Characterization of 5-fluorouracil release from hydroxypropylmethylcellulose compression-coated tablets

Hydrogel compression-coated tablets are able to release the core drug after a period of lag time and have potential for colon-specific drug delivery based on gastrointestinal transit time concept. This study investigated the factors influencing in vitro release characteristics of a model drug 5-fluorouracil from hydroxypropylmethycellulose (HPMC) compression-coated tablets. The core tablet, prepared by a wet granulation compression method, was designed to disintegrate and dissolute quickly. To prepare the compression-coated tablets, 50% of the HPMC/lactose coat powder was precompressed first, followed by centering the core tablet and compressing with the other 50% of the coat powder. Release characteristics were evaluated in distilled water by using a Chinese Pharmacopoeia rotatable basket method. Effect of HPMC viscosity, lactose content in outer shell, and overall coating weight of outer shell on release lag time (T(lag)), and zero-order release rate (k) were studied. Release of drug from compression-coated tablets began after a time delay as a result of hydrogel swelling/retarding effect, followed by zero-order release for most of the formulations studied. HPMC of higher viscosity (K4M and K15M) provided better protection of the drug-containing core, showing increased release lag time and slower release rate. Incorporating lactose in outer shell led to decrease of T(lag) and increase of k. T(lag) and k are exponentially and linearly correlated to lactose content, expressed as weight percentage of the outer shell. Larger coating weight (W) of outer shell produced larger coating thickness (D) around core tablet, which resulted in increase in T(lag) and decrease in k. There was good fitting of a linear model for each of the four variables W, D, T(lag), and k. Hardness of the compression-coated tablets and pHs of the release media had little effect on drug release profile. It is concluded that the release lag time and release rate are able to be tailored through adjusting the formulation variables to achieve colon-specific drug delivery of 5-fluorouracil.     

An in situ crosslinked compression coat comprised of pectin and calcium chloride for colon-specific delivery of indomethacin

Abstract

The use of pectin for colon-specific drug delivery has been extensively investigated; however, when used alone, pectin is often compromised due to its high solubility. This study explored the feasibility of using an in situ compression-coated crosslinking system, composed of pectin and calcium chloride, for colon-specific drug delivery. A pectin/calcium chloride (P/Ca) coating was compressed onto a core tablet. The colon specificity of the compression-coated tablet was verified by dissolution, pharmacokinetics and scintigraphy with ^99mTc labeling. The in situ pectin and calcium chloride gel slowed the release of indomethacin. The lag time varied between 3?h and 7?h depending on the amount of calcium chloride and the coating weight. Pectinase triggered the release of indomethacin from the compression-coated tablet, which was then accelerated by the calcium chloride in the coating layer. The compression-coated tablet had a prolonged t_max and apparent t_1/2, as well as a decreased C_max and AUC_0–t, compared with the core tablet counterpart. Evaluation with γ-scintigraphy verified colon-specific delivery of the compression-coated tablet. In conclusion, the P/Ca in situ crosslinking system worked well for colon-specific drug delivery.     

Influence of excipients,drugs, and osmotic agent in the inner core on the time-controlled disintegration of compression-coated ethylcellulose tablets

