The influence of fillers on theophylline release from clay matrices

Abstract: The objectives of this study were to investigate the suitability of magnesium aluminium silicate (MAS) (Veegum®) to control drug release of a model drug, theophylline, from tablet matrices. To this end, the performance of three commonly used fillers namely: lactose, microcrystalline cellulose (Avicel PH102; MCC), and pre-gelatinized starch, Starch 1500 PGS), were evaluated against Veegum®. The physico-mechanical properties of the tablet matrices were studied along with dissolution studies to determine the effect of single or binary mixtures of the excipients on the drug release pattern. A DSC hydration methodology was also employed to characterize the states of water present in the tablet matrices and to determine any impact on drug release. Formulations containing MAS alone produced compacts with the lowest hardness (4.5 kp) whereas formulations containing MCC alone produced the hardest tablets (17.2 kp). Dissolution studies suggested that matrices containing MAS alone released the theophylline quickest as compared to lactose, MCC or PGS. It was difficult to establish a trend of the bound and free water states in the tablet matrices; however the formulation containing only MAS had the highest bound water at 29 %. The results therefore show that theophylline does not interact with MAS. As such the dominant factor in controlling drug release using MAS requires interaction or intercalation with a cationic drug. In the absence of this however, other excipients can play a role in controlling drug release. Keywords: Veegum, clay matrices, DSC hydration, Magnesium aluminium silicate, filler

Tree diversity and canopy cover in cocoa systems in Ghana

First Online: 15 October 2015Cocoa (Theobroma cacao L.) growing systems in Ghana and West Africa consist of diverse tree species and densities. This study was conducted to determine factors that influence tree species configurations and how tree characteristics affect canopy cover in cocoa farms. Eighty-six farmers and corresponding farms were selected in a systematic approach in four districts across two agro-ecological zones in Ghana. Results show that men tend to have larger farm sizes, higher tree density and diversity than women. Tree density and canopy cover of shade trees were low on large farms, but diversity increased with increasing farm sizes. Even though there was a significant correlation between diameter at breast height and crown area for all species investigated, tree species differed considerably in their crown area and thus the amount of ground cover provided. Current recommendations for shade are usually expressed in number of trees per ha, and our results suggest that these should be refined to reflect the effects of species, the size of their diameter at breast height and the crown area

Influences of shading and fertilization on on-farm yields of cocoa in Ghana

Article Purchased; Published online: 31 August 2016Most cocoa farms in Ghana are cultivated in complex agroforest systems, with plant growth and cocoa productivity being affected. The objective of this study was to investigate how shade trees affect cocoa yield, temperature and soil nutrients in low-input cocoa systems. Establishing plots on 24 farms in four locations (districts) in Ghana, we assessed the influence of varying canopy cover and fertilization on cocoa yields. Results showed no relationship between canopy cover and cocoa yields in the light crop season (February to August). For the main crop season (September to January), there was an interaction between shade and yields: Yields were higher on no-shade plots than on shaded plots in two districts, whilst there were no differences at the two other districts possibly due to differences in precipitation and soil nutrient status. On the other hand, there was a positive effect of increased canopy cover on yields within the shaded plots. Soil nutrient analyses revealed no significant differences between shaded and no-shade plots and adequate levels of N, K+, Fe2+, Cu2+ and Zn2+ were recorded. However, soil contents of P, C, Mg2+ and Ca2+ were below recommended values. Peak temperatures recorded in the cocoa canopies were above the recommended range for this species. Although shade trees had a slight modifying effect on peak temperatures, the magnitude appeared too small to have any practical effects

A Green Revolution in the West African cocoa belt

STCP tools for the rehabilitation of West African cocoa farms Cacao tree stocks in West Africa are mainly established from seeds procured from farmers’ fields. This planting material lacks the disease tolerance and yield potential of the hybrid seed. Productivity is also affected by the old age of West Africa’s tree stock. Replacing and rehabilitating the tree stocks of West Africa is fundamental to the achievement and long-run sustainability of a cocoa Brown Revolution. The STCP has developed a Planting, Replanting and Diversification (PRD) training package to provide farmers the knowledge and technical skills needed to rehabilitate old cocoa farms or reclaim degraded areas using hybrids. However, a major constraint to hybrid adoption is a lack of access to hybrid seeds. To overcome this constraint, STCP introduced a Seed Brokerage System (SBS) for the collective acquisition of hybrid seeds by farmer field school groups from government production units. An initial evaluation of 375 randomly selected trainees revealed that the mean participant had successfully established 0.4 ha of hybrid cocoa seedling with an 81% seedling survival rate after two dry seasons. Approximately half of the surveyed trainees had replanted old farms while half had established new farms on degraded fallow land. The SBS also brokered timber seedlings for farmers desiring to include high-value timber (Terminalia ivorensis and T. superb) as permanent shade in their production system. The mean participant reported the successful establishment of 12 timber seedlings which is equivalent to 30 trees per hectare. Farmers favored the SBS innovation and are seeking its continuance

