[Lotion with hydroquione - tretinoin]. / Lotion a l'hydroquinone et a la trétinoïne.

The observed precipitation in a lotion containing 4% of hydrochinon and 0,03% of tretinoine is evaluated. To dissolve both actives, 10% propyleneglycol is used and the alcohol concentration varied. From the results it is demonstrated that at least 54 ml of ethanol 96 degrees is necessary to dissolve both actives. It is also demonstrated that the addition of 0.2% of vitamin C, as antioxidant, is necessary to avoid coloration of the lotion, as a function of time, due to the presence of hydrochinon.

[Pharmacy compounding of an omeprazole suspension]. / Preparation magistrale d'une suspension d'omeprazole.

The problems of preparation of different pharmaceutically compounded formulations of prescribed omeprazole suspensions are discussed. Problems that can be cited are: inadequate preparation, chemical and physical stability problems, taste problems and low bioavailability. The formulation of the omeprazole suspension is optimized, taking into account the cited problems. At the same time, some formulations are presented, ensuring chemical stability of omeprazole and its bioavailability.

Influence of preparation method on itraconazole oral solutions using cyclodextrins as complexing agents.

In the literature, solubility values of itraconazole complexed with 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) were found which were still much too low to obtain the target concentration of 1 g itraconazole/100 ml, the concentration of the marketed itraconazole formulation Sporanox (Janssen Pharmaceutica). Therefore, we compared two preparation methods: the classical and the dissolving method to investigate if the method of preparation can have an influence on the solubility of itraconazole complexed with cyclodextrin (CD). With the classical method, the active compound and the CDs are jointly dissolved with a co-solvent, propylene glycol, in water. With the dissolving method, the active compound is first dissolved separately in a solvent in which it dissolves well, while the CDs are dissolved in water, before mixing. Three different CDs were used and compared for their complexing capacity with itraconazole. The complex formation of itraconazole with HP-beta-CD, sulfobutylether-7-beta-cyclodextrin (SBE-7-beta-CD) and maltosyl-beta-cyclodextrin (malt-beta-CD) was investigated at pH 2, in the presence of 10% propylene glycol for an oral solution. These three CDs were chosen as they can also serve in formulations for parenteral use. The method of preparation had an important influence on the complex formation. With the dissolving method, a much higher solubility of itraconazole was obtained using the same CD concentration than with the classical method. Inclusion capacity obtained with the dissolving method was comparable for HP-beta-CD and SBE-7-beta-CD: 1 g itraconazole/100 ml of 25% HP-beta-CD or of 30% SBE-7-beta-CD. In 100 ml of 40% malt-beta-CD only about 500 mg of itraconazole could be dissolved. With the classical method only around 160 mg itraconazole could be dissolved with 100 ml 40 % HP-beta-CD or SBE-7-beta-CD. Due to the fast preparation, once the CD amount is known by pretests, the dissolving method shows also an advantage for industrial production.

Quality evaluation of chloroquine, quinine, sulfadoxine-pyrimethamine and proguanil formulations sold on the market in East Congo DR.

