How to photostabilize molsidomine tablets**This article is dedicated to the memory of Prof. Dr. K. Thoma

Different methods of photostabilization are presented for the very light sensitive molsidomine tablets. The incorporation of photostabilizers such as light absorber or pigments into the tablets considerably improved the photostability. Nevertheless, photodegradation was still detected after 12 h of intense light stress. Pigments are superior to colorants or ultraviolet absorbers. The use of titanium dioxide needs to be considered carefully. Preblending the pigment with the drug substance is very helpful for taking full advantage of its photostabilizing properties. Surface-treated titanium dioxide with reduced photocatalytic activity was less suitable than untreated. That was due to a change of particle agglomeration and adhesion behavior, which was demonstrated by scanning electron microscopy pictures. However, only the protection of the tablets by a cover, either by blistering or film coating, gave a photostable drug product.

ICH guideline for photostability testing: aspects and directions for use

The ICH guideline Q1B for photostability testing gives guidance on the basic testing protocol required to evaluate the light sensitivity and stability of new drugs and products. The choice of the irradiation method, although complying with the guideline demands, may effect test results. High irradiances may shorten testing times, but can lead to enforcement of photodegradation, which was demonstrated for molsidomine tablets. The exposure to an artificial light source (xenon lamp) was compared and correlated to natural daylight. Suitable testing methods for nifedipine and molsidomine tablets were developed. Deviating from the guideline recommendations, the presentation of powder samples should be done in tiny aluminium pans, facilitating the test procedure, minimising the risk of falsified test results due to improper sampling and improving reproducibility. When using glass dishes for the presentation of tablets to photostability testing, they should be lined by e. g. aluminium foil to avoid influences of light reflected from the sample tray.

Particular features of photolabile substances in tablets

Nifedipine and molsidomine tablets are extremely photolabile drug preparations, even at cool room light. Compared to solutions the light spectrum responsible for photodegradation is moved towards the long-wavelength range corresponding to the bathochromic shift of light absorption in the solid state. In the case of nifedipine tablets light up to 500 nm, especially the range between 400-420 nm, is degrading. Molsidomine tablets are affected only by ultraviolet light, but not by visible light. In both cases light penetrates less than 1 mm into the tablets. For nifedipine tablets the exact penetration depth could be determined due to the discolouration of the drug substance upon irradiation. It varied from 360 microm to 880 microm depending on the drug content. Since the decomposition products of nifedipine act as photostabilizers by spectral overlay, light penetration and photodegradation in nifedipine tablets are limited. The formation of gaseous and liquid decomposition products in molsidomine tablets enhances photodegradation. Changes of the tablet structure as well as dissolution and migration processes are discussed. Furthermore the degradation products donot photostabilize the drug substance due to the missing light absorption above 300 nm.

Influence of aqueous coatings on the stability of enteric coated pellets and tablets

