Bilayer mucoadhesive microparticles for the delivery of metoprolol succinate: Formulation and evaluation.

Metoprolol succinate is a very potent drug for the treatment of hypertension but suffers from poor bioavailability due to its erratic absorption in lower GI tract. Therefore, in the present study, it was hypothesized that by formulating mucoadhesive particles, the residence time in the GIT and release of drug may be prolonged that will enhance the bioavailability of metoprolol succinate. Metoprolol succinate loaded chitosan microparticles were prepared by ionic gelation method. The optimized microparticles were coated with sodium alginate to form a layer over chitosan microparticles to increase the mucoadhesive strength and to release the drug in controlled manner. Coated and uncoated microparticles were evaluated for particle size, zeta potential, morphology, entrapment efficiency, drug loading and in vitro drug release. The coated microparticles showed comparatively less drug release in the 0.1 N HCl while sustained release in PBS (pH 6.8) as compared to uncoated microparticles. The in vivo study on albino rats demonstrated an increase in bioavailability of the coated microparticles as compared to marketed formulation. From the study it can be concluded that alginate coated chitosan microparticles could be a useful carrier for the oral delivery of metoprolol succinate.

Eradication of superficial fungal infections by conventional and novel approaches: a comprehensive review.

During the last two decades, the occurrence of fungal infections either superficial or systemic has been increasing. Moreover, fungal infections become more difficult to treat when they show coupling with immunogenic diseases like AIDS. Superficial fungal infections are associated with skin, nail and eye and are less prominent to systemic infection. However, it may be dangerous if not treated properly. It is usually observed that conventional formulations including cream, powder, gels etc. are used to treat skin fungal infections even for the deep seated fungal infections. However, these formulations show various side-effects on the application site like burning, redness and swelling. Further, due to the immediate release of drug from these formulations they can stimulate the immune system of body generating high impact allergic reactions. Deep seated fungal infections like invasive aspergillosis and invasive candidiasis may be more difficult to treat because the drug released from conventional topical formulation can not reach at the target site due to the low penetration capacity. Similarly, in case of fungal infection of nail and eye, conventional formulations show problem of less bioavailability. Thus, to overcome the drawbacks of conventional therapy a lot of research works have been carried out to develop novel formulations of antifungal drugs to deliver them superficially. Novel formulations explored for the skin delivery of antifungal drugs include liposomes, niosomes, ethosomes, microemulsions, nanoparticles, microspheres and micelles. These formulations show extended or sustained release of drug, minimizing the side effect on application site, enhancing bioavailability and reducing the dosing frequency. Further, these formulations also show penetration into the deep skin to treat invasive fungal infections. Novel formulations explored in treatment of fungal infections of eye are liposomes and nanoparticles and whether for nail fungal infections microemulsions are the choice. In present article, we have discussed about conventional treatment of superficial fungal infection and their comparison with the novel drug delivery systems.

Polymeric microparticles-based formulation for the eradication of cutaneous candidiasis: development and characterization.

Cutaneous candidiasis is a common topical fungal infection which may be more prominent in patients associated with AIDS. It is usually treated by conventional formulations such as cream, gel, which show various adverse effects on skin along with systemic absorption. To overcome these drawbacks, various novel drug delivery systems have been explored. Poly(lactic-co-glycolic acid) (PLGA)-based microparticulate systems have shown good dermal penetration after topical application. Therefore, in the present study clotrimazole-loaded PLGA microspheres were prepared for targeted dermal delivery. Microspheres were prepared by using a single emulsification (oil-in-water, O/W) evaporation technique and characterized for different parameters. Prepared microparticulate systems were dispersed in Carbopol 934® gel and antifungal activity was carried out on experimentally induced cutaneous candidiasis in immunosuppressed guinea pigs. Particle size of optimized formulation was 2.9 µm along with 74.85% entrapment of drug. Skin retention studies revealed that drug accumulation in the skin was higher with microspheres gel as compared to marketed gel. Confocal microscopy of skin further confirmed penetration of microspheres up to 50 µm into the dermal region. In-vivo antifungal activity studies demonstrated that microsphere gel showed better therapeutic activity, lowest number of cfu/ml was recorded, as compared to marketed gel after 96 h of application. Based on the results of the study, it can be concluded that PLGA microparticles may be promising carriers to deliver clotrimazole intradermally for the treatment of invasive fungal infections.

Bioadhesive polymers: novel tool for drug delivery.

Mucoadhesive drug delivery systems came into picture in the early 1980s and are one of the most studied novel delivery systems. Several researchers have focused on the investigations of the interfacial phenomena of mucoadhesion with the mucus. Mucoadhesion can be defined as a state in which two components, of which one is of biological origin, are held together for an extended period of time by the help of interfacial forces. A number of polymers have shown characteristics of bioadhesion and have been used in the formulation of various conventional and novel drug delivery systems. Studies demonstrated that these carriers not only increase the local therapeutic activity, but also increase the systemic availability of the drugs by increasing the residence time at the site of application. The current review is an attempt to throw some light on the basics of the mucoadhesion: the mechanism of bioadhesion and the polymers that are used in the design of the bioadhesive delivery system with their properties that affect the bioadhesion.