OBJECTIVE: Drug quality may be poor in many regions of the world. Our first aim was to verify whether the dose of the active compounds in various antimalarial medicines on the market in East Congo conforms to the quality requirements of the European Pharmacopoeia (Ph. Eur.). The second aim was to check the extent to which simple methods of analysis could be used to evaluate drug quality. METHODS: The formulations analysed included tablets, injections and syrups of chloroquine (CQ), quinine, sulfadoxine-pyrimethamine (SP) and proguanil. Ultraviolet (UV) spectrophotometry was used to quantify CQ and quinine in tablets and injections. Thin layer chromatography was used to identify the preservative(s) in the syrups. As the drug form (base or salt) in the tablets, is rarely declared, the estimated dose was calculated using both forms. High-performance liquid chromatography (HPLC) was used to check for assay interference and for measuring SP combinations. RESULTS AND DISCUSSION: When the dose declaration on the label was assumed to be of the salt form, 33% of CQ batches were underdosed and two of eight batches of quinine were underdosed by about 25% and 15% respectively. When the base form was assumed, only one batch of CQ tablets conformed. The underdosed batches contained about 50-66% of the claimed amount for CQ. The dose of quinine in the different batches of tablets was in the range 62-86%. For the CQ syrup, interference by the preservative Nipagin, confirmed by HPLC-UV, was observed with UV-spectrophotometry at 257 nm but not at 342 nm. The results for CQ syrup using UV-spectrophotometry at 342 nm and HPLC-UV at 257 nm were comparable and showed compliance with the European Pharmacopoeia limits of 95-105%. One of two batches of CQ injections and one of four batches of quinine injections were overdosed by about 14% and 8% respectively. The SP tablets were analysed by using HPLC-UV only. All five batches were underdosed in sulfadoxine (91-94%) but still met the United States Pharmacopeial (USP) limit of 90-110%. Two batches were slightly overdosed in pyrimethamine (106% and 108% respectively) while one batch contained neither active ingredient. The one batch of proguanil analysed, met the Ph. Eur. quality requirement (98.7%). CONCLUSION: Simple methods of analysis like UV-spectrophotometry can be used to check drug quality routinely. A substantial proportion of the antimalarial drugs sold on the Congo DR market is of poor quality. Some batches contain little or no drug. This is a serious threat to public health in the region of Congo DR.

Preparation and evaluation of paclitaxel-containing liposomes.

Paclitaxel, an antitumoral drug, is poorly soluble in aqueous media. Therefore, in a commercialised formulation (Taxol), paclitaxel (30 mg active compound) is dissolved in polyethoxylated castor oil (Cremophor EL) and ethanol. After dilution of Taxol in aqueous media paclitaxel tends to precipitate. Several side effects, attributed to the surfactant Cremophor EL, occur, e.g. bronchospasm, hypotension, neuro- and nephrotoxicity, and anaphylactic reactions. To eliminate these side effects, the solubility of paclitaxel was enhanced using liposomes instead of Cremophor EL. The amount of entrapped paclitaxel in crystal-free liposomes was 0.5 mg/ml liposome suspension, i.e. almost 85 times the native solubility. Thus, 30 mg paclitaxel had to be dissolved in 60 ml liposome suspension, of either multi-lamellar vesicles (MLV's) or of small unilamellar vesicles (SUV's) with 5% sucrose as cryoprotector. No precipitation was observed after dilution of the MLV-formulation with (physiological) water or with 5% aqueous dextrose solution, which proves their suitability for administration with perfusions. The chemical stability of paclitaxel in the prepared MLV's stored at 4 degrees C was demonstrated during a period of 5 months. The chemical degradation to conjugated dienes and hydroperoxides, two oxidative degradation products of EPC, was negligible (less than 1%).

Investigation on the photostability of tretinoin in creams.

In this investigation, the photodegradation of some tretinoin cream formulations was evaluated. Several oils were selected to prepare the cream formulations: olive oil, maize oil, castor oil, isopropyl myristate and Miglyol 812. A solubility study showed that tretinoin is best soluble in castor oil (0.60g/100ml), followed by isopropyl myristate, maize oil, Miglyol 812 and olive oil, respectively, 0.35, 0.30, 0.29 and 0.22g/100ml. The photostability of tretinoin in oils is comparable with the photostability of a tretinoin lotion (ethanol/propylene glycol 50/50), castor oil and olive oil giving slightly better results than the other oils. Investigation of the photodegradation of tretinoin in o/w creams, prepared with the same oils as mentioned above, revealed that tretinoin is far more stable in the cream formulations than in the respective oils, however it is not clear whether this is due to the formulation or due to a different irradiation technique. Tretinoin seemed to be most stable in the olive oil cream, followed by the castor oil cream. However microscopic investigation revealed the presence of tretinoin crystals in the olive oil cream, while the other creams were free of it. As a conclusion, one can say that the cream prepared with castor oil seems to be the most suitable one, in terms of solubility of tretinoin and in terms of photostability.

