Simultano spektrofotometrijsko određivanje valsartana i hidroklorotiazida metodom H-točke standardne adicije i djelomičnom regresijom najmanjih kvadrata

Simultaneous determination of valsartan and hydrochlorothiazide by the H-point standard additions method (HPSAM) and partial least squares (PLS) calibration is described. Absorbances at a pair of wavelengths, 216 and 228 nm, were monitored with the addition of standard solutions of valsartan. Results of applying HPSAM showed that valsartan and hydrochlorothiazide can be determined simultaneously at concentration ratios varying from 20:1 to 1:15 in a mixed sample. The proposed PLS method does not require chemical separation and spectral graphical procedures for quantitative resolution of mixtures containing the titled compounds. The calibration model was based on absorption spectra in the 200-350 nm range for 25 different mixtures of valsartan and hydrochlorothiazide. Calibration matrices contained 0.5-3 µg mL-1 of both valsartan and hydrochlorothiazide. The standard error of prediction (SEP) for valsartan and hydrochlorothiazide was 0.020 and 0.038, respectively. Both proposed methods were successfully applied to the determination of valsartan and hydrochlorothiazide in several synthetic and real matrix samples.U radu je opisano simultano određivanje valsartana i hidroklorotiazida metodom H-točke standardne adicije (HPSAM) i djelomičnom kalibracijom najmanjih kvadrata (PLS). Praćene su apsorbancije na dvije valne duljine, 216 i 228 nm, nakon dodatka standardne otopine valsartana. Rezultati primjene HPSAM pokazali su da se valsartan i hidroklorotiazid dadu odrediti simultano ako je omjer njihovih koncentracija u smjesi od 20:1 do 1:15. Za potpunu rezoluciju smjesa navedenih ljekovitih tvari preporučena PLS metoda ne treba niti kemijsko odjeljivanje niti grafičku obradu. Kalibracija se temelji na apsorpciji pri valnim duljinama 200–350 nm provedenoj na 25 različitih smjesa valsartana i hidroklorotiazida. Koncentracije valsartana i hidroklorotiazida u kalibracijskim matricama bile su 0.5–3 µg mL–1. Očekivane standardne greške (SEP) za valsartan i hidroklorotiazid iznosile su 0,020, odnosno 0,038 µg mL–1. Obje predložene metode uspješno su primijenjene za određivanje valsartana i hidroklorotiazida u nekoliko sintetskih i realnih uzoraka

Valsartan Orodispersible Tablets: Formulation, In vitro/In vivo Characterization

Valsartan orodispersible tablets have been developed at 40-mg dose, with the intention of facilitating administration to patients experiencing problems with swallowing and hopefully, improving its poor oral bioavailability. Work started with selecting drug compatible excipients depending on differential scanning calorimetric analysis. A 33 full factorial design was adopted for the optimization of the tablets prepared by freeze-drying technique. The effects of the filler type, the binder type, and the binder concentration were studied. The different tablet formulas were characterized for their physical properties, weight variation, disintegration time, surface properties, wetting properties, and in vitro dissolution. Amongst the prepared 27 tablet formulas, formula number 6 (consisting of 4:6 valsartan:mannitol and 2% pectin) was selected to be tested in vivo. Oral bioavailability of two 40 mg valsartan orodispersible tablets was compared to the conventional commercial tablets after administration of a single dose to four healthy volunteers. Valsartan was monitored in plasma by high-performance liquid chromatography. The apparent rate of absorption of valsartan from the prepared tablets (Cmax = 2.879 μg/ml, tmax = 1.08 h) was significantly higher than that of the conventional tablets (Cmax = 1.471 μg/ml, tmax = 2.17 h), P ≤ 0.05. The relative bioavailability calculated as the ratio of mean total area under the plasma concentration–time curve for the orodispersible tablets relative to the conventional ones was 135%. The results of the in vivo study revealed that valsartan orodispersible tablets would be advantageous with regards to improved patient compliance, rapid onset of action, and increase in bioavailability

Infectious diseases in paediatric pathology: experience from a developing country

Infectious and parasitic diseases have always challenged man. Although many of them are typically seen in some areas of the world and can be adequately managed by just improving socioeconomic status and sanitary conditions, they are still quite prevalent and may sometimes be seen outside their original geographical areas. Human migration due to different reasons, tourism, blood transfusion and solid organ transplantation has created new concerns for health professionals all over the world. If not for diagnostic purposes, at least these tropical and infectious diseases should be largely known because their epidemiology, pathogenesis, host/parasite interaction, inflammatory and reparative responses are quite interesting and teach us about human biology. Curiosity is inherent to pathology practice and so we are compelled to look for things other than tumours or degenerative diseases. This review focuses on infectious and parasitic diseases found in a developing country and brings up-to-date information on diseases caused by viruses (dengue, yellow fever), bacteria (typhoid fever, leprosy), parasites (Chagas` disease, cutaneous and visceral leishmaniasis, amoebiasis, Capillaria hepatica, schistosomiasis, cysticercosis) and caused by fungi (paracoccidioidomycosis, cryptococcosis, histoplasmosis) that may be useful for pathologists when facing somewhat strange cases from developing countries