Pancreatin pellets, placebo pellets and tablets containing vitamin B2 were coated with various aqueous and organic enteric polymers, HPMCAS, HP, Eudragit L 100-55, Eudragit L 30 D-55, CAP, CAT, CMEC and PVAP, comparatively investigated and tested for storage stability. With the exception of Eudragit L 100-55 and Eudragit L 30 D-55, higher amounts of coating material were needed to achieve gastro-resistance with aqueous coating than with organic coating. Film formation from aqueous dispersions of micronized HP 55 was affected by the degree of micronization and was improved by reducing the particle size of the polymer. Undercoating was another suitable measure to decrease the amount of coating material required. The choice of plasticizer was of special importance in the aqueous dispersions, and type and quantity must be appropriate for the polymer applied. Non-polymeric plasticizers such as triethyl citrate (TEC) evaporated along with water during the spraying or drying process and high temperatures promoted such losses. The moisture-sensitive pancreatic enzymes were damaged both by humidity and heat during aqueous coating. The extent of damage was dependent on the coating equipment used. Upon storage, coatings obtained from aqueous dispersions showed changes in enteric performance or release characteristics as a consequence of three chemical/physical mechanisms: hydrolysis of ester linkages in the polymer or plasticizer, evaporation of the plasticizer, delayed film formation. The active ingredient pancreatin induced hydrolysis of the ester based film-former hydroxypropyl methylcellulose acetate succinate (HPMCAS). However, even without the influence of enzymes, the phthalic ester groups of aqueous hydroxypropyl methylcellulose phthalate (HP) were partly cleaved after 11 months storage. In HPMCAS-coated pancreatin pellets, the plasticizer glyceryl triacetate was almost completely hydrolyzed by the enzymes, whilst triethyl citrate was lost by evaporation through permeable packaging material at elevated temperatures. Open storage at elevated temperatures and humidities caused changes in the surface structure of HPMCAS coatings, consisting of a smoothing of the originally somewhat porous film and sticking. When applied to vitamin B2 tablets, Eudragit L 100-55, Opadry enteric (PVAP) and Aqoat (HPMCAS) proved to be quite stable aqueous enteric coatings, whereas cellulose acetate phthalate CAP or cellulose acetate trimellitate CAT coatings as ammonia-neutralized aqueous solution or as water-based pseudolatex Aquateric were unstable when stored under stress conditions.

[Cooling action of topicals--present results and testing methods in vivo and in vitro]

The cooling effect of topicals has been used in the dermatological therapy as "physical effect" on the skin for more than hundred years. This effect of dermatologicals releasing free water is widely accepted, but current knowledge does not correspond to today's possibilities of experimental thermographic tests in man. The present paper describes the results published up to now and the current testing methods in vivo and in vitro.

Stabilization of dithranol in topical formulations

The influence of different factors such as drug concentration, temperature, pH value, humidity, solubility and stabilizers on the antipsoriatic drug dithranol in topical formulations has been investigated. Dithranol was examined in lipophilic, hydrophilic and cream bases under defined conditions. Additionally, stabilizers have been investigated to protect dithranol against degradation. The drug stability in the formulations was measured by a selective HPLC system. The results showed a strong dependency of the degradation on the drug concentration. The influence of temperature is not of the same importance. Besides the pH value also the type of puffer system must be considerated. The most important effect on dithranol stability which has been directed is the solubility of the drug substance in the ointment base. With higher solubility a significantly accelerated degradation occurs. Degradations of dithranol in hydrophilic and lipophilic bases can be reduced by different stabilizers. Among others succinic acid and tartaric acid being most effective.

Photostability of dithranol

The influence of light on the antipsoriatic drug dithranol was investigated. A Suntest CPS with xenon lamp and liquid cooling was used as light source for the test. Solutions of dithranol in different organic solvents and in therapeutical concentrations in excipients for the preparation of topical formulations were tested under defined conditions. The extent and rate of photodegradation was determined and compared with the degradation of light-protected solutions. The drug content in the solutions was measured by HPLC. Degradation products were characterised and identified by diode array technique and HPLC-mass spectrometry coupling. The results showed a strong dependency of the photodegradation on the excipient or solvent used.

Simultaneous quantification of released succinic acid and a weakly basic drug compound in dissolution media

A HPLC-method was developed to determine both fenoldopam, a weakly basic drug and succinic acid, a pH-adjuster for this drug in dissolution media. The usual assays for succinic acid were not applicable due to its low UV-absorption, the low pH-value of samples or the presence of buffer salts and fenoldopam. The described method is a simple non-ion-pair reversed phase HPLC-method using a fast scanning UV-detector and a PC software program for the quantification of both components. Succinic acid is detected at 205 nm and fenoldopam at 225 nm. The UV-spectrum is used to determine peak purity and to identify peaks (carried out at a 99.9% match). This is especially important as in some of the investigated samples an unknown peak elutes immediately after succinic acid, resulting in spurious high contents, if mistaken for succinic acid. The simple method accomplished the simultaneous quantification of both, succinic acid and fenoldopam, by an accurate, precise, specific and reproducible assay, with a linear range covering all concentrations relevant for dissolution testing. The method is stability indicating and can also be used for the quantification of fumaric acid, another pH-adjuster in dissolution media together with fenoldopam.

