Cellular uptake and metabolism of DNA frayed wires.

DNA frayed wires are a novel, multistranded form of DNA that arises from interactions between single-stranded oligodeoxyribonucleotides with the general sequence d(N(x)G(y)) or d(G(y)N(x)), where y > 10 and x > 5. Frayed wires exhibit greater stability with respect to thermal and chemical denaturation than single- or double-stranded DNA molecules and, thus, may have potential usefulness for DNA drug delivery. However, the stability and uptake of frayed wires have not been investigated in biological systems. Our objective was to examine the cellular uptake and stability of frayed wires in cultured hepatic cells. In these studies, the parent oligonucleotide d(A(15)G(15)) was used to form DNA frayed wires (DNA(FW)) while a random 30-mer oligonucleotide was used as the control nonaggregated DNA (DNA(SS)). Uptake and metabolism studies of DNA(FW) were performed in cultured human hepatoma, HepG2 cells and compared to DNA(SS). Our results indicate that DNA(FW) are not cytotoxic and that their intracellular uptake in HepG2 cells is 2-3.5-fold greater than that of DNA(SS) within the first 2 h (p < 0.05). Similarly, nuclear localization of DNA(FW) is 10-13-fold higher than that of DNA(SS) (p < 0.05). As both internalized and extracellular DNA(FW) appear to be more stable in vitro than DNA(SS), the enhanced uptake may be due to either increased stability or enhanced intracellular transport. These studies also indicate that uptake of DNA(FW) likely occurs via active processes such as receptor-mediated endocytosis similar to mechanisms which have been proposed for DNA(SS). The internalization pathways of DNA(FW) may differ somewhat from that of DNA(SS) insofar as chloroquine does not appear to alter DNA(FW) uptake and degradation, as is the case with DNA(SS).

Rapid therapeutic response onset of a new pharmaceutical form of chloroquine phosphate 300 mg: effervescent tablets.

OBJECTIVE: To compare the efficiency, safety and taste of two pharmaceutical forms of chloroquine phosphate 300 mg: effervescent tablets against uncoated tablets. METHOD: An open randomized study with 60 adults who suffered from acute uncomplicated Plasmodium falciparum malaria in three health centres in Nkongsamba health district, Cameroon. RESULTS: Mean times to fever clearance, symptoms clearance and asexual parasites clearance were longer in the uncoated tablets group: 36 h (range 24-48 h, SD = 16.8) vs. 60 h (range 24-96 h, SD = 31.2, P = 0.001) for fever clearance, 36 h (24-48 h, SD = 16.8) vs. 48 h (24-72, SD = 24, P = 0.001) for symptoms clearance and 48 h (24-72, SD = 1) vs. 72 h (48-96, SD = 24, P = 0.001) for parasitaemia clearance. Uncoated tablets took significantly longer to achieve 50% reduction of the initial asexual parasite density: (mean/SD) 19.2 h/7 vs. 52.8 h/16.8, P < 0.00001. The adverse effects in the two groups were similar, P > 0.05. The cure rate at day 7 in the two groups was similar, P > 0.05. There was no chloroquine resistance in the effervescent tablets group but one RI and one RII resistance in the uncoated tablets group. The taste of the two pharmaceutical forms was significantly different, P < 0.00001. Effervescent tablets tasted sweet (score = 7.93), whereas uncoated tablets were bitter (score = 2.07). CONCLUSION: Effervescent tablets of chloroquine phosphate 300 mg work faster than uncoated tablets and because of their safe use and sweet taste achieve good therapeutic compliance.

[The carbon dioximeter: a device for quantifying the carbon dioxide released from effervescent pharmaceuticals]. / Dioxycarbomètre: appareil de dosage du dioxyde de carbone dégagé par les formes pharmaceutiques effervescentes.

Since effervescent pharmaceuticals are more sensitive to ambient humidity during the manufacturing process and storage, the strict control of their carbon dioxide content becomes a prerequisite to guarantee their physicochemical stability. Indirect gravimetry is a simple and precise method that consists in taking the weight before and after the effervescent reaction allowing to determine the released amount of carbon dioxide. Some authors have used it with devices that lead to longer analysis times and poor accuracy of measurements (due to the excess of released carbon dioxide). The device that we have built (proposed name "CARBONDIOXIMETER") is very easy to set up, and yields quick, accurate, precise and reproducible results. An assay takes three minutes in an acidic medium and five minutes in carbon dioxide free water). Moreover, through the interconnection of scales, registration and treatment of the results can be performed by a printer or a computer. Thus, the "Carbondioximeter" is contributing to the control of physicochemical stability of effervescent pharmaceuticals during the manufacturing process and storage.