Comparison of free iodine as a function of the dilution of two commercial povidone-iodine formulations.

Binding studies by means of equilibrium dialysis on two different Povidone-lodine-solutions reveal that the amount of available iodine and free iodine is very different as such and after dilution. The free iodine concentration in the Braunol concentrate was found to be ca. 22 mg/L and in the iso-Betadine concentrate only ca. 2.1 mg/L, despite the total amount of available iodine in iso-Betadine being higher than that of Braunol. As the bactericidal level of free iodine is characterised by concentrations >5 ppm, Braunol can be employed as a disinfectant as such, iso-Betadine has to be diluted before use. In both concentrates more than 99% of available iodine is present as reservoir for free iodine. Concerning the results as a function of dilution, it was demonstrated that, for both solutions, free iodine reaches a maximum after a 50-fold dilution (ca. 31 mg/L and ca. 51 mg/L for iso-Betadine and Braunol respectively). After dilution, a more constant level of free iodine was observed in the Braunol than in the iso-Betadine solution, and this is attributed to the present molar ratio of I(2)/I- and the addition of iodate in the former. The pH for both solutions approximates that of the skin, as such and after dilution. In summary, it can be stated that Braunol is superior to iso-Betadine as to the release of free iodine in both the undiluted as well as in the diluted form.

Inclusion complexation of diazepam with different cyclodextrins in formulations for parenteral use.

A parenteral formulation for the water-insoluble benzodiazepine diazepam was developed. Different cyclodextrins (CDs) suitable for parenteral injection: hydroxypropyl-beta-cyclodextrin (HP-beta-CD), hydroxy-propyl-gamma-cyclodextrin (HP-gamma-CD), sulfobutylether-7-beta-cyclodextrin (SBE-7-beta-CD) and maltosyl-beta-cyclodextrin (malt-beta-CD) were used as alternatives to cosolvents to increase solubility. The increase in solubility displayed a concentration dependency for the four CDs used. Diazepam's solubility is enhanced linearly as a function of each CD concentration. The highest improvements in solubility (dissolved concentration circa 3.5 mg/ml in 40% CD) were found by adding HP-beta-CD or SBE-7-beta-CD. The additional use of polyvinylpyrrolidone (PVP) did not further increase the solubility of diazepam with HP-beta-CD. A parenteral aqueous diazepam solution was prepared containing 10 mg diazepam/5 ml 30% HP-beta-CD or SBE-7-beta-CD solution. The preparations are in agreement with the requirements for parenteralia. Sterilisation by filtration is required since autoclaving degrades the active compound. The stability of the preparations, with and without pH adjustment to pH 5, was investigated during 18 months and during this period no noticeable degradation was observed.

Experimental designed optimisation and stability evaluation of dry suspensions with artemisinin derivatives for paediatric use.

There is a great need for oral anti-malaria preparations especially for small children, which are easy to administer and keep their stability under tropical conditions. The purpose of this work was therefore to develop a dry suspension, containing one of the artemisinin derivatives, namely artesunate, artemether and dihydroartemisinin using fast wetting suspending agents, i.e. xanthan gum and Avicel CL611. For the optimisation of these two variables, namely the suspending agent's content, a Doehlert design was applied. Via preliminary tests on sedimentation behaviour, the limits of both products were determined, respectively 0.1-0.4% (w/v) and 1.0-2.5% (w/v). As responses, sedimentation as a function of time, viscosity and price of the suspension, were evaluated. The stability tests of the reconstituted suspensions showed bad results for artesunate, even when the pH was adapted. In contrast, dihydroartemisinin showed only 10% degradation within 10 days and artemether was stable at least 21 days. Practically the last one was able to foresee a chemically and physically stable suspension at least during the administration period (5 to 7 days) and was therefore selected for further optimisation concerning taste and appearance. Based on the results of selection tests for the colourant, sweetener and taste masking agent, the following composition was proposed for a suitable dry powder with artemether (AM) as active compound to prepare 100 ml reconstituted suspension: AM 300 mg, Avicel CL611 2 g, xanthan gum 200 mg, crystalline saccharose 35 g, citric acid monohydrate 150 mg, Nipagine 80 mg, Nipasol 20 mg, sodium saccharinate 250 mg, tutti-frutti 250 mg and Sunset yellow 10 mg.