The effect of excipient, drug, and osmotic agent loaded in the inner core tablet on the time-controlled disintegration of compression-coated tablet prepared by direct compression with micronized ethylcellulose was investigated. The excipients [spray-dried lactose, hydroxypropyl methyl cellulose, sodium starch glycolate, microcrystalline cellulose, different drugs (sodium diclofenac: model drug, salbutamol sulfate, and theophylline anhydrate) and osmotic agent (sodium chloride)] were used to formulate the composition of the inner core tablet. The result indicates that drug release from all the compression-coated tablets was characterized by a distinctive lag of time followed by a faster drug release, dependent on the types of excipient and drug, and osmotic agent used in the inner core tablet. Respectively, the lag of time was 8.5, 12.4, 14.6, or 15.8 h for spray-dried lactose, hydroxypropyl methyl cellulose, sodium starch glycolate, or microcrystalline cellulose-loaded inner core tablet, as compared with 16.4 h for an inner core made of sodium diclofenac alone. The direct-compressible excipients such as spray-dried lactose, sodium starch glycolate, and microcrystalline cellulose seemed not to illustrate a marked disintegration function to rapidly rapture the outer coating layer. The lag of time was only slightly shortened from 16.4 to 14.6 h, >24 to 17.8 h, or >24 to 21.3 h for sodium diclofenac, theophylline anhydrate, or salbutamol sulfate incorporated with sodium starch glycolate into the inner core tablet, respectively, suggesting that sodium starch glycolate did not perform its superdisintegration. Once an osmotic agent of sodium chloride was incorporated into the inner core tablet, the lag of time for the compression-coated tablet was markedly shortened to <1 h, as compared with 16.4 h for drug alone. The more the amount of sodium chloride added, the less the time of lag obtained. Osmotic pressure did have a key role in controlling the drug dissolution. The present result implies that osmotic function is more suitable than superdisintegration function in designing a compression-coated tablet with time-controlled disintegration.     

Preparation and evaluation of pectin-based colon-specific pulsatile capsule in vitro and in vivo

The purpose of this study was to develop and evaluate a colon-specific, pulsatile drug delivery system, which consists of an impermeable capsule body filled with a 5-aminosalicylic acid rapid-disintegrating tablet and a pectin-based erodible plug placed in the opening of the capsule body. To obtain an appropriate gel-forming ability and suitable lag time for the colon-specific drug delivery, high-methoxy pectin (HM-pectin) was formulated with lactose and lowmethoxy pectin (LM-pectin) with HPMC to prepare the plug tablet. In order to evaluate the lag time, prior to the rapid drug release, both the formulation of the plug tablet and in vitro release medium were studied. The lag time prior to the rapid drug release was mainly determined by the HM-pectin/lactose or LM-pectin/HPMC ratio. The addition of pectinase or rat cecal content into the release medium shortened the lag time significantly, which predicted the probable enzyme sensitivity of pectin plug tablet. In vivo studies showed that the plasma concentration of drug can only be detected 6h after oral administration of the pulsatile capsule, which indirectly proved the colon-specific characteristics. These results show that the pulsatile capsule may have the therapeutic action for colon-specific drug delivery.     

Modified release from hydroxypropyl methylcellulose compression-coated tablets

The goal of this study was to obtain flexible extended drug release profiles (e.g., sigmoidal, pulsatile, increasing/decreasing release rates with time) with hydroxypropyl methylcellulose (HPMC) compression-coated tablets. Drugs of varying solubility (carbamazepine, acetaminophen, propranolol HCl and chlorpheniramine maleate) were incorporated into the tablet core in order to evaluate the flexibility/limitations of the compression-coated system. The HPMC-compression-coating resulted in release profiles with a distinct lag time followed by different release phases primarily determined by the drug solubility. Carbamazepine, a water-insoluble drug, was released in a pulsatile fashion after a lag time only after erosion of the HPMC compression-coat, while the more soluble drugs were released in a sigmoidal fashion by diffusion through the gel prior to erosion. With carbamazepine, increasing the molecular weight of HPMC significantly increased the lag time because of the erosion-based release mechanism, while, in contrast, molecular weight did not affect the release of the more soluble drugs. The lag-time and the release rate could also be well controlled by varying the HPMC amount in and the thickness of the compression-coating. A pulsatile release could also be achieved for water-soluble drugs by introducing an enteric polymer coating between the drug core and the HPMC compression-coating. This novel concept of introducing an enteric subcoating eliminated drug diffusion through the gelled HPMC layer prior to its erosion. Incorporating drug in the compression-coating in addition to the tablet core in varying ratios resulted in release profiles with increasing, decreasing or constant release rates. In conclusion, a versatile single-unit delivery system for a wide range of drugs with great flexibility in release profiles was presented.     