Access to improved hybrid seeds in Ghana: Implications for establishment and rehabilitation of cocoa farms

Poor access to improved seeds in West and Central Africa has compromised crop yields and productivity as most farmers source the bulk of their seeds from informal channels. The use of farmer produced seeds has mostly resulted in high seedling mortality thereby presenting challenges to cocoa rehabilitation programmes across the sub region. With the aid of a mobile data collection system (MDCS), the first of its kind to enhance accuracy of survey results in an improved seed supply system through brokerage and linkages among diverse actors, this study assesses Ghanaian farmers’ access to improved hybrid cocoa seeds and provides evidence on the socio-cultural factors that affect field performance of such planting materials. Results show that farmers value a seed brokerage system (SBS), which is facilitated through group bulk purchase, timely acquisition and delivery of seeds. The study also revealed that farm size, land use type and gender have significant effect on survival rate of transplanted hybrid cocoa seedlings over two dry seasons. Regardless of the rehabilitation process, mean survival rate was high (79%) although an 11% (p < 0.000) difference occurred between gender with men recording a higher rate. The majority of farmers prefer cultivating cocoa on forest and fallow lands, implying continues degradation of forest areas. There is therefore an urgent need for a change of mind set, to advocate for land recycling to spare forest areas to thrive

The nexus between cocoa production and deforestation

In Ghana, cocoa contributes substantially to the agricultural foreign earnings and plays a major role in providing income for millions of farmers and households. But its production has environmental impacts, like deforestation. Creating a policy environment that supports sustainable practices in agriculture to leverage the cocoa forests for biodiversity conservation is essential

Ghana’s Quest for Oil and Gas: Ecological Risks and Management Frameworks

Ghana discovered commercial oil and gas in 2007, and, subsequently, commenced production in the last quarter of 2010. In the light of the potential economic boost that will accompany petroleum production, its discovery was welcome news for Ghanaians. However, oil exploration and production involve several activities that can have detrimental impacts on the ecosystem. In this paper, the potential sources of pollution in the upstream sector of the oil and gas industry and their effects on the environment are discussed. Also discussed are existing national environmental management legislations in the extractive industry, and the implementation and enforcement challenges these regulations face. Strategies to curtail the effects of oil and gas development on the ecosystem are also put forward. These include the need for government to formulate petroleum industry-specific environmental protection guidelines and appropriate regulatory frameworks. Such regulations in managing the environment should employ an integrated approach involving (i) prescription of environmental codes and setting of standards by government to be met by operators, and (ii) the need for oil companies to develop environmental management system (EMS) to ensure that they operate within the environmental standards for the industry. Administrative and institutional restructuring and reforms, as well as the provision of the necessary financial and human resources for the various environmental agencies, should be encouraged to ensure effective implementation,  enforcement and monitoring

Assessment of Groundwater Quality and its Suitability for Domestic and Agricultural Purposes in parts of the Central Region, Ghana

Groundwater in parts of the Central Region of Ghana was assessed to determine its suitability for domestic use and irrigation activities. Stiff and Piper diagrams show that the predominant water type in the area is Na-Cl, which is characterized by relatively high salinities. This water type occurs in aquifers underlying six coastal districts, namely; Abura-Asebu-Kwamankese (AA), Mfantseman (MF), Gomoa East (GE), Awutu Senya (AwS), Effutu (EF) and Cape Coast (CC). Other water types are Ca-HCO3, Ca-SO4 and Ca-Cl, that occur in districts located further away from the coast. Silicate weathering and ion exchange are identified as the geochemical processes responsible for the various ions in the groundwater. Possible processes that could be responsible for the source of Na+ and Cl- are sea water intrusion and dissolution of minerals. The results also show that the groundwater is mainly supersaturated with respect to both calcite and gypsum, indicating high concentrations of both bicarbonate and sulfate ions in solution. This is associated with considerable enrichment of the groundwater with sulfate, bicarbonate, and calcium ions. On a Wilcox diagram, the groundwater samples, mainly from the districts coded as AA, TLD, AS and AN, which are located away from the coast, plot within the “excellent to good” category, suggesting that water from the area is of acceptable quality for irrigation purposes. Similarly, Sodium Adsorption Ratio (SAR) and conductivity values for the groundwater in the AA, TLD, AS and AN districts indicate low SAR and low to medium salinity respectively. Groundwater in aquifers underlying these districts is therefore suitable for irrigation. Generally, groundwater samples from locations along the coast have high salinity and are not suitable for domestic and irrigation purposes. However, about 72% of the water samples predominantly in districts located away from the sea is suitable for the purposes stated