Development of a reversed-phase thin-layer chromatographic method for artemisinin and its derivatives.

In this study a clear separation between seven analogues of artemisinin on thin-layer chromatography (TLC) is presented. The developed TLC method is carried out on a RP-C18 thin-layer plate using acetonitrile-water (50:25 v/v) as the mobile phase. Spots are visualized by derivatization with an acidified 4-methoxybenzaldehyde reagent in methanol-water. This method allows the separation of a diverse group of compounds that have versatile hydrophilic/lipophilic characteristics; namely artemisinin, artesunate (AS), artelinic acid (AL), arteether (AE), both isomers of artemether (AM) (alpha and beta), dihydroartemisinin, and desoxyartemisinin. Separation of some degradation products and impurities, down to 2%, allows quality control and stability investigation of all actives in raw material and pharmaceutical formulations. The method is further developed via densitometric measurement for quantitative determination purposes for AL and AS. The derivatization technique is evaluated, showing good stability and reproducibility of the coloring process. Percent relative standard deviation values are less than 5% for replicates, and linearity is obtained in the range of 0.5 to 8 microg. A comparative study with high-performance liquid chromatography (HPLC) on a C18 column, applying the same mobile phase, proves the suitability of the TLC method, in which almost all presented analytes are separated from each other. In contrast, HPLC requires at least a 20-min analysis to chromatograph all of the compounds and only betaAM and AE are clearly separated from each other and from the other compounds.

Design of a dissolution system for the evaluation of the release rate characteristics of artemether and dihydroartemisinin from tablets.

As none of the pharmacopoeial dissolution methods are suitable to evaluate the release rate of artemether and dihydroartemisinin from tablets, a 'two-phase partition-dissolution' method, based on the one of [J. Pharm. Sci. 85 (1996) 1060] was developed. It consists of an organic solvent in the upper part and the aqueous phase, in which the dissolution test was executed. The main requirements for the selection of the solvent are: the density should be lower than 1; the analyte should dissolve in the organic part as much as required for 'sink' conditions; if possible, the cut off should be near 200 nm, which allows direct HPLC measurement at 215 nm. The most suitable solvent for artemether is isooctane in a ratio of 100/150 ml aqueous phase. Samples could be analysed without further treatment. For dihydroartemisinin, chlorobutane was selected in a ratio 150/150 ml water. In the latter method, the solvent disturbed in the HPLC analysis and therefore samples were evaporated and then reconstituted in methanol. Repeatability of the test was satisfactory and discrimination ability tests on Artenam tablet batches and self-made dihydroartemisinin tablets, respectively, showed good results, confirmed via calculation of the similarity factor f2 (value <50). Dissolution determination of Cotecxin tablets was proven not to be conform as immediate-release tablet.

Preparation and in-vitro release rate of fentanyl-cyclodextrin complexes for prolonged action in epidural analgesia.

Fentanyl was complexed with cyclodextrin derivatives with the intention to obtain parenteral solutions able to provide prolonged analgesia following epidural administration. Three cylodextrins (CDs) suitable for parenteral use were used: hydroxypropyl-beta-cyclodextrin (HP-beta-CD), sulfobutylether-beta-cyclodextrin (SBE-7-beta-CD), and maltosyl-beta-cyclodextrin (malt-beta-CD). Analysis of fentanyl was done with HPLC-UV. The inclusion capacity of HP-beta-CD was determined from phase-solubility diagrams at pH 6.5, 7.2 and 8.0, and those of SBE-7-beta-CD and of malt-beta-CD at pH 8.0. Solubility of fentanyl increased linearly (i) as a function of the CD concentration, and (ii) with decreasing pH. Complexation was highest with HP-beta-CD and malt-beta-CD, much higher than with SBE-7-beta-CD, with stability constants at pH 8.0 of 801, 729 and 1309 M(-1), respectively. The CD concentration was calculated to obtain a fentanyl-CD formulation, with the desired amount free fentanyl as loading dose in solution and the rest complexed with CD, as reservoir for prolonged action. A suitable membrane and a release-rate apparatus were selected for in-vitro release-rate studies. Best results were obtained with Spectrapor membranes and a home-made release-rate apparatus. Release rate was evaluated in static and dynamic conditions. For both modes, the release rate of fentanyl decreased as a function of CD concentration, due to complex formation of fentanyl, which suggests the possibility to provide prolonged pharmacodynamic effects in vivo.