盐酸维拉帕米脉冲控释片的研究

目的:制备适于临睡前服用、间隔4 h 后于次日凌晨释放出治疗药物的脉冲控释片。方法:以均匀设计优化盐酸维拉帕米压制包衣片的处方组成,体外溶出度测定、体内γ-闪烁扫描示踪考察药物释放滞后时间(T_lag) ,在家犬、人体内的药代动力学研究,考察脉冲控释片在体内控时效果。结果:均匀设计得出的多元线性回归方程优化筛选了控时3,4 ,5 h 的脉冲片处方,体外脉冲控时4 h 的IV 型脉冲片,在家犬体内和体外控时3 h 的III型脉冲片在受试者体内均实现给药后4 h 脉冲释放。结论:脉冲控释片仅改变了制剂的释药开始时间,而对药物的峰浓度、生物利用度等无影响,实现设计中的脉冲释放,为防治高血压的凌晨发作提供了良好的剂型选择。     

A new index, the core erosion ratio, of compression-coated timed-release tablets predicts the bioavailability of acetaminophen

Although compression-coated tablets are a commonly used timed-release drug delivery technology, their utility is often limited by poor bioavailability. To try to improve the bioavailability of these tablets, the effect of their core composition of compression-coated tablet on in vivo pharmacokinetics was investigated. First, the extent of mass reduction of cores in different compression-coated tablet core formulations was used to establish a new index, the core erosion ratio. The data show that adding excipients with high water solubility to the core results in a greater core erosion ratio. Next, to elucidate the effect of core erosion ratio on in vivo acetaminophen (AAP) release, three compression-coated tablet formulations with similar in vitro AAP release profiles but different core erosion ratios were administered to four fasted dogs. The time for first appearance (TFA) of AAP in plasma did not differ significantly among formulations, indicating that the in vivo lag time was the same for all formulations. In separate experiments, necroscopy revealed that 3h after oral administration, the tablets were located in the ileum and colon and that all three formulations had identical GI transit times. However, the area under the AAP plasma concentration-time curve was greater in dogs given formulations with larger core erosion ratios. These results suggest that a formulation with a large core erosion ratio can significantly increase in vivo drug release from compression-coated tablets, leading to increased drug absorption from the lower GI tract.     

Formulation development of Carvedilol compression coated tablet

Purpose: The aim of present research was to produce carvedilol compression coated tablet to provide biphasic drug release.

Method: A compressed coated tablet made of a sustained release core tablet and an immediate release coat tablet. Both the core and the coat contained carvedilol. The sustained release effect was achieved with polymers (HPMC K₄M and PEO WSR 205) to modulate the release of the drug. The powder blends for core and coat tablets were evaluated for angle of repose, bulk density, compressibility index, and drug content. Compressed coated tablets were evaluated for thickness, diameter, weight variation test, drug content, hardness, friability, disintegration and in vitro release studies.

Result: The powder blends showed satisfactory flow properties, compressibility, drug content and all the tablet formulations showed acceptable pharmaco-technical properties. Carvedilol contained in the fast releasing component was released within 3?min, whereas the drug in the core tablet was released at different times up to 24?h, depending on the composition of the matrix tablet. The mechanism of drug release was fickian diffusion or anomalous behavior.

Discussion: Batch F7, containing 10?mg PEO WSR 205 and 5?mg HPMC K₄M, showed maximum similarity with theoretical profile and zero order drug release kinetic.     

Formulation design of double-layer in the outer shell of dry-coated tablet to modulate lag time and time-controlled dissolution function: Studies on micronized ethylcellulose for dosage form design (VII)