The pH-independent release of fenoldopam from pellets with insoluble film coats

Various ratios of succinic acid to fenoldopam mesylate, ranging from 0:1 to 18:1 were incorporated in pellets and coated with 1.5-12% w/w Surelease. Even though the coating level did influence the rate and amount of fenoldopam release, the influence of the succinic acid to drug ratio was much more important and evident at all coating levels. Being a weakly basic drug, fenoldopam release ceased when testing in SIF for succinic acid to drug ratios of 0:1-4:1, with the end of release being more abrupt for the 0:1 than for the 4:1 ratio. Only for a succinic acid to drug ratio of > or =5 was fenoldopam release constant for 6-8 h and independent of the pH-value of dissolution media. For a thin coat of about 2.5% w/w Surelease, those pellets showed an ideal controlled release behaviour with release rates of about 5-10%/h and a total release of almost 80% in 8 h. The dissolution profiles of Surelease coated pellets with high succinic acid to drug ratios (> or =5) and different coating levels, were evaluated for best fits to commonly used kinetic models. Sustained release mechanisms are discussed according to best fit models. The quantification of the pH-adjuster succinic acid, released from pellets with an acid to drug ratio of < or =1 showed, that despite their failure as a controlled release system for fenoldopam, the investigated coats could control the release of succinic acid effectively at optimized coating levels. For increasing succinic acid to drug ratios (< or =4) succinic acid was released at an ever more constant rate and release rates, though still faster than the release rates of fenoldopam, decreased steadily for increasing ratios. At a 5:1 ratio finally release rates of succinic acid and fenoldopam were almost identical. Therefore those pellet cores were almost completely emptied during dissolution testing, with both fenoldopam and succinic acid leaving at a constant rate and a total release of about 80% each for a 2.5% Surelease coat, while lower succinic acid to drug ratios had failed to show any sustained release for such thin Surelease coats. A similar formulation with fumaric acid instead of succinic acid failed to show the desired release pattern, indicating that it is the presence of a sufficiently high amount of succinic acid rather than the presence of an acidic compound in general, that ensures fenoldopam solubility at higher pH-values.

Investigations on the influence of the type of extruder for pelletization by extrusion-spheronization. I. Extrusion behavior of formulations

Three different extruders (the Alexanderwerk gravity feed roll extruder, the Gabler axial, single-screw extruder, and the NICA radial-screw extruder) were compared for their suitability for different placebo formulations and for fenoldopam pellets. A fourth extruder, the experimental ram extruder, was also included in some of the comparisons. Evaluation of the extrusion behavior of the three extruders showed differences as well as similarities among them, depending on the composition of the formulation. Although the NICA and Alexanderwerk units extruded all formulations successfully, the Gabler extruder failed to do so at a content of > 60% of soluble ingredients, such as lactose or mannitol. The extrudate surface improved for all extruders with an increase in water content of formulations, but was generally smoother for the Gabler than for the NICA or the Alexanderwerk units. A formulation with colloidal Avicel as spheronization aid showed an identical extrusion behavior for all of the investigated extruders. Of the three extruders, the Gabler unit showed the highest heat generation during extrusion, especially when extruding formulations with a low water content or high contents of soluble excipients. However, when the loss of water during extrusion or spheronization for various formulations was compared, only a two-way ANOVA test on the differences between the water content after extrusion and after spheronization showed a statistically significant difference between the Alexanderwerk or NICA and the Gabler extruder. The two-way ANOVA also proved that this difference is significant only for some formulations, e.g., lactose + Avicel PH 101 formulations, but not for Avicel PH 101 formulations.

