Cyclosporine is a potent immunosuppressive drug. It has a narrow therapeutic index, and therefore the measurement of cyclosporine’s blood concentration is essential to obtain optimal therapy. Measurement of the area under the blood concentration-time curve (AUC) is reflective of total drug exposure. However, for organ transplant patients, the measurement of AUC involves many problems and difficulties. Thus, it is more clinically acceptable to use a single blood sample as a surrogate index of total drug exposure. Fifty-four adults bone marrow transplant Iraqi patients were given cyclosporine every 12 h as prophylaxis using Neoral® oral solution. Steady-state blood concentrations were monitored for each patient at zero time and then at 1, 2, 3, 4, 6, 8, 10, and at 12 h post-dosing. Cyclosporine blood levels were determined by using AXSYM automated immuno-analyzer which is a fluorescence polarization immunoassay (FPIA). The present investigation demonstrated the best correlation between C2 and the corresponding AUC0–4h and AUC0–12h compared to other concentrations. After two months of cyclosporine therapy, no unexpected biochemical changes and adverse effects were registered. It is concluded from this study that a single blood sample obtained at 2 h post-dosing (C2) and possibly at 3 h post dosing (C3) are ideal surrogate indexes for reflecting total drug exposure, and therefore may be used in clinical practice for predicting therapeutic and toxic effects of cyclosporine.

Betahistine dihydrochloride is widely used to reduce the severity and frequency of vertigo attacks associated with Ménière’s disease. Betahistine is an analogue of histamine, and is a weak histamine H1 receptor agonist and potent histamine H3 receptor antagonist. The recommended therapeutic dose for adults ranges from 24 to 48 mg given in doses divided throughout the day. Betahistine undergoes extensive first-pass metabolism to the major inactive metabolite 2-pyridyl acetic acid (2PAA), which can be considered a surrogate index for quantitation of the parent drug due to extremely low plasma levels of betahistine. The aim of the present investigation was to assess the pharmacokinetics and dose proportionality of betahistine in Arabic healthy adult male subjects under fasting conditions. A single dose of betahistine in the form of a 8, 16, or 24 mg tablet was administered to 36 subjects in randomized, cross-over, three-period, three-sequence design separated by a one week washout period between dosing. The pharmacokinetic parameters Cmax, AUC0–t, AUC0–∞, Tmax, and Thalf were calculated for each subject from concentrations of 2-PAA in plasma, applying non-compartmental analysis. The current study demonstrated that betahistine showed linear pharmacokinetics (dose proportionality) in an Arabic population over the investigated therapeutic dose range of 8–24 mg.

Abstract The present investigation aimed to formulate a liquid self-microemulsifying drug delivery system (SMEDDS) of tacrolimus to enhance its oral bioavailability by improving its dispersibility and dissolution rate. Four liquid SMEDDS were prepared using maisine CC as oil phase, labrasol ALF as surfactant and transcutol HP as co-surfactant based on the solubility studies of tacrolimus in these components. The phase behavior of the components and the area of microemulsion were evaluated using pseudoternary phase diagrams. The formulations were also assessed for thermodynamic stability, robustness to dilution, self-emulsification time, drug content, globule size and polydispersity index. The prepared SMEDDS formulations exhibited improved drug release compared to the pure drug powder. From this study, it was concluded that using a composition of 10% maisine CC, 67.5% labrasol ALF and 22.5% transcutol produced a liquid SMEDDS with good thermodynamic stability and enhanced in-vitro drug release profiles compared with pure tacrolimus powder. All which supports the use of self-micro emulsifying drug delivery systems as a promising approach to improve solubility, dissolution and stability of poorly soluble drugs like tacrolimus.

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This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-Non Commercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.

Cefuroxime axetil (CA) is a broad-spectrum second-generation cephalosporin antibiotic resistant to beta-lactamase used for treating different kinds of infections. This study was conducted to compare the pharmacokinetics (PK) and to evaluate the bioequivalence (BE) between a newly formulated generic CA 500mg tablets as a test formula with the same dose of the brand formula as the reference product applying 2-way, 2-treatment, 2-period, 2-sequence, randomized crossover design with six days washout interval between dosing. After overnight fasting for 12 hours, both CA products were administered to 28 healthy male adult Arabic subjects, followed by serial blood samples obtained from each subject before drug dosing (0-hr) and then up to 8 hours post-dosing. The calculated PK parameters Cmax, Tmax, AUC0–t, AUC0–∞, Thalf, MRT, Cl and Vd obtained from each product were statistically compared by ANOVA and 90% confidence interval tests to evaluate the BE between both products. Based on international guidance on bioequivalences like FDA and EMEA, it was concluded from this research that the test and the reference formulas are bioequivalent since the 90% confidence intervals were within the accepted ranges of 80.00-125.00%. All participants tolerated both products well, and they were discharged without any significant alterations in their clinical baseline characteristics. Therefore, the newly formulated generic CA 500mg tablets may be prescribed in clinical practice and used as a safe and effective alternative to the brand product.

Cyclosporine is mainly used as Immunosuppressant after different kinds of transplantation including bone marrow, lungs, kidneys, liver, heart, and other types of organ transplantations. Immunosuppressants diminish organ rejection and elongate the survival of the transplanted organs. Due to the narrow therapeutic ranges and significantly high interindividual and intraindividual variability in blood levels of cyclosporine, there is essential and vital need of therapeutic drug monitoring (TDM) of this drug in order to maintain the patient within the required therapeutic concentrations, which consequently lead to optimizing the clinical outcome and decrease the hazard of toxicity or rejection following organ transplantations. The current review article was aimed to present data for using a single or possibly two blood sampling strategy to be used for TDM of cyclosporine in order to assess the optimal blood levels of cyclosporine used in organ transplant recipients. The results showed that steady state blood concentration of cyclosporine obtained after 2 hours (C2) and possibly after 3 hours (C3) of drug administration are the best sampling time points which reflect total drug exposure (area under blood concentration versus time curve=AUC) and consequently reflecting the effect and the adverse effect(s) of cyclosporine. On the other hand, blood samples obtained at other time points particularly steady state trough concentration obtained before the next dose (C0) demonstrated poor correlation with total drug exposure and consequently the clinical outcome of the drug. Moreover, this study also demonstrated that for organs transplantations TDM of cyclosporine and assessing the clinical conditions of the patients should be routinely performed in order to adjust the dose to get optimal effect and to diminish the adverse effects of the drug. This review article focused on the findings which indicated that monitoring steady-state blood levels of cyclosporine after 2 hours (C2) and likely after 3 hours (C3) of drug intake may be used as ideal surrogate index in TDM of cyclosporine and for predicting the clinical outcome of the drug in all and different types of organs transplantations.