The dry-coated tablet with optimal lag time was designed to simulate the dosing time of drug administration according to the physiological needs. Different compositions of ethylcellulose (EC) powder with a coarse particle (167.5 microm) and several fine particles (< 6 microm), respectively, were mixed to formulate the whole layer of the outer shell of dry-coated tablets. The formulations containing different weight ratios of coarse/fine particles of EC powders or 167.5 microm EC powder/excipient in the upper layer of the outer shell to influence the release behavior of sodium diclofenac from dry-coated tablet were also explored. The results indicate that sodium diclofenac released from all the dry-coated tablets exhibited an initial lag period, followed by a stage of rapid drug release. When the mixture of the coarse/fine particles of EC powders was incorporated into the whole layer, the lag time was almost the same. The outer shell broke into 2 halves to make a rapid drug release after the lag time, which belonged to the time-controlled disruption of release mechanism. When the lower layer in the outer shell was composed of 167.5 microm EC powder and the upper layer was formulated by mixing different weight ratios of 167.5 microm and 6 microm of EC powders, the drug release also exhibited a time-controlled disruption behavior. Its lag time might be freely modulated, depending on the amount of 6 microm EC powder added. Once different excipients were respectively incorporated into the upper layer of the outer shell, different release mechanisms were observed as follows: time-controlled explosion for Explotab, disruption for Avicel and spray-dried lactose, erosion for dibasic calcium phosphate anhydrate, and sigmoidal profile for hydroxypropyl methylcellulose.     

Tablets of paliperidone using compression-coated technology for controlled ascending release

The aim of this work was to prepare ascending release compression-coated (CC) tablets with paliperidone (PAL) using a simple manufacturing technique and short manufacturing process. The release behavior and mechanisms in vitro of the final tablets was investigated and evaluated. The PAL CC tablets were comprised of a core layer of high viscosity hydroxypropyl cellulose (HPC-H) and a coating layer of high viscosity hydroxypropyl methylcellulose (HPMC-K100M). Several factors such as materials and core tablet compositions were studied for their influence in the formulation procedure. The drug release mechanism was studied using gravimetric analysis. The data could be fitted to the Peppas model. The ascending drug release results were expressed in terms of the slope of the release curve at different time points. Results showed that the formulation could achieve a good ascending drug release when the weight ratio of PAL was 5:1 (core:layer). The fraction of HPC and HPMC was 33 %, and the combination of Eudragit RL-PO was 10%. The ascending release mechanism was due to solvent penetration into the PAL CC tablets, and subsequent drug dissolution from the gelatinous HPC and HPMC matrix erosion. The release mechanism was therefore a combination of diffusion and erosion. This work demonstrated that the compression-coated tablets could achieve controlled ascending release over 24 h for the oral administration systems.     

盐酸维拉帕米双脉冲多相释药杯形片的研制

本文制备了盐酸维拉帕米(verapamil hydrochloride， VH)的三层片芯及四层片芯杯形片， 分别达到脉冲控释双相释药及双脉冲多相释药。用混合粉末直接压片法制备多层片芯， 干压包衣技术制备盐酸维拉帕米杯形片， 以释药时滞(T_lag)评价杯形片顶层重量、 羟丙基甲基纤维素HPMC用量及压片压力对药物的释放效果。结果表明， 顶层重量增加及HPMC用量增大时， T_lag延长； 压片压力在6～10 kg·cm^-2时， 压力增大， 时滞延长。杯形片中药物主要通过顶层单面释药， 阻滞层(顶层及多层片芯中的缓释层)的溶蚀速率是决定释药时滞的关键因素。     

Development of Press-Coated,Floating-Pulsatile Drug Delivery of Lisinopril

Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor, primarily used for the treatment of hypertension, congestive heart failure, and heart attack. It belongs to BCS class III having a half-life of 12 hrs and 25% bioavailability. The purpose of the present work was to develop a press-coated, floating-pulsatile drug delivery system. The core tablet was formulated using the super-disintegrants crosprovidone and croscarmellose sodium. A press-coated tablet (barrier layer) contained the polymer carrageenan, xanthan gum, HPMC K4M, and HPMC K15M. The buoyant layer was optimized with HPMC K100M, sodium bicarbonate, and citric acid. The tablets were evaluated for physical characteristics, floating lag time, swelling index, FTIR, DSC, and in vitro and in vivo behavior. The 5% superdisintgrant showed good results. The FTIR and DSC study predicted no chemical interactions between the drug and excipients. The formulation containing xanthan gum showed drug retaining abilities, but failed to float. The tablet containing HPMC K15M showed a high swelling index. The lag time for the tablet coated with 200 mg carrageenan was 3±0.1 hrs with 99.99±1.5% drug release; with 140 mg HPMC K4M, the lag time was 3±0.1 hrs with 99.71±1.2% drug release; and with 120 mg HPMC K15M, the lag time was 3±0.2 hrs with 99.98±1.7% drug release. The release mechanism of the tablet followed the Korsmeyer-Peppas equation and a first-order release pattern. Floating and lag time behavior have shown good in vitro and in vivo correlations.     

