Biomedical subjects

S Rossi

Publications and source records attributed to S Rossi.

At least 217 records · Page 12Linked to original sources

PubMed1997

The combined use of ultrasound and densitometry in the prediction of vertebral fracture.

Measurement of ultrasonographic parameters provides information concerning not only bone density but also bone architecture. We investigated the usefulness of ultrasonographic parameters and bone mineral density for evaluating the probability of vertebral fracture. 397 postmenopausal women (59.1 +/- 6.0 years) with (n = 178) or without (n = 219) atraumatic vertebral fractures were studied. In all women, bone mineral density (BMD) of the lumbar spine was evaluated by dual X-ray absorptiometry (DXA) and speed of sound (SOS); broadband ultrasound attenuation (BUA) and Stiffness in the calcaneus were evaluated by an Achilles unit (Lunar Corporation). Ultrasonographic parameters and BMD were compared by examining the magnitude of the odds ratios, to determine which produces the highest estimate of the probability of odds of fracture, and by examining widths of the respective confidence intervals (CI) to show which estimate of odd ratio is the most precise. The relative risk of vertebral fracture, after adjusting for potential confounders, was 3.5 (CI 2.6-4.8) for BUA; 4.5 (CI 3.2-6.2) for SOS; 5.8 (CI 4.0-8.4) for Stiffness and 7.5 (CI 4.8-11.5) for BMD. Ultrasound (US) parameters were still significant independent predictors of vertebral fracture, even after adjusting for BMD. The relative risk of fracture for a simultaneous decrease by 1 SD of BMD and by 1 SD of each ultrasound parameter was 17.3 (CI 9.4-39.6) for BMD and SOS; 18.3 (CI 8.4-30.6) for BMD and BUA and 22.1 (CI 8.9-52.7) for BMD and Stiffness. Our data suggest that US and BMD provide complementary information which can be combined to improve estimates of vertebral fracture risk.

Age Factors↗

PubMed1997

Mortality of plastic-ware workers exposed to radiofrequencies.

The mortality experience of a cohort of Italian plastic-ware workers exposed to radiofrequency (RF)-electromagnetic fields generated by dielectric heat sealers was investigated. Follow-up extended from 1962 to 1992. The standardised mortality ratio (SMR) analysis was restricted to 481 women workers, representing 78% of the total person-years at risk. Mortality from malignant neoplasms was slightly elevated, and increased risks of leukemia and accidents were detected. The all-cancer SMR was higher among women employed in the sealing department, where exposure to RF occurred, than in the whole cohort. This study raises interest in a possible association between exposure to RF radiation and cancer risk. However, the study power was very small, and the possible confounding effects of exposure to solvents and vinyl chloride monomer (VCM) could not be ruled out. The hypothesis of an increased risk of cancer after radiofrequency exposure should be further explored by means of analytical studies characterised by adequate power and more accurate exposure assessment.

Adolescent↗

PubMed1997

Histological changes but not virus eradication reflect biochemical improvement in chronic hepatitis C patients showing a long-term response to interferon alpha therapy.

AIMS: To assess the relationship between changes in liver histology and virological parameters of HCV infection in patients with a sustained biochemical response to alpha-interferon treatment for chronic hepatitis, with the aim of identifying the most reliable indicator of treatment efficacy. METHODS: Quantitative serial testing of HCV-RNA in plasma samples collected on a monthly basis over the last period of post-treatment follow-up were tested in sixteen subjects with > or = 12 months aminotransferase normalisation following discontinuation of interferon therapy. The quantitative HCV-RNA determination in plasma was performed by a competitive reverse-transcription polymerase-chain reaction. Pretreatment and 12-month post-treatment liver histologies were blindly evaluated using a semi-quantitative scoring system. At these times a qualitative HCV-RNA analysis was also carried out. RESULTS: The post-treatment histological grading score was significantly reduced. Nevertheless, all patients except one tested positive for HCV-RNA in plasma (mean 1.7 x 10(6) molecules/ml): nine were positive in all the serial determinations, while the remaining 6 were intermittently positive. No relationship between genotype, viral load, pattern of viremia (intermittent or continuous) and change in histological score was found. CONCLUSIONS: Changes in liver histology are the most reliable indicator of the efficacy of interferon treatment in hepatitis C related liver disease. HCV-RNA clearance based on serial sampling does not appear to be a reliable indicator, even in the presence of a sustained biochemical response and histological improvement.

