Stability of imipenem and cilastatin sodium in total parenteral nutrient solution.

The chemical stability and compatibility of imipenem-cilastatin sodium (Primaxin) in two different total parenteral nutrient (TPN) solutions was determined. TPN solutions consisted of 4.25% and 5% amino acids with 25% and 35% dextrose, respectively. Imipenem-cilastatin sodium was constituted with 10 ml of sterile water and admixed with 90 ml of TPN solution for a final concentration of 5 mg/ml of each drug. The final solutions were assayed at times 0 (immediately after admixture), 15 min, 30 min, 1, 4, 8, and 24 hr by a stability-indicating high-performance liquid chromatographic assay. Concurrently, test TPN solutions were monitored for pH changes, color changes, and precipitate formation. The potential effect of imipenem-cilastatin sodium on the stability of amino acids and other TPN additives was not evaluated. Imipenem and cilastatin sodium was stable (greater than or equal to 90% recovered) in each TPN solution at 15 min. A significant (greater than or equal to 10%) and steady decrease of imipenem recovery occurred at subsequent sampling times. Cilastatin appeared more stable than imipenem in both TPN solutions. A physical color change from colorless to dark orange appeared in each TPN solution over the 24-hr study period. Imipenem-cilastatin sodium is stable for 15 min in the TPN solutions studied; however, until the stability of the amino acids can be determined, the antibiotic should be administered through a separate line or Y-site while the TPN infusion is interrupted.

Improvement in potency assay of measles-mumps-rubella trivalent vaccine: interference between components and measures for its elimination.

In the potency assay of trivalent measles-mumps-rubella (MMR) vaccine by the immunocytochemical focus assay reported previously (Fukuda et al., 1987), development of rubella foci in RK13 cells was inhibited in the presence of a large excess of mumps component, resulting in an underestimation of the titre of the rubella component. When RK13 cells are infected with the mixture of mumps and rubella viruses, mumps virus interfered with the growth of rubella virus. Interference was mediated most likely by interferon induced by mumps virus. The interference was eliminated by a partial neutralization of mumps component by the addition of anti-mumps serum to the inoculum to RK13 cells. Improved method of potency assay of MMR vaccine incorporating the above measures and other modifications are described.

Urostomy appliances and stoma care routines. The relation to peristomal skin complications.

The aim of the study was to describe types of appliances and stoma care routines and evaluate their relation to peristomal skin complications. Sixty-six patients with a cutaneous uretero-ileostomy were interviewed and the peristomal skin was assessed according to Classification of Peristomal Skin (CPS). The results show a conservatism regarding the types of appliance and the stoma care routines. More than half of the patients used the same product at follow-up as they were initially fitted with three to 14 years earlier. The routines adopted by the patients were often inadequate, resulting in skin complications. Continuous exposure of the skin to urine by creation of a too wide opening in the face-plate and infrequent changing of the appliance resulted in development of pseudoverrucose skin lesions.

Feasible improvements in vaccines in the Expanded Programme on Immunization.

Feasible improvements in existing vaccines of the Expanded Programme on Immunization are reviewed. The toxicity of pertussis vaccines can probably be reduced and the immunogenicity increased by recently instituted improvements in purity and selectivity. Candidate vaccines containing inactivated pertussis toxin, with or without other components, are in use in Japan and in controlled trials elsewhere. Inactivated poliovirus vaccines have been improved over the past decade and presently show promise of inducing immunity with as few as two doses administered in infancy. At the same time, improved methods for delivering the oral poliovirus vaccine through mass vaccination campaigns are being increasingly employed throughout the developing world. Major improvements in the measles vaccine will probably come from the development of new stabilizers and the use of vaccines that are immunogenic in the presence of maternal antibody.

