The release of isoconazole nitrate from different suppository bases: in-vitro dissolution, physicochemical and microbiological studies

Pharmacokinetics and anti-hypertensive effect of metoprolol tartrate rectal delivery system

The main aim of this work was to develop rectal suppositories for better delivery of metoprolol tartrate (MT). The various bases used were fatty, water soluble and emulsion bases. The physical properties of the prepared suppositories were characterized such as weight variation, hardness, disintegration time, melting range and the drug content uniformity. The in vitro release of MT from the prepared suppositories was carried out. The evaluation of the pharmacological effects of MT on the blood pressure and heart rate of the healthy rabbits after the rectal administration compared to the oral tablets was studied. Moreover, the formulation with the highest in vitro release and the highest pharmacological effects would be selected for a further pharmacokinetics study compared to the oral tablets. The results revealed that the emulsion bases gave the highest rate of the drug release than the other bases used. The reduction effect of the emulsion MT suppository base on the blood pressure and heart rate was found to be faster and greater than that administered orally. The selected emulsion suppository base (F11) showed a significant increase in the AUC (1.88-fold) in rabbits as compared to the oral tablets. From the above results we can conclude that rectal route can serve as an efficient alternative route to the oral one for systemic delivery of MT which may be due to the avoidance of first-pass effect in the liver.

The absorption of (99m)Tc-alendronate given by rectal route in rabbits

Alendronate sodium (ALD) is a bisphosphonate medication used in the treatment and prevention of osteoporosis. Absorption of ALD as oral formulation is very poor (0.5%-1%). Its bioavailability can decrease with food effect. It has some gastrointestinal adverse effects such as gastritis, gastric ulcer, and esophagitis. The aim of this study was to develop a rectal formulation of ALD as an alternative to oral route and to investigate the absorption of it by using gamma scintigraphy. For this reason, ALD was labeled with Technetium-99m ((99m)Tc) by direct method. The radiochemical characterization of the (99m)Tc-ALD was carried out by paper chromatography, thin layer chromatography, and electrophoresis methods. The labeling efficiency of (99m)Tc-ALD was found 99% without significant changes until 6 h postlabeling at room temperature. The rectal suppositories containing (99m)Tc-ALD were prepared by fusion method using polyethylene glycol (PEG) 1500. The (99m)Tc-labeled ALD suppositories were administrated to rabbits by rectal route. Serial scintigrams over all bodies of the rabbits were obtained at different time intervals using a gamma camera. We found that the rectal absorption of (99m)Tc-ALD from suppository formulation was possible. According to our results, this formulation of ALD can be suggested for the therapy of osteoporosis as an alternative route.

W/O/W multiple emulsions containing nitroimidazole derivates for vaginal delivery

The aim of our study was to formulate a stable multiple emulsions containing two nitroimidazole derivates, metronidazole (MT) and ornidazole (OR), for vaginal therapy. MT and OR were located internal and external phases of multiple emulsion, respectively, and the in vitro release studies were realized in phosphate (pH 7) and lactate buffer (pH 4.5) solutions to investigate better the effect of pH and location of active substance on the release. The imaging studies were realized in rabbits following labeling MT and OR with Technethium-99m ((99m)Tc) to evaluate the in vivo absorption characteristics. The percentage of MT and OR released from the multiple emulsions in alkaline media were 3.2- and 2.8-fold greater than that observed in acidic media, respectively, when they were introduced in the internal phase of the multiple emulsions. The absorption rate of MT from vaginal epithelium was faster than OR. We observed that especially in alkaline medium a high release was found that was convenient for the vaginal infections seen in the alkaline pH. We concluded that W/O/W multiple emulsions were locally effective in vagina and they could be introduced as a new drug carrier system for vaginal delivery.

Swelling-controlled release system for the vaginal delivery of miconazole

Miconazole nitrate, a fungicidal, is effective for the local treatment of vaginitis. The objective of this project was to develop a swelling-controlled release delivery system for miconazole. An aqueous solution of 15% w/w poly(vinyl alcohol) was mixed with a specific amount of miconazole powder. The resultant mixture was cross-linked by freeze-thawing. The effect of the number of freeze-thawing cycles was studied at four levels. The effect of the presence of PEG was studied by mixing different concentrations of two different PEG. The swelling at the end of 48 h was significantly higher (32%) for the batch that underwent four cycles. The swelling within the first 15 min for the batches containing PEG1000 was approximately 9%. However, the swelling for the batches containing PEG1450, at much lower concentration, within the same period was between 10 and 19%. The drug release profiles up to 108 h were independent of the number of freeze-thawing cycles. The cumulative percent miconazole released, in the absence of PEG, (two, four, six, eight cycles) at the end of 108 h was between 30 and 35%. The drug release was lower for the batches containing PEG1000, irrespective of the concentrations, compared with the batches containing PEG1450. A comparison of the value of diffusional exponent (n) indicates the predominance of a Fickian diffusion mechanism of release from the hydrogels.