Investigations on the influence of the type of extruder for pelletization by extrusion-spheronization. II. Sphere characteristics

Three different extruders, the Alexanderwerk gravity-feed roll extruder, the Gabler axial, single-screw extruder, and the NICA radial-screw extruder, were compared for their suitability for different placebo formulations and for fenoldopam pellets. A fourth extruder, the experimental ram extruder, was also included in some of the comparisons. The successful spheronization of extrudates from each of these extruders requires the correct water content. This water content, however, is different for each of the formulations and for each extruder. Generally, the Gabler unit required the highest amounts of water for a successful spheronization, yielding > or = 90% between 710 and 1250 microns. The NICA unit needed much less water for the same formulation, and the Alexanderwerk unit required even less water than the NICA unit. Pellet sphericity was also strongly dependent on the correct water content of formulations, but was generally better for pellets produced with the Alexanderwerk or NICA units. A two-way ANOVA test for the individual formulations showed a significant difference in the mean particle size of batches produced with the NICA or the Alexanderwerk and the Gabler extruder. No significant differences could be found between any of the Alexanderwerk or NICA batches. Both extruders showed a linear dependence of the mean particle size on the water content of formulations, but the Gabler extruder showed an almost unchanged particle size over a wide range of water contents, provided that the formulation could be extruded successfully. Batches that were extruded on the NICA unit showed a significantly lower bulk density than comparable Alexanderwerk or Gabler batches. Comparing the true density of pellets, we found that significant differences could only be stated for Avicel PH 101 + water batches and only for the NICA/Gabler interaction. True density increased for all three extruders with increasing amounts of soluble components and with increasing water content. The NICA batches also exhibited a significant difference of the Hausner factor from the other two extruders, but no differences could be found in the friability of pellets.

[The photostability of antimycotics. 3. Photostability of locally acting antimycotics]

The photochemical stability of a number of topical antimycotic drugs was tested. The light sensitivity decreases in the order naftifine, sulbentine, cloxiquin, tolnaftate and chlorphenesin. A liquid chromatography-mass spectrometry system was used to identify a number of photodegradation products. Light exposure of sulbentine leads to the formation of benzylisothiocyanate. Chlorphenesine solutions undergo photodehalogenation with the formation of varying photodegradation products depending on the solvent used. The photochemical reactions of naftifine are a cis-trans-isomerization and the formation of a dimer product. Drug preparations are also degraded under light exposure in a simulated topical application. Excipients in the drug preparations strongly influence the photodegradation kinetics and the chemical structure of photodegradation products.

[Photostability of antifungal agents. 2. Photostability of polyene antibiotics]

The polyene antibiotics amphotericin B, natamycin and nystatin are rapidly degraded under the influence of light. Amphotericin B as a heptaene has a markedly higher photostability than the tetraenes natamycin and nystatin. With a new HPLC method for the separation of the different polyene components we could perform a quantitative analysis of the photodegradation process. Initially degradation products with unchanged spectrophotometric absorption spectra are formed from each of the three polyene antibiotics. Longer light exposure leads to the subsequent degradation of the polyene structures. This photochemical instability was also detected in various drug products with polyene antibiotics as active ingredient. On direct sun exposure of topically applied polyene antibiotics a pronounced photodeactivation of the drug substances is expected.

Diabetes and nontraumatic lower extremity amputations. Incidence, risk factors, and prevention--a 12-year follow-up study in Nauru

OBJECTIVE

To measure the 12-year incidence (1982-1994) of nontraumatic lower extremity amputations (LEAs) in Nauruans, a population at high risk for NIDDM, and to determine the risk factors for amputation in Nauruans with diabetes.

RESEARCH DESIGN AND METHODS

Amputation data were abstracted from operating theater records in Nauru, hospital databases in Australia, and Nauru government records. Baseline characteristics of a cohort of 1,564 Nauruans aged > or = 20 years examined during a population-based survey in 1982 were used to determine risk factors for first LEAs.