Adult↗

PubMed1997

Prognostic factors in thyroid carcinomas.

The AA review the so-called prognostic factors in thyroid carcinoma taking in consideration four of the five major histotypes of thyroid tumours: Papillary ca. (5-year-survival -91%), follicular ca. (73%), poorly differentiated ca. (48%) and undifferentiated ca. (0%), with an emphasis on papillary carcinoma. The prognostic factors are described in two major groups: Clinicopathologic factors comprising the classic clinicopathologic features--age, gender, size, extrathyroidal extension, vascular invasion, nodal metastization and distant metastization--and Biologic factors, comprising a group of heterogeneous and less classic features such as DNA content and proliferation markers, oncogenes and tumour-suppressor genes, growth factors and growth factor receptors, pro- and anti-apoptotic genes, mucin and histo-blood group antigens, cytoskeletal filaments, adhesion molecules, and so forth. Finally, the AA address briefly a third group of (prognostic) factors that reflect the interaction between the neoplastic cells and their microenvironment: extracellular matrix and proteolytic enzymes (laminin, collagen IV, fibronectin, collagenases, alpha-1 anti-trypsin) and lymphocytic infiltration (S-100 positive cells, IGF-I and IGF-I receptor).

Adenocarcinoma, Follicular↗

PubMed1996

Neuromagnetic study of movement-related changes in rhythmic brain activity.

Neuromagnetic fields from the left cerebral hemisphere of five healthy, right-handed subjects were investigated in a typical Bereitschaftspotential paradigm consisting of self-paced voluntary movement of the right index finger. To assess movement-related spectral changes of the spontaneous magnetoencephalogram. latency-dependent short-time spectra were obtained by Fourier analysis for each single trial. The number of trials in which the spectral estimate for a certain frequency and latency deviated from reference values was then transformed into a probabilistic relative power measure. A spectral power depression around 20 Hz was observed starting about 2.5 s before movement onset, followed by elevated power in the 20-35 Hz range starting about 500 ms after movement onset. Generally, the power increase differed from the prior depression in both spectrum and topography, suggesting different generating processes rather than just a 'rebound' effect of the idling rhythm generator. The time course and topography of spectral power changes are discussed in relation to the corresponding properties of the movement-related neuromagnetic fields (readiness field, motor field, and movement-evoked field I).

Adult↗

PubMed1996

Focal brain stimulation in healthy humans: motor maps changes following partial hand sensory deprivation.

Cortical motor maps of first dorsal interosseus (FDI), abductor digit minimi (ADM) and wrist flexors muscles were produced following transcranial focal magnetic stimulation of the contralateral motor areas in seven volunteers. Motor evoked potentials (MEPs) were recorded before and during median and radial nerves anaesthetic block at wrist. Results indicated that the FDI muscle cortical representation was significantly reduced; this muscle was entirely "enveloped' in the hand region deprived of its cutaneous sensory information, despite maintaining its usual proprioceptive feed-back and strength via the ulnar nerve. On the contrary, the ADM (serving as "control condition' because outside the anaesthetised hand area) cortical representation was unchanged, even if showing a tendency to enlarge in the topographic maps. No amplitude changes of compound muscle action potentials of ADM and FDI during peripheral stimulations were observed, while changes in F-wave responses were detected in both muscles. No significant topographic changes were found for the wrist flexors muscles. A possible explanation for these "short term' rearrangements of brain motor maps is given on the basis of neural plasticity mechanisms due to the loss of tonic cutaneous inputs on cortical and spinal motoneurons.

Anesthesia, General↗

PubMed1996

Changes in movement-related brain activity during transient deafferentation: a neuromagnetic study.

Neuromagnetic fields from the left cerebral hemisphere of three healthy, right-handed subjects were investigated preceding and during voluntary index finger movements performed every 8-15 s under two different experimental conditions: before (stage A) and during (stage B) anesthetic block of median and radial nerves at the wrist. The anesthesia caused blocking of cutaneous receptors and some of the proprioreceptors from a wide hand area, including the entire index finger. However, the index finger movements were not impaired because the muscles participating in the task were not anesthetized. The magnetic signals of the brain sources corresponding to the main components of the movement-related neuromagnetic fields (motor field, MF and movement-evoked field I, MEFI) were mapped and localized using a moving dipole model. In the three investigated subjects the MF and MEFI dipole sources were stronger (30% on average) during stage B than during stage A. No significant changes in spatial coordinates of the estimated dipole locations between stages A and B were observed. This was true for both MF and MEFI. The results show that the MEFI reflects not only proprioceptive input from the periphery but cutaneous inputs as well. In this way the results support the view that cutaneous inputs play a specific role in the cortical control of movement.