Densitometric thin-layer chromatographic determination of artemisinin and its lipophilic derivatives, artemether and arteether.

A thin-layer chromatograpy (TLC) method is developed to analyze artemisinin (AT) and its derivatives, artemether (AM) and arteether (AE), using a silica-gel plate with a mobile phase containing pure chloroform. After development, all products are visualized after dipping in a 4-methoxybenzaldehyde dipping reagent of 1% (v/v) in an acidic solution of sulphuric acid (98%, v/v) and acetic acid (96-98%, v/v) (respectively, 2% and 10%, v/v in alcohol-water, 60:30, v/v), presenting a purple color against a slightly colored background. This TLC system is quantitatively evaluated in terms of stability of the color, precision, accuracy, and calibration. Activation is performed at 110 degrees C. Stability of the color of both analytes is reached after 12 min. Precision, less than 5%, is obtained at two levels. Good linearity is obtained in the range of 0.5-8 micro g for all analytes. Some applications show its utility in the quality control of capsules. The prederivatization technique, applying the described dipping reagent before development, reveals the presence of various reaction products, possibly isomers. These results prove that TLC can be a cheap and easy alternative for the analysis of AT and its lipophilic derivatives, AM and AE, as pure powder and in pharmaceutical-dosage forms.

Validation of an HPLC method on short columns to assay ketoconazole and formaldehyde in shampoo.

An HPLC method to determine simultaneously ketoconazole and formaldehyde in an anti-dandruff shampoo, originally developed on a long column, was transferred to two short columns with similar stationary phase properties, but with a length of at the most 30% of the initial one. Using the conventional column as reference, the fast HPLC methods on the short columns were validated. The validation characteristics consisted of selectivity, linearity range, precision (repeatability and time-different intermediate precision), bias and robustness. For the ketoconazole assay, linearity for peak area was found in the concentration range up to 0.20 mg/ml. For formaldehyde, two calibration ranges (0-10 x 10(-5) and 0-10 x 10(-4)%) were linear, both for peak area and height. The assays for both ketoconazole and formaldehyde in these ranges showed no bias and an acceptable precision, although the precision found with the short columns was slightly worse than with the long one. The robustness tests were performed applying a Plackett-Burman design. For the ketoconazole assay, 6 factors were examined in a 12 experiments design and for formaldehyde, 11 factors in 16 experiments. The methods were found to be robust. Despite the somewhat less good precision the transfer seems to be successful and the obtained assays on the short columns are applicable for fast routine analysis.

Physical and chemical evaluation of liposomes, containing artesunate.

As artesunate has a rapid onset of therapeutic effect and quick elimination, frequent administration is required, especially in the treatment of malaria. Such treatment courses led to bad patients' compliance, leading to high recrudescence rate. Therefore, slow release preparations seemed to be a logical approach in artesunate monotherapies, as can be developed with liposomal suspensions, especially for parenteral administration. Thus, the aim of this study was to develop sterile liposomes. The suspension was evaluated on its chemical/physical stability, including chemical degradation and crystallization of artesunate, and release capacities, by use of the dialysis technique. The maximal encapsulation degree of artesunate without crystals was 1.5 mg in 300 mg lipids per ml suspension, containing egg-phosphatidylcholine/cholesterol in a molar ratio of 4:3. The highest stability was obtained with a phosphate buffer of pH 5, which could be expected, as artesunate is almost totally encapsulated. But by reason of instability in water, the suspension containing artesunate 1 mg/ml was preferred, as the encapsulation efficiency is 100%. The in vitro release test proves that artesunate is reversibly encapsulated in liposomes. A method for sterile production of liposomes at lab-scale level is also presented.

