Safety in the preparation of cytotoxic drugs: How to integrate gravimetric control in the quality assurance policy?

PURPOSE: We present the way to integrate gravimetric control (GC) in a centralized preparation of cytotoxic drugs unit. Two different modalities are described. In the first strategy, the balance is located inside the isolator, whereas in the second, it is located outside in order to remove many technical and ergonomic constraints. These two modalities are compared in terms of benefits and limits. METHODS: GC consists in comparing the observed weight variation with the expected weight variation using a precision balance. According to the B-in strategy, this variation is directly attributable to the weight of the cytotoxic solution injected, whereas with the B-out strategy, the weight of various additional components must be taken into account. RESULTS: Five hundred and seventy-seven preparations have been weighed. For "B-in" strategy, the 95% confidence interval is [1.02-1.14%] and every preparation is below the threshold of 5%. For "B-out" strategy, the 95% confidence interval is [2.34-2.63%] and 94% of preparations are below the threshold of 5%. B-in strategy is distinctly more precise than B-out strategy and can be applied to all preparations. However, B-out strategy is a feasible option in practice and enables the detection of an important mistake. All in all, results obtained from B-out strategy can be considered as a quality indicator in the production line. CONCLUSION: Results of GC are helpful in the final step of release, which the pharmacist is responsible for. Many contributions in the quality assurance policy could justify using of GC in every unit.

Optimization of a model of red blood cells for the study of anti-oxidant drugs, in terms of concentration of oxidant and phosphate buffer.

The aggression of erythrocytes by an oxidative stress induces hemolysis. This paper aims to valid a model of erythrocytes in terms of composition of the phosphate buffer solution and of concentration of a well-known oxidant, AAPH. Three compositions of phosphate buffer solution are mixed with three concentrations of oxidant. The influence of these two parameters on hemolysis is independently studied by a variance analysis and a Kruskal-Wallis test when ANOVA is not available. The hemolysis rate increases with time at fixed oxidant concentration, but is not influenced by the composition of the buffer solution. The highest hemolysis rate, 90%, was only measured within 2 h with the highest oxidant concentration. If we retain this concentration of oxidant, the lower concentration of the buffer can by eliminated by a significant less hemolysis and the highest concentration of the buffer can by chosen in regard of the better precision for a similar hemolysis compared to the mean buffer. We hope to study the effect of anti-oxidant agent with such a model of erythrocytes.

Study of morphology of reactive dissolution interface using fractal geometry.

The determination of reactive fractal dimension was carried out using two forms of the Noyes-Whitney equation, -dQ/dt = K(Q/Q0)DR/3 and -dQ/dt = K'RDR-3 using the Richardson plot on the basis of previous data obtained by dissolution of an orthoboric acid powder. The correlation of the results provided by the two ways of calculation allows proposal of the hypothesis that dissolution begins on a specific population of reactive sites and probably promotes the formation of microporous volumes or cracks.

Accuracy of urine output measurement with regular disposable nappies.

Evaporation of urine from four types of disposable absorbent infant nappies (A, B, C, D) was assessed under a radiant warmer or in an incubator, with or without phototherapy. Each nappy was weighed dry and then 5, 10, 15 or 30 ml of urine were added. The nappy was immediately reweighed, placed in its study environment and then weighed 5, 15, 30, 60 and 120 min later. Under all conditions, the percentage evaporation from each type of nappy increased during the 120 min and was inversely correlated with urine volume. Without phototherapy, the maximum evaporation at 120 min with a 5-ml urine sample was 15.9% +/- 6.1% for nappy B in the incubator and 20.8% +/- 4.0% for nappy A in the radiant warmer. Phototherapy was associated with slight but significant changes in evaporation in the incubator and the radiant warmer. Nappy D allowed the lowest percentage evaporation in the incubator with or without phototherapy and in the radiant warmer with phototherapy (8.8% +/- 4.4%, 2.4% +/- 1.8% and 16.0% +/- 10%, respectively for a 5-ml urine sample).

[Identification and evaluation of free radicals in the sequence cardiac ischemia-reperfusion]. / Identification et évaluation des radicaux libres dans la séquence ischémie-reperfusion cardiaque.

The role of free radicals (FR) has been suggested in the development of ischaemia-induced myocardial reperfusion. When the equilibrium between the cellular sources and defense system is disturbed, FR may react with cellular components and produce a number of lesions. In general, the action of FR is shown indirectly by studying the effects of substances interfering with the production or the elimination of FR or of systems which produce FR on the physiopathological consequences of ischaemia and reperfusion. A physico-chemical technique, Electronic Paramagnetic Resonance (EPR) has been used in biology. The high reactivity and the very short life span of several types of FR pose methodological problems. A "stabilisation" of FR may be obtained by spin-trapping, a technique which consists of adding a diamagnetic substance to the reaction which forms covalent bonds with FR and forms a stable, detectable radical product. This technique has enabled identification and evaluation of FR liberated in the perfusion fluid of isolated perfused rat hearts and to determine the importance of the different mechanisms of production.