Improved drug delivery to the lower intestinal tract with tablets compression-coated with enteric/nonenteric polymer powder blends

The objective of this study was to develop pH-erosion-controlled compression-coated tablets for potential colonic drug delivery with improved gastric resistance and pulsatile release based on compression-coatings of powder blends of the enteric polymer Eudragit® L100-55 and the extended release polymer ethylcellulose. Tablet cores containing model drugs of varying solubilities (acetaminophen, carbamazepine and chlorpheniramine maleate) were compression-coated with different ratios of Eudragit® L100-55:ethylcellulose 10cP FP at different compression forces and tablet core:compression-coat ratios. The compression-coated tablets were characterized by drug release, media uptake, erosion behaviour and wettability. All drugs were released in a pulsatile fashion in higher pH-media after a lag time, which was controlled by the erosion properties of the Eudragit L:ethylcellulose compression-coating. The addition of ethylcellulose avoided premature drug release in lower pH-media and significantly increased the lag time in higher pH-media because of a reduction in wettability, media uptake and erosion of the compression-coatings. Importantly, ethylcellulose also reduced the pH-dependency of the erosion process between pH 5.5 and 7.4. The lag time could also be increased by increasing the compression force and decreasing the core:compression-coat ratio. In conclusion, tablets compression-coated with blends of Eudragit L and ethylcellulose resulted in excellent release properties for potential targeting to the lower intestinal tract with no release in lower pH-media and rapid release after a controllable lag time in higher pH-media.     

Development of gastroretentive drug delivery system for cefuroxime axetil: In vitro and in vivo evaluation in human volunteers

The objective of this investigation was to develop the cefuroxime axetil sustained-release floating tablets to prolong the gastric residence time and compare their pharmacokinetic behavior with marketed conventional tablets (Zocef). The floating tablets were developed using polymers like HPMC K4M and HPMC K100M alone, and polymer combination of HPMC K4M and Polyox WSR 303 by effervescent technique. Tablets were prepared by slugging method and evaluated for their physical characteristics, in vitro drug release, and buoyancy lag time. The best formulation (F10) was selected based on in vitro characteristics and used in vivo radiographic and bioavailability studies in healthy human volunteers. All the formulations could sustain drug release for 12 h. The dissolution profiles were subjected to various kinetic release models and it was found that the mechanism of drug release followed Peppas model. The in vivo radiographic studies revealed that the tablets remained in stomach for 225±30 min. Based on in vivo performance, the developed floating tablets showed superior bioavailability than Zocef tablet. Based on in vivo performance significant difference was observed between C_max, t_max, t_1/2, AUC_0–∞, and mean residence time of test and reference (p<0.05). The increase in relative bioavailability of test was 1.61 fold when compared to reference.     

Microporous bilayer osmotic tablet for colon-specific delivery

Microporous bilayer osmotic tablet bearing dicyclomine hydrochloride and diclofenac potassium was developed using a new oral drug delivery system for colon targeting. The tablets were coated with microporous semipermeable membrane and enteric polymer using conventional pan-coating process. The developed microporous bilayer osmotic pump tablet (OPT) did not require laser drilling to form the drug delivery orifice. The colon-specific biodegradation of pectin could form in situ delivery pores for drug release. The effect of formulation variables like inclusion of osmogen, amount of HPMC and NaCMC in core, amount of pore former in semipermeable membrane was studied. Scanning electron microscopic photographs showed formation of in situ delivery pores after predetermined time of coming in contact with dissolution medium. The number of pores was dependent on the amount of the pore former in the semipermeable membrane. In vitro dissolution results indicated that system showed acid-resistant, timed release and was able to deliver drug at an approximate zero order up to 24 h. The developed tablets could be effectively used for colon-specific drug delivery to treat IBS.     

