The effect of high-dose, short-term caffeine intake on the renal clearance of calcium, sodium and creatinine in healthy adults.

The consumption of caffeine has been linked to osteoporosis, believed to be due to enhanced bone resorption as a result of increased calcium excretion in the urine. However, the amount of calcium in the urine may not necessarily reflect the true effect of caffeine on calcium clearance. This study therefore examined the impact of high-dose, short-term caffeine intake on renal clearance of calcium, sodium and creatinine in healthy adults. In a double-blind clinical study, participants chewed caffeine (n = 12) or placebo (n = 12) gum for 5 minutes at 2-hour intervals over a 6-hour treatment period (800 mg total caffeine). Caffeine increased renal calcium clearance by 77%. Furthermore, the effect was positively correlated with sodium clearance and urine volume, suggesting that caffeine may act through inhibition of sodium reabsorption in the proximal convoluted tubule. This study confirmed that caffeine does increase renal calcium clearance and fosters further investigation into safe consumption of caffeine.

Supersaturated silica-lipid hybrids (super-SLH): An improved solid-state lipid-based oral drug delivery system with enhanced drug loading.

The method of supersaturation for achieving high drug loads in lipid-based formulations is under exploited and relatively unexplored, especially in the case of solid-state lipid-based formulations. Silica-lipid hybrids are solid-state lipid-based formulations designed for improving the oral delivery of poorly water-soluble drugs. However, their application to compounds of low potency and requiring large doses is limited by their low drug loading capacity. Here, an innovative technique to fabricate supersaturated silica-lipid hybrid formulations (super-SLH) has been established and the relationship between drug load and performance investigated. Using the model poorly water-soluble drug, ibuprofen, super-SLH was fabricated possessing drug loads ranging from 8 to 44% w/w, i.e. greater than the previously developed standard ibuprofen silica-lipid hybrids (5.6% w/w). Drug crystallinity of the encapsulated ibuprofen ranged from non-crystalline to part-crystalline with an increase in drug load. Super-SLH achieved improved rates and extents of dissolution when compared to pure ibuprofen, regardless of the drug load. The percentage increase in dissolution extent at 60 min varied from 200 to 600%. The results of the current study indicate that supersaturation greatly improves drug loading and that 16-25% w/w is the optimum loading level which retains optimal dissolution behaviour for the oral delivery of ibuprofen, which has the potential to be translated to other poorly water-soluble drugs.