Simultaneous determination of ketoconazole and formaldehyde in a shampoo: liquid chromatography method development and validation.

Ketoconazole is an antifungal agent, which is the active ingredient in a shampoo primarily used for the treatment of seborrhatic dermatitis (anti-dandruff shampoo). The shampoo also contains imidazolidinylurea as a formaldehyde releasing preservative. The aim of this study was to develop a HPLC system that allows the determination of both ketoconazole and formaldehyde. The finally selected isocratic system consisted of an Interchrom Nucleosil (250 X 4.6 mm, 5 microm) C8 column and a mobile phase containing acetonitrile-phosphate buffer 0.025 M, pH 4.0, 45/55 (v/v). Ketoconazole could immediately be determined at 250 nm after injection of diluted shampoo. Formaldehyde was measured at 345 nm after derivatisation with a 2,4-dinitrophenylhydrazine solution. At the selected conditions, the other excipients of the shampoo did not interfere in the assays for both substances. Method validation was performed on both assays. Different selectivity towards ketoconazole and formaldehyde was observed when applying other C8 columns. This fact, however, did not affect the assays of both substances.

Preparation of beta-artemether liposomes, their HPLC-UV evaluation and relevance for clearing recrudescent parasitaemia in Plasmodium chabaudi malaria-infected mice.

Egg phosphatidylcholine-cholesterol liposome formulations containing the antimalarial drug beta-artemether have been prepared and analyzed for their encapsulating capacity, chemical stability, leakage, in vitro release and their therapeutic efficiency against Plasmodium chabaudi infection. A HPLC-UV analysis of beta-artemether liposomes without derivatisation was achieved. A good linearity of y=4437.7 x+469.01 (R(2)=0.9999) with a detection limit of 2 microg ml(-1) was reached. Prior to this, liposomal formulations composed of different molar ratios of EPC-CHOL were prepared to select beta-artemether crystal-free liposome preparations. The formulation corresponding to 4:3 and a total concentration of 300 mg lipids ml(-1) buffer (pH 7.2), which could incorporate as much as 1.5 mg beta-artemether was selected for therapy. A trapping efficiency of nearly 100% was reached, the drug being located in the lipid bilayers. A dialysis test demonstrated that the drug could be reversibly released from the liposomes, reaching equilibrium within 24 h. After 3 months storage at 4 degrees C, no leakage of beta-artemether had occurred indicating a high stability of the liposomes. These liposomes were used to treat mice infected with the virulent rodent malaria parasite Plasmodium chabaudi chabaudi, with a 100% cure by clearing the recrudescent parasitaemia.

A comparison of the stage-specific efficacy of chloroquine, artemether and dioncophylline B against the rodent malaria parasite Plasmodium chabaudi chabaudi in vivo.

Chloroquine, artemether and dioncophylline B efficacy against Plasmodium chabaudi was compared. One intraperitoneal injection (10 mg/kg body weight) was given daily over 3 consecutive days to OF1 mice when they were predominantly bearing ring, trophozoite and schizont forms. The parasitaemia was monitored every 2 h during two schizogonic cycles and daily thereafter until parasites were cleared. Chloroquine was more efficient at the trophozoite stage, while artemether was effective against all erythrocytic stages, with a marked efficacy against the trophozoite stage. Chloroquine-treated and artemether-treated parasites displayed a pigment-clumping morphology and lowered the parasitaemia faster than dioncophylline B. Dioncophylline B was effective at trophozoite and schizont stages, but completely ineffective at the ring stage. These results demonstrate that a better timing of drug administration increases the efficacy of common and new antimalarial drugs and provides a model for antimalarial-action monitoring. Drug-induced changes in infected erythrocyte morphology are presented.