Action Potentials↗

PubMed1996

The role of cutaneous inputs during magnetic transcranial stimulation.

Latency and amplitude characteristics of motor evoked potentials (MEPs) from abductor digiti minimi (ADM) and first dorsal interosseus (FDI) muscles were evaluated in 7 healthy volunteers via magnetic transcranial stimulation of the hemiscalp overlying contralateral motor areas. MEPs in complete relaxation and during contraction were recorded in two different experimental conditions: before and following anesthesia of median (sensory + motor) and radial (sensory) nerve fibers at wrist. This procedure induced a complete loss of skin sensation from dorsal and palmar aspects of the hand area "enveloping" the FDI muscle. On the other hand, the skin overlying the ADM muscle, as well as the strength of ulnar nerve supplied muscles were spared. This selective sensory deprivation lead to the following short-term changes: the physiological latency "jump" toward shorter values in contracted MEPs vs. relaxation was partially lost in the FDI (3.0 +/- 1.4 ms in basal condition, 1.8 +/- 1.1 ms after anesthesia, P = 0.028), while it was still clearly evident in the ADM (3.7 +/- 0.9 ms and 3.3 +/- 1.0 ms, respectively). Moreover, minor amplitude changes of MEPs during active contraction in the two muscles were detected: MEPs recorded from the FDI muscle were less potentiated during voluntary contraction than those recorded from the ADM muscle. The role of the cutaneous input in governing latency/amplitude characteristics of MEPs is discussed.

Adult↗

PubMed1996

Structural, metabolic and ionic requirements for the uptake of L-carnitine by primary rat cortical cells.

L-Carnitine (L-C) is involved in the transport of acyl groups into mitochondria for beta-oxidation, although its role in the adult brain is still uncertain. We have shown before that the uptake of L-carnitine into cultured rat cortical neurones was dependent on temperature as well as the Na gradient and is inhibited by compounds resembling its structure, like gamma-aminobutyric acid (GABA), but most potently by specific GABA uptake blockers. In this study we have characterised this uptake process further. We have shown that the uptake of L-carnitine may be dependent on Cl ions, in addition to Na ions, but non on Ca ions. The L-C uptake was inhibited by substituent anions in the order gluconate (83%) > isethionate (32%), with propionate being ineffective, whereas GABA uptake was inhibited most potently by propionate substitution (79%) and equally by isethionate and gluconate (67%). This L-C uptake process was not affected by the amino acids, glutamine or lysine, up to 1 mM concentration, although beta-alanine at 500 microM caused a 38% inhibition. The uptake of L-C was also significantly inhibited by structurally-related compounds, with a carbon chain length of three to six atoms, possessing an amine group and/or a carboxyl group. At a concentration of 500 microM, 3-aminopropane sulphonic acid (53%), gamma-butyrobetaine (31%), gamma-hydroxybutyric acid (34%) and 4 methylaminobutyric acid (33%). Other compounds were effective only at the lower concentration of 10 microM, such as butyric acid (25%), nicotinic acid (26%), isonicotinic acid (26%), hexanoic acid (23%) and at 100 microM, like 6-aminocapric acid (22%). Drugs suggested to affect membrane properties, such as chlorpromazine, was without effect at 1 or 10 microM, whereas flunarizine (FLU) at 1 microM inhibited both L-C (24%) and GABA uptake (17%). Other drugs like the cholinesterase inhibitors, tacrine and eserine, also had a small inhibitory effect on L-C uptake, reducing it at 1 microM by 22 and 21% respectively, although higher concentrations were toxic (> 100 microM). Pretreatment of the cells with neuraminidase (50 U ml-1, 10 min) reduced the subsequent uptake of both L-C (18%) and GABA (42%). Hypoxia (3 h) also significantly attenuated L-C uptake (42%), however part of these effects were related to the loss of cell viability. In summary, L-C uptake occurs by a complex mechanism which at least in part may occur by a Na/Cl cotransport mechanism, which could be similar, to that of GABA or may even in part occur via the GABA transporter.

Amino Acids↗

PubMed1996

A neuromagnetic study of movement-related somatosensory gating in the human brain.