盐酸地尔硫延迟起释型缓释片的研制

目的　制备盐酸地尔硫 (diltiazamhydrochloride,DIL)延迟起释型缓释片 ,解析释药机制 ,并考察外衣层组成对药物释放的影响。方法　用干压包衣技术制备盐酸地尔硫的延缓片 ,用释药时滞 (Tlag)及释药速率常数 (k)将各因素 (外衣层中的HPMC用量和粘度 ,PVPK30用量、EC粘度及压片压力 )对药物的释放效果进行评价。结果HPMC用量或粘度增大 ,Tlag延长 ,k减慢 ;PVPK30用量增大 ,Tlag减短 ,k加快 ;在一定范围内EC粘度及压片压力波动对释药行为无影响。结论　延缓片中药物主要是通过溶蚀机制释放 ,外衣层的溶蚀速率是决定释药时滞的关键因素。     

Investigating effects of hydroxypropyl methylcellulose (HPMC) molecular weight grades on lag time of press-coated ethylcellulose tablets

The research undertaken exemplifies the effects of hydroxypropyl methylcellulose (HPMC) molecular weight (MW) grades of on lag time of press-coated ethylcellulose (EC) tablets. The formulation comprised an immediate release core (containing prednisone as a model drug) surrounded by compression coating with variegated EC-HPMC blends. Five selected HPMC grades (E5, E15, E50, K100LV and K4M) were explored at three different concentrations (10% w/w, 20% w/w and 30% w/w in outer coat) to understand their effects on lag time and drug release. In vitro drug release testing demonstrated that, with increase in concentration of E5 and E15, up to 30% w/w, the mean lag time decreased progressively; whereas with remaining grades, the mean lag time initially decreased up to 20% w/w level and thereafter increased for 30% w/w level. Importantly, with increase in HPMC concentration in the outer coat, the variability in lag time (%RSD; n?=?6) was decreased for each of E5, E15 and E50, whereas increased for K100LV and K4M. In general, the variability in lag time was increased with increase in HPMC MW at studied concentration levels. Markedly, tablets with 30% w/w K4M in outer coat exhibited slight premature release (before the rupture of outer coat) along with high variability in lag time. Overall, the study concluded that low MW HPMCs (E5, E15 and E50) were found rather efficient than higher MW HPMCs for developing robust EC-based press-coated pulsatile release formulations where precise lag time followed by sharp burst release is desired.     

Delayed-release tablets using hydroxyethylcellulose as a gel-forming matrix

Delayed-release tablets containing diltiazem hydrochloride (DIL) were prepared by using CM-type hydroxyethylcellulose (HEC) of three viscosity grades. The tablets consisted of a core containing 30 mg of DIL and an outer shell formed by compressing HEC. DIL in the core was rapidly released from the tablets after a lag time of several hours in all cases. The lag time to the start of release of DIL was more prolonged with an increase in viscosity of CM-type HEC. The rate of water-uptake was greater in the CM-L4 type HEC tablet of a low viscosity grade (14 cps) than those in CM-L3 and CM-L2 type HEC (27 and 95 cps, respectively) tablets. There was little difference in lag time to the start of release of DIL from CM-type HEC tablets between JP XII 1st (pH 1.2) and 2nd (pH 6.8) fluids. A human volunteer study was performed using the delayed-release tablets prepared with CM-type HEC of two or three viscosity grades. The t_maxand MRT values of CM-type HEC tablets were significantly increased with an increase in viscosity of HEC and showed only small variations between subjects, respectively. On the other hand, although the AUC values were almost the same, the C_max values decreased with prolongation of lag time. The lag time in vivo for appearance of DIL in the blood corresponded well to the lag time in vitro for drug release, but tended to be shortened as compared with the lag time in vitro. These results indicate that the lag time can be optionally controlled by selecting HEC with a proper viscosity and/or by changing the amount of HEC forming the outer shell. This delayed-release tablet using HEC will be useful for control of time-related symptoms which need time-controlled or site-specific delivery in the gastrointestinal tract.     

