Possibilities of microemulsion application in rectal administration of indomethacin

Rectal administration is a suitable route of administration for drugs that are either very irritating to the intestine (e.g., indomethacin) or are more effective when the first-pass effect in the liver is circumvented. Microemulsions are a tool for the improvement of penetration of sparingly soluble drugs. They are mainly used in topical and transdermal drug delivery. However, they find application also in other routes of administration, mainly due to their ability to solubilize sparingly soluble drugs. The selection of a suppository base depends on the physical properties of the drug. The study focused on evaluating the effect of the microemulsion as the solubilizer of sparingly soluble indomethacin in hydrophilic and lipophilic suppository bases compared with Polysorbate 80 as the excipient contained in the microemulsion. The reference suppositories were prepared by the traditional moulding technique from Adeps solidus or Macrogol suppository base without the previous drug solubilization. The microemulsion-based suppositories were prepared after the initial solubilization of the drug in the microemulsion or Polysorbate 80, followed by the addition of suppository base to maintain the same drug/solubilizer ratio. The suppositories were tested for softening time, hardness, and uniformity of mass. The dissolution test was performed using the dialysis tubing method in the basket apparatus. The amount of indomethacin released into the dissolution medium was determined spectrophotometrically at 320 nm. The results indicate that solubilization of indomethacin in the microemulsion had a positive effect on in vitro drug release but not as significant as in the case of Polysorbate 80 used alone. The enhancement ratio for Polysorbate 80 in Adeps suppositories was 2.9, for the microemulsion in Adeps suppositories was 1.1, and for Polysorbate 80 in Macrogol suppositories was 7.4 after 3 hours. The test of uniformity of mass had shown that all suppositories (reference, solubilizer-containing) are within the permitted limits. The softening time was reduced by adding the solubilizer to each type of suppository base.

Formulation and Evaluation of Fixed Dose Combination Suppositories Containing Stavudine, Lamivudine and Nevirapine for Pediatric Applications

Suppositories are the convenient way of administering drugs in infants. In view of the lack of suitable pediatric antiretroviral formulations in the market, suppositories containing fixed dose combination (FDC) of stavudine, lamivudine and nevirapine (SLN) were developed to allow administration of the correct weight-related dose in pediatric HIV patients as recommended by WHO. Suppositories containing 10 mg of stavudine, 40 mg of lamivudine and 70 mg of nevirapine were prepared by the fusion method using Witepsol H15 semi-synthetic suppository base. All the prepared suppositories were evaluated for various physical parameters like weight variation, melting point, drug content and hardness. The rate and extent of drug release was evaluated using USP apparatus I and samples were analyzed by a validated UV-multicomponent method. The use of surfactants significantly increased the drug release from formulations manufactured with Witepsol H 15 fatty base. The development of pediatric fixed-dose combination formulations represent a new era and mark an important milestone for children living with HIV/AIDS.

A suppository-base-matrix tablet for time-dependent colon-specific delivery system

Our research has focused on the main design features and release performances of time-dependent colon-specific (TDCS) delivery tablets, which relies on the relative constancy that is observed in the small intestinal transit time of dosage forms. But inflammatory bowel disease（IBD）can affect the transit time, and usually results in watery stool. Compared to the TDCS and wax-matrix TDCS tablet, a promising time-dependent colon-specific delivery system was investigated. In our study, a suppository-base-matrix coated tablet was evaluated. Water soluble suppository-base helps the expansion of tablet, facilitates uniform film dissolution and achives high osmotic pressure. Combining the expansion of carboxymethyl starch sodium (CMS-Na) and the moisture absorption of NaCl, the coated TDCS tablet obtained a burst and targeted drug delivery system. A very good correlation between in vitro drug release and in vivo outcome was observed. This TDCS coated tablet provides a promising strategy to control drug release to the desired lower gastrointestinal region.

Physicochemical properties, in vitro release and in vivo evaluation of tramadol hydrochloride rectal suppository and rectal gel

Background: Tramadol is a centrally acting analgesic drug. Rectal administration of tramadol is useful in the treatment of post-operative pain or malignant pain in cases where it cannot be administered orally. In Thailand, tramadol is available only as a capsule for oral use and as a solution for injection. Objective: Develop tramadol hydrochloride rectal suppositories and rectal gel preparations. Methods: Tramadol rectal suppository and rectal gel were prepared. Physicochemical properties (viscosity, gel strength, mucoadhesive force) and the in vitro release of tramadol hydrochloride were investigated from different bases (Witepsol H15, polyethylene glycol, poloxamer, and hydroxyethylcellulose). The analgesic activity of rectal tramadol hydrochloride using the hot plate test was evaluated in rats. Results: Tramadol hydrochloride rectal gel using poloxamer was more mucoadhesive to the rectal mucous membrane than was the gel with the hydroxyethylcellulose base. Tramadol hydrochloride was released rapidly in vitro from both the Witepsol H15 and polyethylene glycol bases. It was completely released from the polyethylene glycol suppository base within 15 minutes. The amount of tramadol hydrochloride release from the Witepsol H15 suppository base was about 93% at 120 minutes. When using poloxamer or hydroxyethylcellulose as a rectal base, tramadol hydrochloride was released from both bases rapidly and completely released within 15 minutes. Administration of a tramadol hydrochloride suppository in rats exhibited a more pronounced analgesic effect with the polyethylene glycol base than with the Witepsol H15-based suppositories. The rectal gel had a less pronounced analgesic effect when made with the hydroxyethylcellulose base than with the poloxamer base. Conclusion: Tramadol hydrochloride suppositories and rectal gels with different bases showed rapid and almost complete drug release from the bases, prolonging the latency of a nociceptive response in in vivo experiments.

In vitro Studies on Sustained Release Suppository Formulations of Tiaprofenic Acid with Sucrose Fattv Acid Ester

The objective of this study was to evaluate the performance of Sucro Ester 7 (sucrose distearate) as additive for preparing sustained release suppositories of tiaprofenic acid. Suppocire AIM (semi-synthetic glycerides) was used as suppository base and formulations were prepared containing different ratios of sugar ester: Suppocire AIM. Content uniformity, disintegration time and in vitro release characteristics of suppositories were investigated. Significant decrease in the extent of drug release was observed with the increase in the content of sugar ester, which was due to the longer disintegration time of suppositories.

Preparation and evaluation of tolmetin sodium conventional and sustained-release suppositories

Conventional suppositories of tolmetin sodium were prepared by using two different types of Witepsol as an oily base and two different ratios of polyethylene glycol 400: polyethylene glycol 4000 as an water-soluble base. In addition, sustained- release suppositories were prepared by adding Eudragit L-100 ta the suppositories. The effects of the suppository base and the ratios of the polyethylene glycol 400: polyethylene glycols 4000 on the in vitro release characteristics were investigated. The release rate of tolmetin sodium from the conventional suppositories prepared with polyethylene glycol was slower than the other suppositories prepared with Witepsol. All of the suppositories with Eudragit L-100 showed slow-release profiles and the drug release rates clearly depended on the Eudragit L-100 content. When dissolution results were evaluated kinetically, zero order kinetic was observed with the sustained- release suppositories of tolmetin sodium prepared with polyethyleneglycol 400: polyethyleneglycol 4000 by adding Eudragit L-100.