Many filters release particles and water-soluble materials when eluted with distilled water. Some filters tend to shed a proportion of the filter matrix (media migration ); membrane filters not previously rinsed sometimes shed a small amount of matrix, often cutting debris. Most membrane filters contain a nonionic detergent as a wetting agent, a plaslicizer such as glycerol, and a small amount of inorganic electrolyte (often calcium salts). The water-soluble organic solutes can be detected by reverse-phase thin layer chromatography and by isocratic reverse-phase high performance liquid chromatography. Solutes isolated by these two procedures are partially identified by UV or IR absorbance. Inorganic solutes are quantitated by atomic absorbance spectroscopy. With the possible exception of fibers released from depth filters, the extractables are harmless to mice and guinea pigs, but can interfere with analyses.
A method has been evaluated for non-destructive analysis of the gas headspace in ampuls. We determined with a Raman spectrometer the rotational spectra of the headspace gas in a series of ampuls purged with known O2/N2 mixtures, and the relative rotational scattering coefficients for O2 and N2 at atmospheric pressure. Calculated O2 concentrations were in excellent agreement with the known composition of the purge gases. The method is safe. sensitive, objective. universally applicable. and could be adapted to total-inspection quality control in automatic or semi-automatic industrial settings.
Phase transitions which occur in frozen antibiotic solutions were monitored with use of differential scanning calorimetry (DSC), microscopic analysis, scanning electron microscopy, and x-ray diffraction. It was shown three selected antibiotics all froze as the amorphous form and unless thermally treated before drying remained in the lessdesirable hygroscopic amorphous form. Conversion to the crystalline form at various sub-zero temperatures was determined; for cefazolin sodium, the conversion temperature was between –20 and –10 °C; for nafcillin, it was between –10 to –4 °C; and for cephalothin sodium, the thermal event was so slow that scanning rates as low as 0.625° per minute were too fast to detect its location by DSC. For the latter, crystallization was more effectively achieved by alternate means such as crystal seeding or by humidifying the freeze-dried material. From the DSC thermograms, phase diagrams were constructed and the phase changes identified. Such information is valuable in the design and control offreeze-drying cycles and also can permit the freeze-drying of products often believed to be poor candidates for the process.
An important factor affecting the recovery of biological indicators (BI’s) is the time elapsed between exposure to a sterilant and growth testing. The length of time and the temperature at which the BI’s are stored after sterilization were found to significantly affect growth. BI’s stored at 20–25 °C for 48 hr prior to testing showed a 90% reduction in growth when compared to those that had been refrigerated at 2–8 °Cfor the same time period. This was consistent for B. subtilis and B. stcarothermophilus spores and independent of the type of sterilization process studied.
In 1890 Altman dried pieces of frozen tissue by placing them in a vacuum desiccator at –20 °C. Since then the freeze drying technique has been constantly improved. In 1939 the freeze drying process was placed for the first time on an engineering basis, and 1940 saw the large-scale production of dried plasma for wartime use. The first book on freeze drying by Flosdorfin 1949 was followed by the first symposium on this subject held in London in 1952 and biennial courses initiated in 1958 by Rey in France. New advances were reported and stress was made to obtain uniformity and time reduction of the freeze drying cycles and a better understanding of the principles and basis which govern them. The ever increasing needs for freeze-dried products is demanding more basic and applied research in this technique and the future will no doubt see the development of equipment and systems which will allow freeze drying of a wide variety of products, in shorter cycles and at lower costs.
The review centers on chemical, chromatographic, and electrometric methods of oxygen analysis used in the study of parenteral solutions. Basic principles in each of the methods of analysis are presented along with indications of their sensitivities, advantages, and drawbacks. The past and current literature shows the Winkler method to be the bench mark for the development or modification of virtually any technique for dissolved oxygen measurements. Electrometric methods, most notably that using the membrane covered polarographic detector, appear to be the most promising in terms of generating rapid, accurate results.
Theoretical sphericity factors for objects of various geometric shapes were calculated based on ideal performance of a light blockage detector, an electrolyte displacement sensor, and an automatic image analyzer performing microscope oversize counts based on the horizontal projection of the objects. The sphericities calculated relate the dimension of these objects to the measurement required by the USP method, i.e., the longest effective linear dimension. Using as a mathematical model a suspension which at the 10-?m size contains five spheres, five cubes, 15 equants, five rods, 10 prolate ellipsoids, five flakes, and five fibers per milliliter, it is shown that while the hypothetical suspension would barely meet the USP requirement for large-volume parenterals, based on the longest dimension by manual microscopy, only about one-third of these particles would be detected using electrolyte displacement, about one-half would be accounted for by light blockage, and on the average the automated microscope would reveal almost three-fourths of the particles present. The use of correction factors to account for these discrepancies is suggested.