Neuromagnetic fields from the left cerebral hemisphere of five healthy, right-handed subjects were investigated under three different experimental conditions: (1) electrical stimulation of the right index finger (task S); (2) voluntary movement of the same finger (M); (3) M+S condition, consisting of voluntary movements of the right index finger triggering the electrical stimulus at the very beginning of the electromyogram. The three conditions were administered in random order every 5-8 s. In addition, the task somatosensory evoked fields (task SEFs) gathered during condition (1) were compared with control SEFs recorded at the beginning of the experiment during rest. In all subjects the overlay of somatosensory stimulation on movement provoked a decrement in brain responsiveness (gating) as determined by the amplitude of gated SEFs. The latter was found as the difference between the neuromagnetic fields during M+S condition (overlaying of movement and sensory stimulation) minus neuromagnetic fields under M condition (M only). The gating effect was found to begin approximately 30 ms after movement onset, and to last for the whole period of the ongoing movement. The theoretical locus of gating was estimated by dipole localisation of the difference between task SEFs and gated SEFS using a moving dipole model. The site of the "early" gating effect (< 40 ms) was found to be more anteriorly located than the "later" (> 40 ms) gating effect. The task SEFs were found to be larger (significant after 30 ms) than the control SEFs elicited under the basal condition. The results are discussed with respect to timing, mechanism (centrifugal and centripetal), locus and selectivity of gating. In addition, the results are discussed with regard to clinical application (measuring attentional deficits in patients with impairments of higher mental functions and measuring gating deficits in patients with disturbed sensorimotor integration.

Adult↗

PubMed1996

Ultrasound parameters in osteoporotic patients treated with salmon calcitonin: a longitudinal study.

Speed of sound (SOS) and broadband ultrasound attenuation (BUA) of ultrasound (US) in bone have been proposed as alternatives to radiation-based methods for the quantitative assessment of osteoporosis. However, the usefulness of US in monitoring response to treatment in osteoporotic patients has yet to be defined. To compare US with bone mineral density (BMD), we studied 112 osteoporotic women (age range 50-64 years). Seventy-eight of them were treated with salmon calcitonin nasal spray (CT; 200 IU/day, 1 month on and 1 month off) and calcium (500 mg/day); 34 patients were given only calcium. One hundred and four women complied with treatment throughout the 2-year study period. At baseline and after 1 and 2 years we measured BMD at lumbar spine by dual-energy X-ray absorptiometry (DXA), and SOS, BUA and Stiffness index, by an Achilles ultrasound unit. Moreover, biochemical markers of bone turnover (alkaline phosphatase, osteocalcin and hydroxyproline) were also measured at baseline and after 6, 12 and 24 months. In the calcitonin-treated group at the end of the study period BMD had increased by 1.99%, SOS by 0.20%, BUA by 0.88% and Stiffness by 2.12%. By contrast in the calcium-treated group all parameters had decreased (BMD, -2.66%; SOS, -0.55%; BUA, -3.30%; Stiffness, -6.0%) by the end of the study period. The differences between groups were significant for BMD, SOS and Stiffness. At baseline a significant, but weak correlation was found between BMD and US parameters. The correlation coefficients between percentage changes at the end of the study period, in BMD and in SOS, BUA and Stiffness, were all significant (p < 0.001), being 0.41, 0.53 and 0.57 respectively. In conclusion, ultrasound measurements carried out in conjunction with BMD measurements will yield a more comprehensive assessment of skeletal status and may be helpful in monitoring the response to treatment in osteoporotic patients.

Administration, Intranasal↗

PubMed1996

The Financial Impact of Laparoscopy versus Laparotomy in the Treatment of Uterine Leiomyomata

To compare the efficiency of two surgical techniques to remove uterine myomata, 120 premenopausal women were included in this case control study based on the criteria of no previous operations, size of leiomyoma, and age. Sixty patients were treated by laparoscopy (group 1) and 60 by laparotomy (group 2). The hospital stay for group 1 was shorter than that for group 2 (3.53 ± 1.33 and 7.98 ± 2.05 days, p <0.001). The rate of total complications (body temperature >38° C, hemoglobin <8.5 g/100 ml, infiltration of abdominal sutures, dysuria, reduction in blood platelets) was 13% in group 1 versus 53% in group 2 (p <0.001). The mean cost for each surgical treatment was $628.71 and $652.40, respectively. The mean entire cost (surgery plus hospital stay) was $1357.23 and $2298.90, respectively (p <0.001). The savings were detectable after 9 and 52 operations, respectively, whether including all expenditures or only the cost of surgery. The cost saving of the entire treatment for 60 operations was $56,500.12.