Colon-specific drug delivery for mebeverine hydrochloride

Mebeverine Hydrochloride (MB-HCl), an effective spasmolytic drug, was formulated as CODES?. A colon-specific drug delivery technology CODES? was designed to avoid the inherent problems associated with pH- or time-dependent systems. To achieve more protection and control of drug release, MB-HCl was prepared as microspheres and compressed as core tablets of CODES? (modified CODES?). The core tablets contained the drug either in free form [Formula 1 (F₁)], or as microspheres with 2 different polymer:drug:lactulose ratios (1:1:0.5 [Formula 2 (F₂)] and 2:1:0.5 [Formula 3 (F₃)]. The release profiles of the coated CODES? systems were compared with uncoated compressed tablets. The uncoated tablet showed a drug release of 94% after 1 h in simulated gastric condition (pH = 1.2). The release characteristics of the coated systems revealed that the enteric coating (Eudragit®L₁₀₀) prevented any drug release in simulated gastric or duodenal conditions in the first 3 h (pH 1.2–6.1), after which drug was slightly liberated in simulated intestinal fluid (pH 7.4) {Phase 1 (P1)}. After 4 h the pH was adjusted to 7 and β-glucose-oxidase was added, which is an enzyme produced by enterobacteria present in the colon. The acid-soluble coat (Eudragit®E₁₀₀) dissolved and the drug release suddenly increased to reach 95, 72 and 60.4% for F₁–F₃, respectively. IR spectrum study showed a covalent bond between the drug and the polymer in the formulae F₂ and F₃ resulting in the sustained drug release from the microspheres with a significant difference (p>0.05) to F₁. The findings were confirmed by in vivo investigation using X-ray images for Guinea pigs ingested tablets containing barium sulphate (F₄), where the tablet began to disintegrate after 10 h of tablet intake. The results of the study indicated that MB-HCl CODES? colon-specific drug delivery can act as a successful trigger for drug targeting in the colon. Furthermore, a sustained release of the drug can be achieved from modified CODES containing the drug in the form of microspheres.     

Calendar

The objective of the present study was to develop a colon targeted system of meloxicam for potential application in the prophylaxis of colorectal cancer. Efficacy of selective cyclooxygenase–2 inhibitors has been proven in colorectal cancer. Meloxicam is a selective cyclooxygenase–2 inhibitor with pH-dependent solubility. To achieve pH-independent drug release of meloxicam, pH modifying agents (buffering agents) were used. Meloxicam tablets containing polyethylene oxide were dually coated with ethyl cellulose containing hydrophilic material, polyethylene glycol as an inner coating layer and methyl acrylate, methyl methacrylate, and methacrylic acid copolymer (Eudragit^® FS 30D) as outer coating layer for colon targeting. Optimized tablet formulations demonstrated good potential to deliver the drug to the colon by successfully exhibiting a lag time of 5?h during in vitro drug release study. An in vivo evaluation study conducted to ascertain pharmacokinetic parameters in rabbits revealed that the onset of drug absorption from the coated tablets (T_{lag time}?=?4.67?±?0.58?h) was significantly delayed compared to that from the uncoated tablets. The AUC_0→t and AUC_0→∞ for coated tablets were lower than of uncoated tablets, although the difference was not significant (p?>?0.01). The roentgenography study revealed that the tablet remained intact, until it reached the colon (5?h), which demonstrates that the system can efficiently deliver the drug to the colon. This study demonstrated that a meloxicam-loaded colon targeted system exhibited promising targeting and hence may be used for prophylaxis of colorectal cancer.