚乙二醇6000(PEG6000)为增塑剂,采用滚转包衣锅包衣,药物作为致孔剂控制药物释放,考察处方因素,片芯制备和包衣工艺等对制剂质量及体外释放行为的影响。结果片芯骨架材料用量、致孔剂用量、增塑剂用量、包衣厚度等因素对药物释放有明显影响。制剂体外释药行为符合零级动力学方程。结论薄膜包衣法制得奥沙西罗控释片,调整处方组成可获得12 h平稳释药的制剂。     

In vivo efficacy of a novel double liposome as an oral dosage form of salmon calcitonin

A simple method for the preparation of the inner liposomes for double liposomes (DL) was developed. The encapsulation efficiency of erythrosine in liposomes prepared by this new method is superior to that of the previous method because of the concentration of the drug in the lipid membrane. To evaluate the usefulness of DL prepared by the glass‐filter method modified in this study as an oral dosage form of salmon calcitonin (SCT), a suspension of liposomes containing SCT was administered to rats at a dose of 10 μg SCT/kg. Each type of DL showed better efficacy than its inner liposomes alone. The decrease in plasma calcium level was dependent on the electrical charge and particle size of the inner liposomes. The hypocalcemic efficacy of DL encapsulating SCT‐loading cationic liposomes relative to that after subcutaneous administration of SCT at a dose of 1 μg/kg was 6.47%, which was the largest value obtained. These results indicated that not only the particle size but also the electrical charge of inner liposomes affect intestinal absorption. This study verified that the efficacy was increased because of the decrease in diameter of the inner liposomes and the use of lipid with a positive charge. These findings concluded that DL might be useful as an oral dosage form of SCT. Drug Dev. Res. 58:253–257, 2003. © 2003 Wiley‐Liss, Inc.     

Extrusion and spheronization in the development of oral controlled-release dosage forms

The concept of multiparticulate dosage forms was introduced in the 1950s. With the increasing use of multiparticulate controlled release (CR) oral dosage forms, in recent times there has been a rise in interest in the methods of preparing these dosage forms. A method that has gained increased usage over the past few years is that of extrusion and spheronization. It has been extensively explored as a potential technique and also as a future method of choice for preparation of multiparticulate CR dosage forms. In this review an attempt is made to outline the general process of extrusion and spheronization and to assess its importance in the development of multiparticulate CR oral dosage forms.     

Once-daily propranolol extended-release tablet dosage form: formulation design and in vitro/in vivo investigation.

The purpose of this study was to develop and optimize the propranolol once-daily extended release formulations containing HPMC, Microcrystalline cellulose (MCC) and lactose. In vitro studies, the response surface methodology and multiple response optimization utilizing the polynomial equation were used to search for the optimal formulation with specific release rate at different time intervals. The constrained mixture experimental design was used to prepare systematic model formulations, which were composed of three formulation variables: the content of HPMC (X(1)) MCC (X(2)) and lactose (X(3)). The drug release percent at 1.5, 4, 8, 14 and 24 h were the target responses and were restricted to 15-30, 35-55, 55-75, 75-90 and 90-110%, respectively. The results showed that the optimized formulation provided a dissolution pattern equivalent to the predicted curve, which indicated that the optimal formulation could be obtained using response surface methodology. The mechanism of drug release from HMPC matrix tablets followed non-Fickian diffusion. In the vivo study, the MRT was prolonged for matrix tablets when compared with commercial immediate release tablets. Furthermore, a linear relationship between in vitro dissolution and in vivo absorption was observed in the beagle dogs.     

Biopharmaceutical evaluation of a tablet dosage form made from ethyl cellulose encapsulated aspirin particles

Ethyl cellulose encapsulated aspirin particles, suitable for preparation of direct compression tablets were prepared by the solvent evaporation method. Ethyl acetate was used as a solvent for the polymer in combination with a saturated solution of aspirin as the dispersing medium to prevent partitioning and drug loss. This resulted in a high yield of free-flowing, non-aggregated particles. In vitro-in vivo evaluations of the experimental aspirin tablets (made by direct compression of ethyl cellulose encapsulated particles) and three different commercial aspirin products (a conventional tablet, a timed-release tablet, and a timed-release caplet) were undertaken. Comparison of the dissolution in acidic media at pH 1.2 showed different release profiles for these products. While the conventional tablet and the timed-release caplet showed the highest and the lowest rate of release, respectively; the timed-release tablet and the experimentally made tablet revealed an intermediate rate and very similar release profiles. The cumulative urinary excretion data collected in a complete crossover study, using five healthy subjects further indicated that the experimental tablet has an in vivo availability identical to that of the timed-release tablet.     

Development of oral controlled-release tablet formulations based on diltiazem-carrageenan complex

Diltiazem HCl and lambda carrageenan react in distilled water to give a slightly soluble interaction product. The aim of this work was to verify the possible employment of lambda carrageenan-diltiazem (DTZ) complex in controlled-release formulations. The influence of complex particle size, compression force, pH of the dissolution medium, and tablet dimensions on drug release has been evaluated. The results confirm the suitability of the DTZ-carrageenan interaction product for controlled-release formulations. Good compaction properties allow tablets to slowly erode, with only the addition of the amount of hydroxypropyl methylcellulose (HPMC) necessary as a binding agent. The use of the finest sieve fraction results in the highest crushing strength values and in the slowest release rate, both in pH 1.2 and in pH 6.8. The force of compression does not affect the drug release for values over 16 kN. The release rate increases when the geometry of the tablet is varied so the surface/ volume ratio of the tablet is increased, suggesting a release mechanism involving surface dissolution/erosion.     