Journal Article↗

PubMed1996

Uterine Contractility in Patients with Endometriosis

Uterine contractility was evaluated in 30 women, 16 with endometriosis and 14 controls. Two catheters were introduced into the uterine cavity, one next to the fundus and the other in proximity of internal os. They were connected to a pressure transducer that transforms mechanical events into an electrical signal, and analyzed by a system dedicated to this purpose. Data were analyzed by unpaired Student's t and McNemar tests. Frequency and amplitude of oscillations and mean pressure uterine tone were evaluated. Frequency of oscillations in the fundus (mean ± SD) were significantly higher in women with endometriosis than in controls: 21.86 ± 9.75% at 10 minutes versus 10.20 ± 5.26%, respectively (p <0.04). The mean basal pressure tone was also higher than in controls: 55.54 ± 21.04 mm Hg and 25.28 ± 19.94 mm Hg, respectively (p <0.04). Abnormal uterine contractility in women with endometriosis may be associated with a possible tubal efflux of endometrial tissue and its ectopic implants.

Journal Article↗

PubMed1996

Financial impact in the Italian Health Service of laparoscopic versus laparotomic surgery for the treatment of ovarian cysts.

To assess the cost of two procedures for the removal of ovarian cysts, 200 pre-menopausal women were recruited for the surgical removal of ovarian cysts by laparoscopy (n = 100) and laparotomy (n = 100) according to case-control criteria. Patients operated by laparoscopy (mean age +/- SD 32.22 +/- 9.98 years) and laparotomy (mean age +/- SD 29.57 +/- 6.62 years) for ovarian cysts (mean diameters +/- SD 4.98 +/- 3.62 and 4.83 +/- 2.78 cm) had a post-surgical hospital stay of 3.12 +/- 0.41 and 7.25 +/- 1.08 days (P < 0.001) respectively. The total rate of complications occurring in patients operated by laparoscopy was 9 versus 53% (P < 0.001) of those operated by laparotomy; body temperature > 38 degrees C was recorded in 52/100 of patients operated by laparotomy versus 6/100 of those operated by laparoscopy. The mean cost for each pure surgical treatment performed by laparoscopy was US $498.17 versus US $642.47 when it was performed by laparotomy (P < 0.001). The laparoscopic surgical approach is more expensive in the first 36 operations, thereafter becoming cheaper. The mean of the entire overall expenditure was US $1142.08 and US $2138.72 for laparoscopy and laparotomy (P < 0.001) respectively. The entire expenditure for laparoscopy is higher than laparotomy only until eight operations. In conclusion, laparoscopy versus laparotomy has resulted in a saving of US $14,429.3 for 100 operations while the saving on entire costs was US $99,664.8.

Adult↗

PubMed1996

Serological alpha 1-antichymotrypsin in patients with probable senile dementia of Alzheimer type: a short-term longitudinal study.

Serum levels of alpha 1-antichymotrypsin (alpha 1-ACT), macroglobulin, alpha 1-antitrypsin, ceruloplasmin, acid glycoprotein, transferrin, and C-reactive protein were measured in patients with probable late onset dementia of Alzheimer type (I-AD), patients with vascular dementia (VD), healthy elderly (HC), and patients with chronic or acute inflammation. Three blood samples were taken at 10-15 day intervals. Serum alpha 1-ACT levels from first and second serum samples were elevated in one out of 11 I-AD patients. Serpin serum levels from the third sample were increased in four out of 11 I-AD patients. None of these patients showed increased levels of other acute phase proteins measured in the three serum samples. VD patients did not show abnormal serum levels of alpha 1-ACT. Serum levels of alpha 1-ACT along with those of other acute phase proteins were altered in patients with inflammation. This investigation showed that in I-AD patients with increased alpha 1-ACT and no concomitant elevation of other acute phase proteins, serum levels of alpha 1-ACT varied with time. Based on our results, serum alpha 1-ACT does not appear to be a useful biomarker for clinical diagnosis of probable I-AD, but it might be associated with the clinical history of the disease.

Acute-Phase Proteins↗

PubMed1996

Severe community-acquired pneumonia: a possible role for Chlamydia pneumoniae.