[The medicinal leech Hirudo medicinalis: clinical use of the animal and therapeutic prospects of hirudin]. / La sangsue Hirudo medicinalis: utilisations cliniques de l'animal et perspectives thérapeutiques de l'hirudine.

Blood sucking leech, Hirudo medicinalis, used in Medicine for very long, knew an intensive employment during early 18e century but its excess was responsible of the temporary disparition of the animal from the therapeutics. Leech has currently recovered a clinical use, especially in microsurgery. On the other hand, hirudin, main active compound isolated from leech extract and also known and used for long, offers interesting outlooks by its anticoagulant and antithrombic properties. This explains the great interest of hirudin preparation by molecular genetics.

Protective effect of sucrose on spray drying of oxyhemoglobin.

As far as we know, spray drying has previously not been applied to oxyhemoglobin, undoubtedly because of the sensitivity of oxyhemoglobin to temperature and oxidation. Our experience with freeze drying encouraged us to perform spray-drying trials in order to compare the results of the two methods, in the absence and the presence of protective compounds. Spray drying of hemoglobin without a protective compound led, as in freeze drying, to formation of a percentage of methemoglobin (50%) that makes it unsuitable for transporting oxygen. In the presence of 0.25 M sucrose (optimum) and at 80-100 degrees C, the functional properties of the hemoglobin were well preserved (methemoglobin approximately 4%), and the residual humidity was limited to approximately 3%. Structural investigation by optical circular dichroism confirmed the results obtained by freeze drying: in the presence of an effective protector, the spectra were similar to those of control hemoglobin and the immediate environment of the heme did not undergo any major change. Electron spin resonance absorption bands in all samples were similar for each value of the spectral decomposition factor, g. This suggests that the structure of the heme is not altered by desiccation and that the protector does not penetrate into the heme pocket since it would have disturbed the symmetry of the crystalline field. Fundamentally, these results are equivalent or similar to those observed with freeze drying; since spray drying is a different process of dehydration, the results indicate a lack of specificity in the phenomena of oxidation or of protection affecting hemoglobin.

Problems of haemoglobin freeze-drying: evidence that water removal is the key to iron oxidation.

Formation of methaemoglobin during freeze-drying of oxyhaemoglobin raises the question of the cause and mechanism of the oxidation. Haemoglobin with or without lyoprotector (250 mM glucose or amino acid salt) has been subjected to freeze drying changes in either or both of two constraints--vacuum and rise in temperature. A rise in temperature from -40 to +10 degrees C had no substantial denaturing effect on haemoglobin whether protected or not. Maintenance of a vacuum over frozen haemoglobin for 18 h often produced subtotal desiccation. Unprotected haemoglobin was partially oxidized (39% MetHb) whereas protected haemoglobin was not (less than 4% MetHb). Haemoglobin was also dried by rapid dehydration of thin films in a stream of air at room temperature (20 degrees C). The methaemoglobin content was then 43% whereas the amino acid salt or glucose limited it at 4 and 7%, respectively. Haemoglobin is oxidized, therefore, only because of the removal of water. Protectors, not specific in structure and action, probably work by holding or reinforcing the critical number of hydration layers around haemoglobin.

Influence of physical conditions on the oxidation of hemoglobin during freeze-drying.

The potential influence of some physical conditions--dialysis, crystallization, concentration, pH, and temperature--on the amount of methemoglobin obtained after freeze-drying of hemoglobin has been studied. Among these parameters, pH and crystallization influence the oxidation. In acid medium (pH 5), the oxygen saturation is better than that obtained for pH 8. Crystalline hemoglobin leads to a methemoglobin rate significantly lower (29% versus 49%) than untreated hemoglobin. Methemoglobin is continuously formed during desiccation even at the lowest temperature. Although it has been possible to lessen the denaturation of hemoglobin by the choice of a definite preliminary treatment of the samples, we were not able to reduce methemoglobin to low and physiological values. However, the results obtained with crystalline hemoglobin make it possible to propose mechanisms for the oxidation of the hemoprotein.

Freeze-drying of hemoglobin solutions without adjuvant and in presence of glucose, tris, and beta-alanine: a study by electron spin resonance of the oxidized compounds produced.

Hemoglobin cannot be freeze-dried without the presence of protective compounds. Carbohydrates are a well-known example of such compounds, but we have shown that some amine buffer and amino acids are also very effective. The mechanism of action of all these molecules is unknown. We report here experimental data showing that the protective effect is not the result of a direct bond between iron and the protective compound added.