PIP: The toxicity of pertussis vaccines can probably be reduced and the immunogenicity increased by recent improvements in purity and selectivity. Inactivated poliovirus vaccines show promise of inducing immunity with 2 doses administered in infancy. The Expanded Program on Immunization (EPI) uses the diphtheria-tetanus-pertussis (DTP) vaccine, poliovirus vaccine, and measles virus vaccine. The incidence of serious toxicity (particularly screaming fits, attacks of pallor, or unusual behavior) and encephalitis is very low. A superior partially purified pertussis vaccine was developed by Sato that contained both the pertussis toxin and filamentous hemagglutinin. With the toxicity of purified-component vaccines reduced, the relevant pertussis antigens can be increased to the point where 2 doses will suffice. The present live oral polioviruses vaccine (OPV) and inactivated poliovirus vaccine (IPV) are prone to thermal instability and a cold chain may be a necessary component of immunization with live poliovirus vaccine in the near future. It was shown that 4th and 5th doses of OPV given at 4-week intervals after the 3rd dose elevated the proportion of infants who developed serum antibody to types 1, 2, and 3 antigen from 69%, 90%, and 76%, respectively, up to 83%, 96%, and 82%. DTP vaccine improved to 2 doses is adequate for initial coverage then full immunization for DPT, poliomyelitis, and measles at 3 and 9 months of age. Vero cells of a heteroploid karyotype and of an indefinite lifespan were used to develop a poliovirus vaccine, as they do not produce tumors in rodents. WHO and the US Food and Drug Administration accepted them as safe as cell substrates for certain purified viral vaccines. Measles virus vaccines also have thermal instability and immunogenicity. Thermal instability was greatly reduced with the introduction of buffered glycerol-sorbitol before lyophilization. Immunogenicity in the presence of maternally derived antibody while indicating successful immunization also indicates susceptibility to measles. In a trial of aerosolized vaccine in Mexican children of different ages using the Edmonston-Zagreb (E-Z) vaccine and the Edmonston-Swartz (E-S) vaccine, successful immunization was high even in 6-month-old infants with the E-Z strain but not with the E-S strain. Both OPV and IPV will continue in general use and improvements will come from more efficient delivery schemes, particularly pulse immunization.

Interference between strains in live virus vaccines, I: Combined vaccination with measles, mumps and rubella vaccine.

One to four different lots of four commercially available trivalent measles-mumps-rubella vaccines were tested for their efficacy as measured by the induction of antibodies to the three vaccine viruses. All of the products were satisfactory although a 100% seroconversion rate was attained regularly only with rubella vaccine. The live virus in the different measles and mumps vaccine components and especially the relative amounts of measles to mumps virus varied widely. Obviously, the efficacy of a vaccine should not be judged only by the virus content. Of main importance is the further adjustment of the dosage of the interfering vaccine virus strains in relation to their attenuation.

Determination of the epinephrine-refractory hypoglycaemic activity of whole-cell pertussis vaccine in mice.

A new assay method has been developed for the quantitative estimation of the inhibitory effect of pertussis vaccine on epinephrine-induced hyperglycaemia in mice. The statistical analysis of the assay was based on logarithm-transformed estimates of the blood glucose levels. The method was sufficiently sensitive to detect the activity of 0.004 millilitre of commercial combined diphtheria-tetanus-whole cell pertussis vaccine. The estimated common variance was as small as 0.0034 and the assay was highly reproducible. Among commercial vaccines there was a significant difference in activity. The activity of a stock pertussis vaccine was inactivated by 5 mM glutaraldehyde at 37 degrees C for 30 min, but resisted treatment with 40 mM formaldehyde at 37 degrees C for 5 days. The extent of inactivation with the chemicals was calculated by a parallel line assay as the activity relative to that of untreated control pertussis vaccine.

Interference between strains in live virus vaccines. II: Combined vaccination with varicella and measles-mumps-rubella vaccine.

A combined vaccine against varicella and measles-mumps-rubella made by mixing two commercially available products (Varilrix and Pluserix SK-RIT) has proved to be only partially successful in early trials. Although the seroconversion rates with the MMR components were comparable with those usually achieved, the varicella take was depressed to 77%. A new low dose measles-mumps-rubella vaccine was prepared in which the measles virus content was reduced to 1/5 and the mumps virus content to 1/8. Commercial varicella vaccine was added to the low dose MMR vaccine. The seroconversion rates for measles was 98.2%, for mumps 100%, for rubella 99.4% and for varicella 98%. This product seemed to be well balanced in respect of a possible interference between the four different virus vaccine strains.

Acellular pertussis vaccines: evaluation of reversion in a nude mouse model.