Stability-indicative HPLC determination of donepezil hydrochloride in tablet dosage form

Asimple, selective, precise and stability-indicative high-performance liquid chromatography (HPLC) method of analysis of donepezil hydrochloride in tablet dosage form has been developed and validated. The drug undergoes degradation under acidic, basic, peroxide, photochemical and thermal conditions. The method has been statistically validated for linearity, accuracy, precision, limit of detection, limit of quantitation, solution stability, and selectivity according to ICH recommendations. Due to its simplicity and accuracy, the method can be used for routine drug quality control.     

Formulation of an oral solid dosage form containing human interferon-alpha

The main objective of this study was to process the human alpha-interferon for the solid dosage form. The first step was the preparation of the intermediate product for the tablet making. Fluid bed apparatus with top spray method was applied for the layering of powdered cellulose with human alpha-interferon solutions. The intermediate product was compressed into tablet and an enteric solvent coating of the tablets was made in a fluid bed apparatus with Wurster method. The physical parameters were detected. These fitted the Ph. Eur. and the mechanical properties of the tablets were appropriate for coating in fluid bed apparatus. The tablets agree with the requirements of Ph. Eur. and the active agent was not dissolved in gastric juice. An animal test was also performed. The human alpha-interferon in the blood of the animals was detected with ELISA method. The human alpha-interferon specific kit was used. The active ingredient dissolved from the tablets was absorbed from the ileum. The solid dosage form containing human alpha-interferon was prepared; this can make oral application of human alpha-interferon possible.     

Dosage form design and in vitro/in vivo evaluation of cevimeline extended-release tablet formulations

The objective of the present work is to develop an extended-release dosage form of cevimeline. Two types of extended-release tablets (simple matrix tablets and press-coated tablets) were prepared and their potential as extended-release dosage forms were assessed. Simple matrix tablets have a large amount of hydroxypropylcellulose as a rate-controlling polymer and the matrix is homogeneous throughout the tablet. The press-coated tablets consisted of a matrix core tablet, which was completely surrounded by an outer shell containing a large amount of hydroxypropylcellulose. The simple matrix tablets could not sustain the release of cevimeline effectively. In contrast, the press-coated tablets showed a slower dissolution rate compared with simple matrix tablets and the release curve was nearly linear. The dissolution of cevimeline from the press-coated tablets was not markedly affected by the pH of the dissolution medium or by a paddle rotating speed over the range of 50–200 rpm. Furthermore, cevimeline was constantly released from the press-coated tablets in the gastrointestinal tract and the steady-state plasma drug levels were maintained in beagle dogs. These results suggested that the designed PC tablets have a potential for extended-release dosage forms.     

Pharmacokinetic evaluation of a new oral sustained release dosage form of tramadol

AIMS: To compare the pharmacokinetic profile of a new modified release formulation of tramadol (Tramadol LP 200 mg, SMB Technology, Marche-en-Famenne, Belgium) with that of an immediate release capsule (Topalgic) 50 mg, Grünenthal, Aachen, Germany) after single and multiple dosing and to assess the potential effect of food on its relative bioavailability. METHODS: The first study had an open, single-dose, three-treatment, three-period, six-sequence, randomised, crossover design with at least a five-day wash-out. The second study had an open, steady-state, two-treatment, two-period, two-sequence, randomised crossover design with at least a seven-day wash-out. Both studies contained 30 healthy subjects. Both enantiomers of tramadol and O-demethyl-tramadol (the only active metabolite of tramadol) were assayed in the plasma using an LC-MS/MS method. AUC infinity, AUCt, Cmax, Tmax, and T1/2 were estimated. Statistical analysis was performed using univariate anova, the Wilcoxon nonparametric method or Friedman's nonparametric anova where appropriate. RESULTS: Tramadol had a significantly lower Cmax and longer Tmax than the conventional formulation. Thus, the mean (+/- sd) Cmax of tramadol were 646 +/- 192 and 300 +/- 94 ng ml-1 for Topalgic 4 x 50mg and Tramadol LP 200 mg, respectively (95% confidence interval on the difference expressed as a percentage 42-51). AUC of tramadol from both formulations was comparable (similar AUC infinity and AUCt). Thus, the mean AUC infinity of (+/-)tramadol obtained after multiple dosing were 4611 +/- 1944 and 5105 +/- 2101 ngh ml-1 after Topalgic 4 x 50mg and Tramadol LP 200 mg, respectively (95%CI 102-123%). We also demonstrate that the pharmacokinetics of the drug are not influenced by the intake of food. Thus, the mean AUC infinity of (+/-) tramadol were 5444 +/- 1637 and 5169 +/- 1580 ngh ml-1 after Tramadol LP 200 mg given in the fasting and fed states, respectively (95%CI = 88-103%). CONCLUSIONS: The new sustained release form of tramadol exhibits adequate properties for once a day administration. Furthermore, its pharmacokinetic profile is not affected by the intake of food.     

Design and evaluation of a controlled-release theophylline tablet. Preliminary communication

A 300 mg controlled-release theophylline formulation was developed as a tablet prepared by wet granulation using the acrylic resins Eudragit S 100R and Eudragit RSPMR. The tablet was compared with a marketed controlled-release capsule using in vivo and in vitro tests. The in vitro dissolution of theophylline from the tablets followed an apparent zero order kinetics. The in vivo comparison was performed in a cross over fashion in four healthy volunteers who received one tablet or capsule every 12 hours during seven days. The results showed no statistically significant differences in AUC, tmax and in plasma theophylline concentrations at the different times. Nevertheless, concentrations were lower after the administration of the tablets than when the volunteers received the capsules. On the other hand, the apparent elimination half lives obtained after the tablets were longer than with the capsules. An excessive retardation in the release of theophylline from the tablet could be responsible for this fact.