Post-natal decline of fetal haemoglobin in homozygous sickle cell disease: relationship to parental Hb F levels

The decline of fetal haemoglobin (Hb F) from birth to 6 years has been compared in a cohort of 266 Jamaican children with homozygous sickle cell (SS) disease and in 243 matched controls with a normal haemoglobin (AA) genotype. Hb F levels were significantly higher in the SS cases from 1 month onwards but, unlike the normal controls, no sex differences was apparent. The Hb F levels in SS disease were significantly correlated with parental Hb F levels, suggesting that genetic factors regulating adult Hb F levels are active at earlier stages in development. Furthermore, some of these genetic determinants of Hb F production may be linked to the á-like globin gene complex and be in linkage disequilibrium with the áý allele (Summary)

Serum immunoglobulin levels in children with homozygous sickle cell disease

Serum immunoglobulin levels (IgA, IgG, and IgM) have been assayed in a representative sample of children (aged 1-7 years) with homozygous sickle cell disease and in age/sex-matched control children with a normal haemoglobin genotype, followed from birth in a prospective cohort study. In SS disease, significant elevation of IgA occurred from the age of two years and of IgG from the age of six years. IgM levels were not significantly different in the two genotypes. The mechanisms contributing to these changes in immunoglobulins are currently unclear as is their clinical significance.(AU)

Splenific opacification in homozygous sickle cell disease

A prospective radiological and haemotological study of 182 patients with homozygous sickle cell anaemia has been undertaken to assess the prevalence and pattern of splenic opacification and relate this to the blood indices. Opacification was observed in 31 percent of patients. In 55 percent of these, the pattern was punctuate, whereas in 32 percent it was amorphous. A curvilinear appearance was seen in the remainder. In the amorphous group, a high percentage (72 percent), the spleen was severely contracted. The pattern of opacification and degree of contraction was related to age. The haemotological indices indicate a lower haemolytic rate in patients with splenic opacifications indicating a milder disease process with a greater persistence of the splenic capillary bed (AU)

The development of haematological changes in homozygous sickle cell disease: a cohort study from birth to 6 years

A cohort study of sickle cell disease from birth has allowed observations on the disease without the symptomatic selection inherent in previous series. The development of haematological indices from birth to 6 years in male and female infants with homozygous sickle cell (SS) disease is presented and compared with values in age and sex matched controls with a normal haemoglobin (AA) genotype previously presented elsewhere. In SS disease total haemoglobin levels fell rapidly from birth to a plateau at 3-6 months before falling again to 15 months after which no age related change occured. Mean cell haemoglobin concentration fell from birth to lowest values at 15-18 months before increasing to reach the level present at birth by the age of 5 years. Red cell counts fell rapidly after birth to a plateau at 2 months, increased slightly to 2 months and then fell steadily throughout the remaining period of study. The mean cell voloume and mean cell haemoglobin also fell rapidly after birth reaching the lowest values by 6 months and then increased progressively. Female patients showed significantly higher haemoglobin levels from 15 months to 4« years. Compared to AA controls, SS patients manifested significantly lower levels of haemoglobin from 2 weeks, and red cell counts from 1 month, and significantly higher levels of MCHA from 4 months to 3 years, MCV from 8 months to 5 years, and serum iron levels from 1 to 4 years. Children with SS disease were partially protected from iron deficiency in early childhood, perhaps by increased intestinal absorption of iron, and the associated increase in intracellular haemoglobin concentration might be disadvantageous during this high risk period (Summary)

Fetal haemoglobin and clinical severity of homozygous sickle cell disease in early childhood

The relationship of the clinical features of homozygous sickle cell disease in the first two years of life to the level of fetal hemoglobin at 6 months was investigated. Mean HgbF levels were significantly lower in children manifesting early palpable splenomegaly, dactylitis, acute splenic sequestration, and in those who died. The risks of dactylitis and ASS were significantly greater in patients with lower HgbF levels. Since early splenomegaly itself may increase the risks of ASS, infection, and death, the relationship of HgbF to these features was further analyzed within the early splenomegaly group.The results suggest that a low HgbF may have a direct effect on the etiology of ASS, but any effect on infection or death is probably mediated via its relationship with the appearance of a palpable spleen. A protective effect of a high HgbF on the risk of dactylitis was demonstrated coincident with the accepted theory of its pathogenesis. Early HgbF determinations may be of value in identifying patients at high risk of serious complications during infancy (AU)

Haematological indices in normal negro children: a Jamaican cohort from birth to five years

Haematological indices, including total haemoglobin, mean cell haemoglobin concentration, red cell count, mean cell volume, mean cell haemoglobin, reticulocytes, and serum iron values, in a cohort of 243 randomly selected Negro children with normal haemoglobin genotype, followed from birth to 5 years, are reported. Total haemoglobin fell rapidly from high levels at birth to a plateau at 2-6 months, a secondary fall occurred after 6 months and a gradual increase after 18 months. The red cell count also fell rapidly, but increased after 2 months to a plateau and then slowly declined from age 1-5. Mean cell volume and mean cell haemoglobin fell continously from birth to the lowest values at 15 months and then progressively increased to the age of 5 years. Serum iron levels were low at one year of age (mean 9.7 mumol/1) increasing slowly by age 4 and sharply by age 5. Mean cell haemoglobin concentration fell gradually to 1-1 1/2 years and then increased progressively to age 5. Values for Hb, MCHC, MCV, and MCH were consistently and often significantly lower in males before the age of 2 years, compatible with greater depletion of iron stores. Serum iron values were generally lower in males but there was no sex difference at one year when highly significant differences in Hb, MCHC, MCV, and MCH occurred. The cause of sex differences in early haematological development is currently unclear (AU)

Early splenomegaly in homozygous sickle-cell disease: an indicator of susceptibility to infection

135 children with homozygous sickle-cell (SS) disease diagnosed at birth have been followed for 1-5 years. Severe bacterial infections were confined to those in whom the spleen was first palpable at or before 1 year of age and were commonest in those in whom the spleen was first palpable at or before age 6 months. Regular follow-up of children with SS disease diagnosed at birth will identify children particularly at risk of severe infections. (Summary)