Modeling and comparison of dissolution profiles

Over recent years, drug release/dissolution from solid pharmaceutical dosage forms has been the subject of intense and profitable scientific developments. Whenever a new solid dosage form is developed or produced, it is necessary to ensure that drug dissolution occurs in an appropriate manner. The pharmaceutical industry and the registration authorities do focus, nowadays, on drug dissolution studies. The quantitative analysis of the values obtained in dissolution/release tests is easier when mathematical formulas that express the dissolution results as a function of some of the dosage forms characteristics are used. In some cases, these mathematic models are derived from the theoretical analysis of the occurring process. In most of the cases the theoretical concept does not exist and some empirical equations have proved to be more appropriate. Drug dissolution from solid dosage forms has been described by kinetic models in which the dissolved amount of drug (Q) is a function of the test time, t or Q=f(t). Some analytical definitions of the Q(t) function are commonly used, such as zero order, first order, Hixson-Crowell, Weibull, Higuchi, Baker-Lonsdale, Korsmeyer-Peppas and Hopfenberg models. Other release parameters, such as dissolution time (tx%), assay time (tx min), dissolution efficacy (ED), difference factor (f1), similarity factor (f2) and Rescigno index (xi1 and xi2) can be used to characterize drug dissolution/release profiles.

The use of an artificial urinary sphincter in women with type III incontinence and a negative Marshall test

PURPOSE

We evaluate the efficacy of the AMS 800 artificial urinary sphincter in women with type III incontinence.

MATERIALS AND METHODS

We enrolled 207 women with genuine stress incontinence due to intrinsic sphincter deficiency. Primary inclusion criterion was a negative Marshall test. A modified surgical procedure was used to implant the AMS 800 through an abdominal approach, with placement of the cuff around the bladder neck between the periurethral fascia and vagina. Followup data were available for 206 women, including 179 with nonneurogenic and 27 with neurogenic bladders (mean followup 3.9 years).

RESULTS

There were 12 (5.9%) explantations due to the prosthesis either through an erosion, extrusion or both that were necessary. The only significant risk factor for explantation was perioperative injury. This injury resulted in 8 explantations in 49 patients compared with 4 in 155 who did not have such injuries (p = 0.0016). Of the 190 patients with working devices continence was achieved in 88.7% (49 of 168) and 81.8% (18 of 22) of those with nonneurogenic and neurogenic bladders, respectively. Social continence (slight leakage but no pad use) was reported by 7.7% (13 of 168) and 9.1% (2 of 22) of patients in the nonneurogenic and neurogenic groups, respectively. The remaining patients reported leakage and pad use.

CONCLUSIONS

The AMS 800 can be used successfully to treat women with genuine stress incontinence due to intrinsic sphincter deficiency. The modified surgical approach resulted in fewer perioperative injuries and, consequently, a low explantation rate. Women with genuine stress incontinence, a low urethral closure pressure and negative Marshall test indicating severe intrinsic sphincter deficiency are potential candidates for artificial urinary sphincter implantation.

Quality of life in spinal cord injury patients with urinary difficulties. Development and validation of qualiveen

BACKGROUND

Quality of life (QoL) may be severely affected in patients with spinal cord injury (SCI) and resulting urinary difficulties (UD). There is, however, a need for instruments capable of measuring QoL in these patients. The aim of this study was to develop and validate a questionnaire suitable for use in SCI patients with urinary disorders.

METHODS

Following patient interviews, a questionnaire was developed in French that was subjected to item reduction and cross-sectional validation. The resulting Qualiveen (Qualiveen is a pending registration trade mark of Coloplast A/S, DK-3050 Humlebaek, Denmark) questionnaire underwent multi-trait and principal component analysis and the test-retest reliability of the questionnaire was examined in stable patients.

RESULTS

Patient interviews identified 257 concepts relevant to SCI patients with urinary disorders. Item reduction led to a 30-item questionnaire, which was psychometrically validated in 281 SCI patients with UD. The median age of patients was 41 years, 78% were male and the majority were paraplegic (55%). The construct and clinical validity of the Qualiveen was confirmed, as well as its reliability in patients whose condition was stable over a 15-day period. Patients confirmed that it was easy to understand, complete and comprehensive.

CONCLUSIONS

The Qualiveen is a reliable and psychometrically validated instrument that may be used to measure the QoL of SCI patients with UD.