The availability of the probabilistic model of particulate inspection in sealed sterile containers, first reported in 1979 (/), potentiated both a study of human inspection capability and the rapid objective validation of a high speed, automated inspection system. The U.S. Pharmacopeia XIX implies a deterministic human particulate inspection standard. The data presented earlier and in the present paper demonstrate that the detection of particulates is probabilistic not deterministic. The resolution of the conflict between an invalid deterministic particulate inspection standard and a demonstrated probabilistic inspection is a prerequisite to the wider utilization of automated inspection devices. Specially addressed in this paper is the problem of data replicability in probabilistic validation trials. A demon-stration of the utility of 95% confidence limits for critical validation parameters is presented. The evaluation of detection probability for identified containers is the basis for relative determinations of both inspection security and discrimination. This methodology is equally applicable to the evaluation of comparative performance in an inspector group and to the validation of an automated device against the performance of selected inspectors. A brief overview of robotic inspection considerations is included.
This paper discusses the effect of pressure on the lyophilization, or vacuum freeze-drying. process, and the various types of vacuum gauges typically used for such pressure measurements. Location of the gauge on the process system, sterilization procedures, potential chemical contaminants, measurement dependence on gas composition, and other unique requirements of the freezedrying process on vacuum gauges are outlined. Of particular significance for freezedrying. the capacitance manometer gauge is discussed in greater detail, including theory of operation, construction, accuracy, and operation and calibration procedures. A comparison study is made of a capacitance manometer, a Hg McLeod gauge, and a thermocouple gauge on a commercial lyophilization system. When operated and calibrated properly, the capacitance manometer provides the accurate, repeatable pressure measurements that are prerequisite to successful lyophilization.
Mechanisms of heat transfer in lyophilization of parenteral solutions are discussed, with emphasis on conduction. Data are presented to demonstrate that the rate limiting resistance to conductive heat transfer is the gas phase resulting from lack of intimate contact between the heat source and the product. Experimental drying curves at constant shelf temperature and various constant chamber pressures reflect the dependence of thermal conductivity of this intervening gas phase, hence the drying rate, on pressure. Deduced values of the resistance of the gas phase at free molecular flow conditions agree with theoretical values. Increasing chamber pressure from 0.04 to 1.3 mm Hg at constant shelf temperature resulted in an increase of about 160% in the primary drying rate. The observed dependence of primary drying rate on pressure points to the need for control of chamber pressure in order to provide for optimum drying conditions and to insure reproducible freeze dry cycles.
Low temperature vacuum drying is an alternative to sterile dry filling as a formulation approach for certain ethanol soluble substances that are poorly soluble or unstable in aqueous media. To date this approach has been limited to formulations containing the drug per se. However, several substances appear suitable as excipients including urea, polyethylene glycol 4000, ascorbic acid, methylparaben, and propylparaben. Ascorbic acid appears to increase the stability of bruceantin, a novel plant product that exhibits antitumor activity.
Although the sensitivity of the Limulus Amebocyte Lysate (LAL) Test for gram-negative endotoxin is well established, several reports have appeared in the literature indicating that substances other than endotoxin can elicit positive LAL test reactions under certain conditions. This discussion of LAL test specificity deals with the impact these findings could have on the use of LAL for pyrogen testing in the parenteral drug industry, and concludes that false positive LAL test reactions due to substances other than endotoxin need not concern most parenteral drug manufacturers. These, however, can be ruled out by using appropriate controls.
Tunnel sterilizers are being applied increasingly for the continuous sterilization and depyrogenation of glass containers used for parenteral medications. They impose validation parameters quite different from batch sterilizers. This study delineates a program and the results obtained in the validation of an infrared tunnel, encompassing thermal consistency and reproducibility, heat penetration of different-sized glass containers, measurement of air and container particulate matter, microbial lethality, and pyrogen destruction measured with the Limulus Amebocyte Lysate test.