RESULTS

Over this 12-year period, 46 first LEAs were performed on people with NIDDM, of whom 30 were members of the 1982 study cohort. The incidence of first LEAs in Nauruans aged > or = 25 years with NIDDM was 8.1 per 1,000 person-years in the study cohort and an estimated 7.6 per 1,000 person-years nationally. Amputations were associated significantly with lower BMI, lower blood pressure, higher fasting plasma glucose (FPG) level, and longer mean duration of diabetes at baseline, but levels of other risk factors, including cigarette smoking, plasma triglycerides, and plasma cholesterol, were also elevated in amputees. There were no amputations among individuals with baseline FPG levels < 7.8 mmol/l, irrespective of diabetes duration. FPG, baseline diabetes duration, and male sex were independent risk factors for first amputation using the Cox proportional hazards model. There was a decrease in the incidence of amputations after the commencement of a national foot care health education and prevention campaign in June 1992.

CONCLUSIONS

The incidence of LEAs in diabetic Nauruans was higher than in other populations after adjusting for age and duration. Given the apparent success of the Nauruan footcare program in reducing amputation rates, other populations with high rates of NIDDM and LEAs should consider population-wide prevention strategies.

Determination by interphase-FISH of the clonality of aberrant karyotypes in human hematopoietic neoplasias

Interphase-FISH (fluorescence in situ hybridization) studies have been devoted to the determination of clonality of aberrant karyotypes in human leukemia. Various levels of its extent have been examined, including the meaning of a single aberrant karyotype as representing a microclone, the use of FISH to confirm clonality in bi- or multiclonal leukemia, the estimation of the residual (aberrant) clone after contrasexual bone marrow transplantation, and the redetectability in interphase of the abl/bcr rearrangement. The quantitative findings of all these lines of interphase FISH analyses were based on the comparison with data from a large-scale "control" study on normal cells using the same DNA probes which have been chosen for the determination of clonality, i.e. centromeric DNA probes for chromosomes #1, #3, from #6 to #12, from #15 to #18, #20, X and Y, and a specific probe for the abl/bcr rearrangement. In addition, the validity of interphase-FISH analysis on classical bone marrow smears was examined. As a common outcome it was concluded that interphase-FISH technique is a valuable tool for defining clonality of karyotypic changes and, as a consequence, yields additional prognostic information in many human leukemias. It is recommended to perform interphase FISH in routine cytogenetics of leukemia, whenever reasonable.

Comparative interphase cytogenetics using FISH on human ovarian carcinomas

Analyses using fluorescence in situ hybridization (FISH) were performed on cytogenetic slides of 25 human ovarian carcinomas. Biotinylated alphoid DNA probes were used for the monocolor and bicolor detection of chromosomes #1, #7, #8, #11, #12, #17 and #20 in interphase nuclei of the target cell material. Specific loss of chromosomes #17 and #20 was the most significant finding in aberrant cell populations of the tumors, as was gain of chromosomes #7, #1, #8 and #11. By the use of probe combinations, the presence of combined gains and losses of several chromosomes within the same cell subpopulations could be shown in a series of tumors, while in others the significant numerical chromosome abnormalities found characterized various different cell populations. In summary, FISH could be shown to be a powerful tool of interphase cytogenetics, provided that its limitations are considered conscientiously.

[Relationships between manufacturing parameters and pharmaceutical-technological requirements of biodegradable microparticles. 2. Preparation of injectable microparticles in biodegradable polyester]

Local anesthetics containing biodegradable polyester microparticles are prepared using a modified solvent-evaporation process and a spray drying technique. The preparation methods are compared critically. The modified solvent-evaporation process is preferred for the preparation of microparticles. Yields of 90% and microparticle size distributions can be influenced in a reproducible manner. Using the spray drying technique yields are only 60%. The product is characterized by a high portion of microparticles under 10 microns, which are responsible for the rapid release of cinchocain in 168 h as well.