An animal model has been developed to assess the safety of acellular pertussis vaccines in terms of reversion to toxicity. Adsorbed pertussis toxoid preparations, alone or combined in a DTP formulation, were administered to nude mice intraperitoneally. In parallel, groups of positive and negative control mice received pertussis toxin and buffer, respectively. The circulating white blood cells of the animals were monitored for 28 days. Mice immunized with glutaraldehyde toxoid preparations did not develop a lymphocytosis during the observation period, whereas mice immunized with an experimental formalin pertussis toxoid vaccine exhibited a high lymphocytosis six days after vaccine administration, demonstrating, in this model, a reversion of the toxoid. The nude mouse model thus appears to reveal the in-vivo reversion of pertussis toxoids and could be included in the quality control panel for the assessment of the safety of acellular pertussis vaccine.

Clinical efficacy of a new, enhanced-potency, inactivated poliovirus vaccine.

The 1986-87 outbreak of paralytic poliomyelitis in Senegal, with 676 reported cases, provided an opportunity to evaluate the efficacy of an enhanced-potency inactivated poliovirus vaccine (N-IPV) in the Kolda region, where this vaccine has been used since 1980. 89 cases, confirmed to have poliomyelitis with residual paralysis, were enrolled in a case-control study, up to 5 matched controls being obtained for each case. The clinical efficacy for one dose of N-IPV was 36% (95% confidence interval 0%, 67%) and for two doses was 89% (95% CI 62%, 97%).

The reduction of animal usage by the application of indirect haemagglutination in the potency testing of diphtheria toxoid in combined vaccines.

Eight Adsorbed Diphtheria-Tetanus vaccines and 13 Diphtheria-Tetanus-Pertussis vaccines made by four different manufacturers were tested for the potency of the diphtheria components in guinea-pigs by the method of British Pharmacopoeia (1973). Two-hundred-and-ten guinea-pig sera consisting of ten sera related to each vaccine sample thus obtained were titrated for diphtheria antitoxin by indirect haemagglutination (IHA) and the conventional toxin neutralization (TN) tests. Statistical analysis of the results showed a good correlation between the titres obtained with the two tests. The potencies of the diphtheria components of various vaccines calculated from the antitoxin content of the respective guinea-pig sera titrated by the IHA test correlated significantly with the potencies obtained from the antitoxin content titrated by the routinely used TN test. The use of IHA in place of the TN test thus offers as an alternative that permits a reduction in animal usage.

[In vitro studies of pancreatic enzyme substitution]. / In-vitro-Untersuchungen zur Pankreasenzymsubstitution.

In-vitro activity of 14 commercial pancreatin preparations, commonly used in the Federal Republic of Germany, were tested. All had been declared by their manufacturers to contain more than 6000 FIP (Fédération International Pharmaceutique) units of lipase and to be acid resistant. The declared lipase and amylase amounts were found to be present in 11 of the 14 preparations. Three of the 14 preparations, said to be acid resistant were found not to be so in buffer with falling pH values between 4.0 and 2.5, so that there occurred an, at times marked, loss of enzyme activity. Most noticeable was the poor solubility of most preparations at pH 6.6. Only three of the 14 liberated their total enzyme content within 60 minutes, as they should for theoretical reasons, based on the relatively short duodeno-cecal transit time.

Immunocytochemical focus assay for potency determination of measles-mumps-rubella trivalent vaccine.

The immunocytochemically stained focus assay for the determination of potency of individual components in measles-mumps-rubella trivalent vaccine is described. The method involves the reaction of infected cultures maintained under the agar overlay medium sequentially with rabbit antiserum specific to each component, biotinylated anti-rabbit IgG serum, avidin-biotinylated-peroxidase complex, and substrate mixture. The potency of one component determined by the method was not influenced by the presence of two other components and was comparable to that determined by either dilution end point titration or plaque assay. The method offers a number of advantages over the current method based on neutralization of components other than the one to be titrated.

A comparison of combined diphtheria, tetanus and pertussis vaccines produced by different manufacturers, in laboratory animals and in infants.

Three DTP vaccines were investigated for potency and toxicity (reactogenicity) both in laboratory animals and in infants. Animal tests were carried out in conformity with the WHO recommendations. Three- to five-month-old infants were investigated for their specific antibody responses and for local and systemic vaccination reactions. No correlation was found between the potency values of the vaccines as expressed in IUs and the antibody titres of the vaccinated infants. The most striking difference between the human and animal responses to vaccination was observed in the case of the tetanus toxoid. The severity of the vaccination reactions in infants correlated with the toxicity of the vaccines as assessed in the mouse weight gain test (MWGT) carried out in CBA mice. No correlation was found, however when conventional or AKR mice were used in the MWGT.