The National Birth Defects Prevention Study

The National Birth Defects Prevention Study was designed to identify infants with major birth defects and evaluate genetic and environmental factors associated with the occurrence of birth defects. The ongoing case-control study covers an annual birth population of 482,000 and includes cases identified from birth defect surveillance registries in eight states. Infants used as controls are randomly selected from birth certificates or birth hospital records. Mothers of case and control infants are interviewed and parents are asked to collect buccal cells from themselves and their infants for DNA testing. Information gathered from the interviews and the DNA specimens will be used to study independent genetic and environmental factors and gene-environment interactions for a broad range of birth defects. As of December 2000, 7,470 cases and 3,821 controls had been ascertained in the eight states. Interviews had been completed with 70% of the eligible case and control mothers, buccal cell collection had begun in all of the study sites, and researchers were developing analysis plans for the compiled data. This study is the largest and broadest collaborative effort ever conducted among the nation's leading birth defect researchers. The unprecedented statistical power that will result from this study will enable scientists to study the epidemiology of some rare birth defects for the first time. The compiled interview data and banked DNA of approximately 35 categories of birth defects will facilitate future research as new hypotheses and improved technologies emerge.

Pharmacokinetics of enoxacin and its oxometabolite after multiple oral dosing and penetration into prostatic tissue

The objective of this study was to determine the concentrations of enoxacin and its oxo-metabolite in human prostatic tissue after multiple oral doses (400 mg bd) in 13 patients. On the first day of treatment, elimination half-lives were 6.8 h for enoxacin and 7.1 h for its metabolite; they were increased on day 4 (10.3 and 13.2 h, respectively). The ratios of drug concentration in prostatic tissue and plasma averaged 2.2 for enoxacin and 1.4 for its metabolite. In conclusion, concentrations of enoxacin achieved within the prostatic tissue were higher than plasma concentrations suggesting that there was an active transport mechanism.

Artificial urinary sphincter AMS 800 for urinary incontinence after radical prostatectomy: the French experience

Post-radical prostatectomy urinary incontinence (PRP-UI) has a major negative impact on the patient's quality of life with the incidence accounting for over 30% on a patient questionnaire basis. In 1995 the French Urological Association started a prospective survey to investigate the efficacy and safety of the AMS 800 artificial urinary sphincter (AUS) in PRP-UI, and preliminary results are presented for the 103 men enrolled in the study in whom bulbar urethral cuff placement was used exclusively. Surgical revision was necessary in 22 patients (21%). Infection and erosion accounted for 12 non-mechanical revisions leading to complete removal of 6 AUS and to eventual replacement of 6 devices with new ones. Mechanical malfunction accounted for revision in l0 patients (9.7%). Fifty-nine patients (61.45%) reported no leakage for the 96 working devices. Twenty-seven patients (28%) wore no pads, 3 patients used 1 pad and 4 patients used 2 pads/day, and all these patients reported improvement, with only 3 patients (3%) having had more than 2 pads/day. Currently, no non-prosthetic procedure reliably affords such good objective results. Insertion of the AMS 800 AUS no doubt represents an attractive treatment modality available for male urinary incontinence following radical prostatectomy.

[Simultaneous radio-chemotherapy for infiltrating bladder carcinoma. What is new since 1997?]

Concomitant radiotherapy-chemotherapy is increasingly used in urology in the treatment of invasive bladder tumours. In 1997, the outcome of 552 patients was reported in the international literature. Two years later, another 617 patients had been treated according to various modalities. The initial complete response rate ranged from 56 to 87% (median: 70%). 5-year overall survival rates were between 55 and 68% for T2 tumours. The metastasis rate was between 22 and 35% for the overall treated population. Concomitant radiotherapy-chemotherapy using a platinum salt represents a possible therapeutic modality in some patients, but it cannot be considered to be equivalent to total cystectomy, which remains the reference treatment in operable patients with an operable tumour, achieving a 63 to 80% 5-year survival for pT2 tumours.

Carotid surgery without angiography is possible and safe

BACKGROUND

To evaluate the possibility to perform carotid surgery without angiography.