A procedure to permit objective comparison and thus validation of alternate particulate inspection techniques has been developed and is described. This procedure is based upon the finding that particulate inspection methodologies, human and robotic, are probabilistic rather than deterministic in nature. This is due in major part to the size and contrast of the particulate contamination encountered. Two criteria are utilized for particulate inspection evaluation: (a) the efficiency of rejection of the containers to satisfy CMP requirements: and (b) the economic effectiveness of the inspection in terms of labor and falsely rejected good material. The effect of a probabilistic inspection on the nominal batch quality and the repticability of the quality assurance sampling inspection are also discussed. A tentative conclusion is reached that a deterministic sampling inspection is unduly responsive to minimal particulates and should be more sensitive to the low concentrations of major particulates encountered. A self-contained step-by-step guide to the use of the described procedure for validation of new techniques or instruments is included in an Appendix.
Recent FDA inspections of ethylene oxide sterilization facilities have revealed that many medical products labeled as sterile are processed without a properly validated sterilization cycle. Since there is no clear definition as to what ethylene oxide sterilization qualification/validation entails, this study is an attempt to clarify the meanings of these terms. The difficulty in arriving at the “maximum/minimum” conditions in an ethylene oxide sterilizer is examined. A comparison is made to the use of the Stumbo equation as a measurement of the sterilization effectiveness delivered to the product. The 3-dimensional Cartesian co-ordinate is introduced as a means of defining the loading pattern and the location with the “minimum” conditions for the placement of innoculated products and/or biological indicators. Graphical presentation of the trajectories of the key process parameters is used to illustrate the importance of validation studies prior to making production runs.
The purpose of this study was to quantify for the first time the size and concentration of particles that can be detected by visual inspection. Five-milliliter ampuls with known concentrations and sizes of polystyrene beads from 5 to 40 μm suspended in electrolyte solution were inspected by trained student inspectors using 15-sec pacing. Particle size was the most significant variable in the ability to detect particle contamination. A 50% probability exists for the inspectors to reject 20-μm particles. It was concluded that such a rejection rate be achieved with 20-μm particles in order for inspectors to qualify for in-line inspection.
Ethylene oxide gas (EO) is shown to affect Bacillus subtilis spore outgrowth kinetics without detectably affecting germination kinetics. Outgrowth of EOtreated spores is delayed up to 18 hr. The delay is not the result of an alteration in the exponential growth rate of the resulting vegetative cell population. Post-process B. subtilis biological indicators (BI’s) utilizing paper carriers, retain detectable residual EO levels for at least 48 hr. The data indicate that these levels are absorbed to the spores. Consequently. small EO residual levels potentially have significant biological consequences. As a result of the evidence of EO spore injury and retained EO residual levels, it is important that EO, BI recovery systems must be designed with meticulous care. Specific considerations for the design of a BI recovery system are outlined.
In 1975 the USP test for assessing the efficacy of preservatives was modified. Of major significance was the change in the temperature at which the killing rate was assessed (from 32 °C to the storage temperature specified on the label, or at 20 to 25 °C if no storage temperature is specified). For most of Connaught’s products the specified storage temperature is 2–8 °C. After July 1, 1975 all microbiological efficacy testing was performed on inoculated samples that were stored at about 4 °C. The results are presented as days required to attain at least 99.9% reduction in the number of viable lest organisms in the inoculated samples and indicate that preservative efficacy decreases when storage temperature is lowered from 32 to 4 °C. In two products the preservative was found not satisfactory when tested by the USP XIX method and a change of preservative was recommended.
A Collaborative Study, initiated under the auspices of the Health Industry Manufacturers Association, was designed to determine a level of a reference endotoxin that could be considered pyrogenic in a cross section of rabbit colonies used for USP pyrogen testing. This study was designed to establish, in a definitive way, a reference level against which the Limulus Amebocyte Lysate Test(LAL) could be standardized. Since the LAL test is much more sensitive than the rabbit test in the detection of pyrogens, its equivalency to the rabbit test has to be measured with a pass/fail level that has some relationship with the level of pyrogen that is considered pyrogenic in the rabbit. The Collaborative Study establ;ished with 95% confidence that a staistically avrage laboratory wsill attain 50% pass/fail results at some concentration level above 0.098 ng/ml of Difco E. coli 055:B5 endotoxin (Lipopolysaccharide B). It is recommended that 0.1 ng/ml be set as the standard reference pyrogenic activity against which the Limulus Amebocyte Lysate Test (LAL) is to be compared. If an LAL test can be performed to demonstrate a test failure rate significantly greater than 50% at 0.1 ng/ml of Difco E. coli 055:B5 endotoxin, that test will be considered qualified for use under the conditions opf evaluation as equivalent to the USP rabbit test.