[The solubility kinetics of enteric-resistant tablets using riboflavin test tablets. 6. Pharmaceutic-technologic and analytic studies on gastric juice-resistant dosage forms]

To examine the dissolution kinetics of enteric coatings in vivo a test system with riboflavine was developed. This system allows to realize the beginning of disintegration in the small gut because riboflavine is excreted in urine already within 1 h after ingestion, and to locate the area of dissolution of the tablet in vivo, because riboflavine absorption is reduced in the great gut and colon. Thus the test system allows to examine and improve coating compositions in vivo and to demonstrate changes of drug dissolution in vivo conditioned by storage of enteric coated pharmaceuticals.

[Biodegradable gentamicin-depot implants made of beta-tricalcium phosphate ceramics. 3. In vivo studies on drug release, tissue tolerance, and biodegradation]

In vivo drug release properties and biocompatibility of gentamicin-loaded controlled release implants made of beta-tricalcium phosphate ceramics designed for the local antibiotic treatment of bone infections were investigated. Controlled release pellets containing 0.4 and 0.8 mg of gentamicin were implanted into the femoral bone of rats. Drug release was measured from renal excretion over a time period of 3 weeks. The excretion pattern can be described by an initial phase of increased drug release was faster at higher drug loading. Drug release from glyceride-containing controlled release pellets occurs at a significantly slower rate than from drug-loaded pellets without glycerides. Histological studies after implantation of the pure ceramic pellets and the controlled release pellets into the bone tissue of rats and rabbits are showing a high tissue tolerance and the biodegradability of the implants. However, the glyceride-containing pellets are degraded at a slower rate than the pure ceramic pellets.

Control of HBV and HDV infection in an isolated Pacific Island: 1. Pattern of infection

Hepatitis B virus (HBV) and hepatitis delta virus (HDV) infections are known to be hyperendemic in Nauru. Because of the consequences of chronic HBV infection, the Nauruan Government has commenced a program that aims to reduce and eventually eliminate hepatitis B infection by immunizing susceptible adults and children on the island and every newborn baby. At the outset of this program, a national seroepidemiological survey was undertaken. Eighty-eight percent of the population were tested, of whom 69.1% had markers of HBV infection. Evidence of superinfection with HDV was found in 22.7% of HBV carriers, with the highest prevalence in adolescents and young adults. All seronegative individuals were offered three doses of plasma derived hepatitis B vaccine. A post-vaccination survey of 64% of those vaccinated showed that 98% had developed circulating antibodies.

Mortality from diabetes in Nauru. Results of 4-yr follow-up

A population survey in 1982 confirmed that Nauruan adults suffer from an extremely high prevalence (24%) of non-insulin-dependent diabetes mellitus. A follow-up study of the survey subjects was conducted in 1986. The aim was to assess the burden of diabetes to Nauruans in terms of premature mortality. Age-adjusted mortality rates for diabetic subjects were significantly increased when compared with normal subjects (relative risks for 4-yr mortality were 4.53 in men, P less than .01, and 3.96 in women, P less than .05). Although there was an excess number of deaths among diabetic subjects compared with normal subjects and subjects with impaired glucose tolerance, there was no significant association between cause of death and diabetes.

Changing mortality patterns in Nauruans: an example of epidemiological transition

An analysis of mortality data for the years 1982-5 was carried out for the Micronesian population (aged 15 years and over) of the central Pacific Island, Nauru. Among males, the most common causes of death were circulatory system disorders (33.3%), accidents (25.2%), and diabetes mellitus (12.1%). The majority of accidents occurred in the 15-34 year age group and involved motor vehicles. Among females, neoplasms (almost all lung and cervix) (22.4%), circulatory system disorders (20.7%), and diabetes mellitus (17.2%) were the most common causes of death. When accidents are excluded, 59.4% of deaths were in persons with diabetes. Compared with Australia, mortality rates in almost all age groups were at least five times higher for males and females for a comparable period. Nauruan life expectancy (39.5 years for men and 48.5 years for women) is one of the lowest in the world. These data confirm the high mortality associated with diabetes mellitus in Nauruans as evidenced in earlier studies. Modernization of this society through the affluence acquired by the mining of phosphate has led to serious public health problems relating to non-communicable diseases so that the mortality trends now mirror those of developed societies.