METHODS

From January 1994 to June 1998, 514 patients with carotid obstructive disease were operated upon, 225 of them (43.8%) without previous angiography; 55 out of 68 (80.8%) during the last six months. Eighty-one (36.0%) had lateralizing symptoms, 50 aspecific ones (22.2%) and 94 were asymptomatic (41.8%). All patients were investigated by color-coded duplex sonography (CDS) of the arteries at the neck and by transcranial Doppler (TCD) and computed tomography (CT). One hundred eighty-eight patients were operated upon under local anaesthesia and 37 under general anesthesia; 204 had a carotid endartereotomy (90.7%) with patch angioplasty in 154 (75.5%), and 21 required a bypass graft (9.3%). In 26 patients (11.5%) an indwelling shunt was needed.

RESULTS

Findings at surgery were consistent with CDS for plaque composition, ulcerations and degree of stenosis. There were no early deaths. Neurologic or ocular deficits occurred in 2 cases (0.9%). No strokes were observed in follow-up from 6 to 34 months.

CONCLUSIONS

Carotid endarterectomy can be done without angiography in selected cases provided CDS plus TCD are of high quality. Under such conditions it can be considered a safer way to deal with carotid obstructive disease.

Compression wood-responsive proteins in developing xylem of maritime pine (Pinus pinaster ait.)

When a conifer shoot is displaced from its vertical position, compression wood (CW) is formed on the under side and can eventually return the shoot to its original position. Changes in cell wall structure and chemistry associated with CW are likely to result from differential gene/protein expression. Two-dimensional polyacrylamide gel electrophoresis of differentiating xylem proteins was combined with the physical characterization of wooden samples to identify and characterize CW-responsive proteins. Differentiating xylem was harvested from a 22-year-old crooked maritime pine (Pinus pinaster Ait.) tree. Protein extracted from different samples were revealed by high-resolution silver stained two-dimensional polyacrylamide gel electrophoresis and analyzed with a computer-assisted system for single spot quantification. Growth strain (GS) measurements allowed xylem samples to be classified quantitatively from normal wood to CW. Regression of lignin and cellulose content on GS showed that an increase in the percentage of lignin and a decrease of the percentage of cellulose corresponded to increasing GS values, i.e. CW. Of the 137 studied spots, 19% were significantly associated with GS effect. Up-regulated proteins included 1-aminocyclopropane-1-carboxylate oxidase (an ethylene forming enzyme), a putative transcription factor, two lignification genes (caffeic O-methyltransferase and caffeoyl CoA-O-methyltransferase), members of the S-adenosyl-L-methionine-synthase gene family, and enzymes involved in nitrogen and carbon assimilation (glutamine synthetase and fructokinase). A clustered correlation analysis was performed to study simultaneously protein expression along a gradient of gravistimulated stressed xylem tissue. Proteins were found to form "expression clusters" that could identify: (a) Gene product under similar control mechanisms, (b) partner proteins, or (c) functional groups corresponding to specialized pathways. The possibility of obtaining regulatory correlations and anticorrelations between proteins provide us with a new category of homology (regulatory homology) in tracing functional relationships.

Multiple HLA-class I-specific inhibitory NK receptor expression and IL-4/IL-5 production by CD8+ T-cell clones in HIV-1 infection

Several mechanisms may contribute to the decline in HIV-1 specific CD8+ cytotoxic T-lymphocyte (CTL) activity that is observed in infected patients, including loss of CD4+ cell help, antigenic shift, impaired clonogenicity and functional impairment due to expression of inhibitory NK receptors (iNKRs). In addition to a decrease in HIV-1-specific cytolytic activity, an increased proportion of CD8+ T-cells producing IL-4 and IL-5 has been recently observed in advanced HIV-1 infection. Remarkably, an impaired HIV-1-specific CTL activity was primarily detected among the TC0/Tc2 CD8+ CTLs. A series of CD3+CD8+ T-cell clones expressing inhibitory NK receptors (iNKRs) isolated from HIV-1 infected patients was analyzed in order to determine their cytokine production pattern and to assess the extent of iNKR expression at the single cell level. Our data indicate that iNKR+CD3+CD8+ clones isolated from infected patients frequently express multiple iNKR and may produce IL-4 and IL-5 to a relevant extent.

Rupture of Dacron aorto-femoral graft. Case report

A 74-year-old patient was admitted to our department in a serious general condition due to massive bleeding. He had been treated 10 years previously in another hospital with an aorto-bifemoral bypass for obstructive disease using a knitted-Dacron graft. A large pulsating mass was present in the right iliac fossa as well as enormous pulsating enlargement of the scrotum. Echo color-Doppler investigation detected dilation up to 5 cm in diameter of the right branch of the graft and a large perigraft hematoma communicating with a similar mass in the scrotum. The patient was submitted to emergency surgery and a large rupture of the graft was found. The dilated segment was resected and replaced by a new 8 mm Dacron graft. Postoperative course was uneventful.