Biomechanical optimization of a model particulate composite for orthopaedic applications.

Particulate composites are a potential solution to the need for an injectable, biocompatible, resorbable material that could be used to reinforce fractures and defects in bone and temporarily to stabilize porous ingrowth prostheses. We have developed a model system for producing and testing particulate composites to determine if mechanical properties suitable for orthopaedic applications can be achieved. The experiments used bovine cortical bone and various forms of hydroxyapatite for the particulate phase and a collagen and particulate reinforce gelatin-resorcinol-formaldehyde (G-R-F) adhesive for the matrix phase. Using unconfined compression testing, we measured the effects of variation in particulate type, size, shape, and volume fraction on the material properties of the particulate composites. We found that compressive strengths greater than 10 MPa and compressive moduli greater than 100 MPa could be achieved in this model system. Rough and irregular particulates exhibited higher compressive strengths and moduli than smooth and spherical particulates. Mechanical properties were largely independent of particulate size in the range of 125-850 microns diameter. This model system suggests that, with the development of new biocompatible matrix materials, particulate composites with mechanical properties suitable for orthopaedic applications can be achieved.

Studies on the minimal number of animals required to achieve assurance of satisfactory potency in diphtheria and tetanus vaccines.

The purpose of the potency test for adsorbed diphtheria and tetanus vaccines prescribed in the European Pharmacopoeia is to provide 97.5% assurance that the minimum requirement for potency is exceeded. In order to achieve this the use of at least six groups of sixteen guinea pigs or mice is prescribed. In some formulations, particularly of combined vaccines, the potency exceeds the minimum requirements by a very large margin and the numbers of animals used in the test appear to be unnecessarily large. Data are presented which show that 97.5% assurance of satisfactory potency can be consistently achieved with substantially smaller numbers of animals than are used at present. It is suggested that the prescription of large numbers of animals in routine issue tests for diphtheria and tetanus vaccines is unnecessary and inappropriate except in cases where the potency of the vaccine is in dispute.

Report of an informal meeting about alternative methods for the potency control of the diphtheria and tetanus components in vaccines.

On the 10th of December 1985 an informal meeting was organized at the National Institute of Public Health and Environmental Hygiene (RIVM) in Bilthoven to discuss the reduction of animals used in the potency control of the diphtheria and tetanus components in vaccines. The objectives of the meeting were to discuss alternative potency tests with some participants of the IABS-symposium on "Use and standardization of combined vaccines" and to make proposals for modifications in the WHO requirements. It has to be mentioned that the meeting was quite informal. The participants (Table I) continued the discussions which took place among a few of them in London 1985. Based on the discussions in London and Bilthoven there was an agreement on the following items.

[Experience of the People's Republic of Bulgaria in controlling diphtheria, tetanus and whooping cough]. / Opyt Narodnoi Respubliki Bolgarii v bor'be s difteriei, stolbniakom i kokliushem.

The analysis of the morbidity and mortality rates in diphtheria, tetanus and pertussis in Bulgaria after the introduction of the compulsory mass immunization of children with combined DPT vaccine is presented. These data indicate that morbidity in diphtheria, tetanus and pertussis has sharply decreased. Favorable results with respect to these three diseases are the consequence of the complete coverage of the child population by immunization with the vaccine whose quality has been steadily improving for the last 20 years. A higher purity of toxoids has been achieved, and at present it exceeds the latest WHO requirements. Pertussis vaccine is produced with the use of strains whose serological characteristics correspond to those of the pertussis strains circulating in the country. The study of the reactogenicity of DPT vaccine, carried out over the period of 20 years, has shown that the vaccine has low reactogenicity.

[Adhesive strength studies of biologic tissue adhesives]. / Klebefestigkeitsuntersuchungen an biologischen Gewebeklebern.

Different tissue adhesives including an own fibrin adhesive on the base of the human plasma fraction Cohn I were investigated in relation to their adhesive strength tension. These investigations were carried out on lyophilised skin grafts in vitro. The adhesive strengths were equal in case of the Cohn I adhesive, the Tissucol-Kit and also with Beriplast. These investigations will contribute to optimize an adhesive system.