[Resistance and disintegration behavior of gastric juice-resistant drug products. 3. Pharmaceutical-technological and analytical studies of gastric juice-resistant commercial preparations]

Enteric coated commercial dosage forms often do not correspond with acid resistance and disintegration requirements of the Ph. Eur. About 15-20% of 181 tested samples disintegrate during acid resistance test or do not disintegrate in buffer solution pH = 6.8. The percentage was extremely high amongst enteric coated pancreatin or cardiac glycosides (about 30%) preparations. Storage conditions and time influence acid resistance and disintegration time. 80% of 34 products coated with celluloseacetate phthalate, hydroxypropylmethylcellulose phthalate or polymethacrylic acid ester did not change disintegration time after 2 years storage at 20 degrees C. After storage at 40 degrees C the number decreased to 40%. After 5 years at 20 degrees C number of products which were not stable increased.

[Effect of film formers and plasticizers on the stability of resistance and disintegration behavior. 4. Pharmaceutical-technological and analytical studies of gastric juice-resistant commercial preparations]

Chemical an physical properties of film coating materials determine stability of enteric coated pharmaceutical dosage forms. About 80% of commercial enteric coated drugs with coatings of celluloseacetate phthalate or polymethacrylic acid ester did not change acid resistance or disintegration time after 2 years, storage at 20 degrees C or 40 degrees C. Disintegration time of 4 drugs which are enteric coated with hydroxypropylmethylcellulose phthalate, decreased more often. Some of these did not fulfill acid resistance requirements of the Ph. Eur., tests which show influence of softeners to stability of enteric coatings have to be extended.

[Thin layer chromatographic detection of emollients in gastric juice-resistant coatings. 2. The pharmaceutic technology and analysis of gastric juice-resistant dosage forms]

Softeners in enteric coatings as phthalic acid esters, citric acid esters, tartaric acid esters, glycerine esters, alcohols or surfactants can be identified by thin layer chromatography. Normally they are extracted by ether out of a phosphate buffer solution of the coating. In exceptional cases, it is necessary to extract dry isolated enteric coatings with acetone/ethanol. As developing solvents butanol and methylene-chloride are recommended. To separate similar substances as glycerine-diacetate from glycerine-triacetate it can be necessary to evaluate the results in both developing solvents. Softeners had been isolated and identified from 9 examples of commercial drugs.

Non-insulin-dependent diabetes in Nauruans: a comparison of newly and previously diagnosed cases

A comparison of 148 newly diagnosed ('incident') and 202 previously diagnosed ('prevalent') Nauruan diabetics, examined during a population survey in 1982, has permitted cautious inference regarding the natural history of non-insulin-dependent diabetes (NIDDM) in this Micronesian population. As might be expected the results of the comparison do suggest that Nauruan diabetics undergo further deterioration in glucose tolerance, subsequent to diagnosis of the disease. Plasma glucose concentration is higher in prevalent than incident cases (males: fasting--12.2 versus 10.4 mmol/l; 2 h--18.9 versus 16.3 mmol/l; and females: fasting--13.1 versus 9.3 mmol/l; 2 h--20.3 versus 15.8 mmol/l) suggesting that present treatment measures may not be effective in this population. There was also some evidence that the metabolic consequences of NIDDM may be greater in female than in male Nauruans. Apart from plasma glucose concentration, of 8 other biological variables examined by univariate and multiple logistic regression analysis, three showed consistent differences between incident and prevalent cases in females, but none were consistently different in males. A relatively small difference in estimates of obesity was observed between incident and prevalent cases, and this was particularly notable in males. A number of potential sources of bias in this study are highlighted, and definitive, longitudinal studies will be required to corroborate these findings.