Between July 1992 and June 1993, 61 patients with severe community-acquired pneumonia were admitted to our semi-intensive care unit. For all patients chest X-ray, blood gas analysis while breathing room air, Gram stain and culture of bronchoaspirate, determination of acute and convalescent anti-body titers for Legionella pneumophila, Mycoplasma pneumoniae and Chlamydia pneumoniae, blood culture when body temperature was greater than 38 degrees C, and pharyngeal swab for C. pneumoniae detection by means of an indirect immunofluorescence test were obtained. Among the patients enrolled, 15 suffered from chronic obstructive pulmonary disease, 18 had serious chronic diseases, 9 were immunodeficient and 15 had cardiovascular diseases, and only 4 had no underlying disease. Etiologic diagnosis was reached in 30 cases (49%). As expected, due to the high rate of seriously ill patients, gram-negative pathogens were identified most commonly (15%), followed by Streptococcus pneumoniae (10%) and, surprisingly, by C. pneumoniae (10%). These data, showing the possible emergence of Pseudomonas aeruginosa and C. pneumoniae, warrant further studies in order to verify whether the epidemiological pattern of severe community-acquired pneumonia is actually changing.

Aged↗

PubMed1996

Percutaneous RF interstitial thermal ablation in the treatment of hepatic cancer.

OBJECTIVE: The aim of this study was to evaluate the usefulness of RF interstitial thermal ablation for treating hepatic cancer. SUBJECTS AND METHODS: Fifty patients, 39 who had 41 hepatocellular carcinoma nodules and 11 who had 13 hepatic metastatic nodules, underwent RF interstitial thermal ablation. In all but one, a thermal necrosis volume greater than the tumoral nodule volume was created to obtain total tumor destruction. One large tumor was treated for debulking purposes. RESULTS: Hepatocellular carcinoma nodule destruction was achieved in a mean of 3.3 sessions of RF interstitial thermal ablation. During a mean follow-up of 22.6 months (range, 3-66 months), 16 (41%) of 39 patients had recurrences; two (5%) of these patients showed local recurrences and the remaining 14 (36%) had new lesions. Nine of these 16 patients underwent further RF interstitial thermal ablation that proved effective. RF interstitial thermal ablation was also successfully repeated in four patients who had a second recurrence. With RF interstitial thermal ablation, we treated 54 hepatocellular carcinoma nodules in 39 patients. Eleven (28%) of the 39 patients died: five from hepatic failure due to advanced cancer and six from causes other than cancer. Autopsy was performed on three patients who died from causes other than cancer, one had had two new courses of RF interstitial thermal ablation for two new lesions. Gross examination failed to detect two treated tumor nodules; histologic examination of three other treated tumor nodules showed total necrosis in two nodules and a 3-mm focus of viable cancer cells in the other nodule. Cumulative survival curves showed the median survival time to be 44 months. The survival rate for the first year was 0.94, 0.86 for the second year, 0.68 for the third year, and 0.40 for the fourth and fifth years. In the patients treated for metastatic nodules, posttreatment imaging studies showed necrosis that varied from 80% to 100% in all cases. Pathologic studies performed on two patients who underwent surgery after RF interstitial thermal ablation showed 100% necrosis in one case and 80% necrosis in the other. CONCLUSION: RF interstitial thermal ablation is a useful percutaneous treatment for hepatic cancer.

Aged↗

PubMed1996

Dissolution enhancement of an insoluble drug by physical mixture with a superdisintegrant: optimization with a simplex lattice design.

The aim of the present work was to optimize a tablet formulation containing a physical mixture of a practically insoluble drug (prednisone) with a superdisintegrant (croscarmellose sodium) and two filler-binders characterized by differing water solubility (dicalcium phosphate dihydrate and anhydrous beta-lactose). Crushing strength, disintegration, and dissolution were measured for 10 formulations distributed over a factor space according to a simplex lattice design for a special cubic model. Multiple linear regression analysis was used to assess the best fit for each variable. The model predicted that increasing the amount of disintegrant to a critical amount (50%) would result in reduced disintegration time for dicalcium phosphate/beta-lactose ratios > 0.3, no changes in disintegration time for ratios < 0.3, and for all ratios an improvement in dissolution at 10 min. Crushing strength values of dicalcium phosphate increased with increasing disintegration concentration but not for beta-lactose tablets. The physical mixture of a practically insoluble drug with a superdisintegrant was confirmed as a valid approach to the improvement of dissolution, even in presence of other components. The solubility of the filler-binders influenced the minimum amount of disintegrant needed; when a soluble diluent was used, the amount of disintegrant required was reduced.

Anti-Inflammatory Agents↗