In vitro study of interaction between quinine and Garcinia kola

Purpose: To investigate the interaction between quinine and Garcinia kola using an in vitro adsorption study.Methods: In vitro interaction between quinine and G. kola was conducted at 37 ± 0.1 °C. Adsorption of quinine (2.5 - 40 μg/ml) to 2.5 % w/v G. kola suspension was studied. Thereafter, quinine desorption process was investigated. The amount of quinine adsorbed and desorbed was quantified using HPLC. A Freundlich isotherm was constructed to describe the resulting data and percentage of quinine desorbedwas determined from the desorption data.Results: An adsorption isotherm of the data gave a Freundlich constant (K) of 52.66 μg/g, with a slope of 0.69 indicating a high capacity and affinity of G. kola to adsorb quinine at a concentration smaller than 2.41 μg/g of G. kola. However the adsorptive capacity of G. kola for quinine at 37 ± 0.1 °C appears to be a saturable process as observed from the isotherm. Quinine desorption from G. kola peaked at 1 hour (37.51 %) and decreased to a constant amount (about 35 %) over the remaining sampling time.Conclusion: Quinine is adsorbed on G. kola in vitro. This suggests that concurrent administration of quinine and G. kola should be avoided, to prevent potential drug interaction and decreased drug bioavailability.Keywords: Quinine, Garcinia kola, Adsorption, Desorption, Drug interactio

Pharmacokinetic and pharmacodynamic alterations in older people with dementia

Introduction: The number of people with dementia internationally is increasing. Older adults with dementia are prescribed multiple medications, both to treat dementia symptoms and to manage their other medical conditions. Dementia is correlated with increasing age and frailty; this provides insight into how the efficacy and toxicity of medications may be altered in people with dementia. Areas covered: This review discusses the current evidence of the alterations in pharmacokinetics that can occur with aging, frailty and in people with dementia. The evidence is presented via the four primary pharmacokinetic processes (absorption, distribution, metabolism and elimination). Additionally, distribution into the brain, sex considerations and potential pharmacodynamic alterations in older people with dementia are discussed. Expert opinion: While the evidence is limited, people with dementia appear to be at a higher risk of toxicity of some medications due to altered pharmacokinetic processes and pharmacodynamics. There are a number of limitations to the research and there are still significant gaps in knowledge in this field. Proactive, ongoing review of the appropriateness of choice of medication, dose and whether or not a medication is required at all is necessary for achieving quality use of medications in people living with dementia

Thiopurine S-methyltransferase activity in Nigerians: phenotypes and activity reference values

Abstract Objectives This study assessed the activity of thiopurine S-methyltransferase (TPMT) in Nigerians with a view to providing data on susceptibility to thiopurine toxicity, and as well generate reference activity values for clinical use. Results TPMT activity, expressed as the amount of 6MMP in ng/mL after 1 h incubation at 37 °C per haemoglobin (U/g Hb), varied between 2.34 and 63.50 U/g Hb in the study population. Poor metabolic phenotypes, characterised by an activity values below 8.41 U/g Hb, were observed in 20% of the study subjects. Intermediate metabolizers had activity values between 8.41 and 16.13 U/g Hb. Fast and very fast metabolizers were characterised by activity values of 16.20–56.22 and > 56.22 U/g Hb, respectively. These findings suggest that a potentially huge discordance between TPMT phenotype and genotype exist in Nigerians, and emphasizes the superiority of a prior determination of TPMT metabolic phenotype in ensuring the safety of thiopurine drug administration in the population