Mortality patterns in the modernized Pacific Island nation of Nauru

Nauru is a small phosphate-rich independent island country situated in the Central Pacific. The population is Micronesian and was estimated to be 4,680 in mid-1981. An analysis of mortality data for the years 1976-81 indicates a high adult male mortality due to accidents, injuries, cardiovascular disease, and diabetes. The life expectancy estimate at birth for men was 49 years, and for women 62 years. The male life expectancy is among the lowest in the region. The considerable adult male mortality appears to be related to the rapidly acquired affluence and the ready availability of motorcycles, cars, imported foods, tobacco, and alcohol. The data suggest that modernization of the economy in Pacific Island nations can lead to new and serious public health problems.

The high prevalence of diabetes mellitus, impaired glucose tolerance and diabetic retinopathy in Nauru--the 1982 survey

A population survey in 1982 has confirmed that Nauruan adults suffer from an extremely high prevalence of Type 2 (noninsulin-dependent) diabetes mellitus. The crude population prevalence of Type 2 diabetes was 24%. Abnormal glucose tolerance (impaired glucose tolerance and diabetes) was present in over 40% of the adult population and exceeded 80% in both sexes after the age of 55 yr. Diabetic retinopathy was present in 24% of diabetic patients, confirming that this Micronesian population is susceptible to the microvascular consequences of hyperglycaemia. Subjects with impaired glucose tolerance had a prevalence of retinopathy three times that of normal subjects, though the difference did not reach statistical significance. Prevalence of retinopathy was substantially higher in diabetic patients than either normal subjects or those with impaired glucose tolerance.

[Amphiphilic drugs. 2. Relation between colloidal properties and pharmaceutic-technological, pharmacokinetic and pharmacodynamic behavior]

The physicochemical properties of amphiphilic drugs may affect the technological, pharmacokinetic and pharmacodynamic behaviours. Micelle formation of a drug is of considerable importance for its solubility, stability, adsorption pattern, mixed micelle formation and influences thus its pharmaceutical availability. The biological availability is in many cases decreased by interactions of a surface active drug with other substances before absorption, by altered diffusion behaviour and distribution properties. Colloidal association may also result in an alteration of pharmacodynamic effects. These relations depend on the fact, that discrete hydrophobic an hydrophilic parts in a molecule are also prerequisites for micelle formation and receptor interactions. Furthermore the high membrane affinity of these drugs is responsible for some therapeutic and toxic effects.

Genetics of diabetes in Nauru: effects of foreign admixture, HLA antigens and the insulin-gene-linked polymorphism

Genetic factors play a major role in predisposition to diabetes in the Micronesian population of Nauru. In people aged 60 years and older, 83% of full-blooded Nauruans were diabetic compared with 17% of those with ancestral foreign admixture, as detected by HLA typing. HLA distributions also showed a small increased risk for early onset of diabetes (less than 46 years) associated with HLA-Bw22 (Bw56). Variation in the restriction fragment length of DNA near the insulin gene was found, but was not associated with diabetes. The distribution in fragment lengths, previously reported in Caucasoids, was observed in healthy Polynesians, Melanesians and Micronesians.

The high incidence of diabetes mellitus in the micronesian population of Nauru

As a follow-up to surveys conducted three years ago among the Micronesian population of Nauru, the incidence and prevalence of diabetes mellitus was studied in 433 subjects aged 20 years and older. The diagnosis of diabetes was based on a 2-h plasma glucose of 200 mg/dl (11.1 mmol/l), enabling comparison with the Rochester, U.S.A., (Caucasian) and Pima (American Indian) studies. In both sexes the prevalence rate rose steadily with age, and the overall prevalence was 24% for both sexes. The overall incidence rate was 15.4 per 1,000 person-years. However, males had almost twice the incidence of the females (20.2% vs 11.5%). The incidence rate of diabetes in Nauruans was considerably higher than that found in Rochester and was second to that of the Pimas as the highest rate reported in the literature.