[Loco-regional block in ophthalmic surgery: single drug or drug combination with hyaluronidase? Randomized prospective study]

The aim of this study is the comparison between the use of bupivacaine alone and a mixture of bupivacaine, mepivacaine and hyaluronidase in both retrobulbar and peribulbar blockades for eye surgery. Three hundred ninety-nine consecutive adult patients scheduled for cataract surgery with regional anaesthesia were included in this prospective, randomized and partially blind study. Peribulbar blockade was performed on 199 patients (group P). Ninety-nine of them received a mixture of local anaesthetics and hyaluronidase (sub-group M), while 100 received bupivacaine alone (sub-group B). Retrobulbar blockade was performed on 200 patients (group R): 100 of them received the mixture with hyaluronidase (sub-group M), while 100 received bupivacaine (sub-group B). The interval between anaesthesia and motor blockade (onset time), the presence of residual ocular movements, the need of further anaesthesia, the quality of anaesthesia, the ocular tone, the length of anaesthesia and possible complications were registered.

RESULTS

Retrobulbar blockade has the only advantage of a shorter onset time, while peribulbar blockade shows a longer anaesthetic effect. Mixture with hyaluronidase (the sub-group M) has a shorter onset time, a lesser need of further anaesthesia, fewer residual ocular movements and a better quality of anaesthesia.

CONCLUSIONS

Local anaesthetics mixture with hyaluronidase associated with peribulbar blockade presents the advantages of rapidity, duration and better quality without the risks of retrobulbar blockade side effects.

Systolic blood pressure within an intermediate range may reduce memory loss in an elderly hypertensive cohort

The objective of this study was to determine if maintenance of systolic blood pressure (BP) within a high range or low range among treated hypertensive patients increases the risk of memory decline. Biennial neuropsychological evaluations were performed on 158 hypertensive subjects. Decline/year was measured on the Cued Selective Reminding test (total free recall and delayed recall) in three systolic BP groups (low-i.e., mean systolic BP during the follow-up period < 135 mm Hg; intermediate-i.e., 135 mm Hg < or = mean systolic BP < or = 150 mm Hg; high-i.e., mean systolic BP > 150 mm Hg). In total free recall, the three systolic BP groups had significantly different declines per year (P = .02), with patients in the high subgroup showing the greatest decline. In delayed recall, the three systolic BP groups also showed significantly different declines per year (P = .04), with patients in the low subgroup having the greatest decline. Chronically elevated systolic BP > 150 mm Hg is associated with accelerated memory decline compared to older treated hypertensive patients with systolic BP in an intermediate range. Chronically maintained systolic BP within a low normal range < 135 mm Hg in older treated hypertensive subjects may be associated with accelerated memory decline, specifically in a test of delayed memory recall, compared to patients with systolic BP in an intermediate range. Optimal regulation of systolic BP may be a potential modifiable risk factor to prevent or minimize memory loss in older hypertensive patients.

Efficient and regulated erythropoietin production by naked DNA injection and muscle electroporation

We show that an electric treatment in the form of high-frequency, low-voltage electric pulses can increase more than 100-fold the production and secretion of a recombinant protein from mouse skeletal muscle. Therapeutical erythopoietin (EPO) levels were achieved in mice with a single injection of as little as 1 microgram of plasmid DNA, and the increase in hematocrit after EPO production was stable and long-lasting. Pharmacological regulation through a tetracycline-inducible promoter allowed regulation of serum EPO and hematocrit levels. Tissue damage after stimulation was transient. The method described thus provides a potentially safe and low-cost treatment for serum protein deficiencies.

Separation and characterization of needle and xylem maritime pine proteins

Two-dimensional gel electrophoresis (2-DE) and image analysis are currently used for proteome analysis in maritime pine (Pinus pinaster Ait.). This study presents a database of expressed proteins extracted from needles and xylem, two important tissues for growth and wood formation. Electrophoresis was carried out by isoelectric focusing (IEF) in the first dimension and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the second. Silver staining made it possible to detect an average of 900 and 600 spots on 2-DE gels from needles and xylem, respectively. A total of 28 xylem and 35 needle proteins were characterized by internal peptide microsequencing. Out of these 63 proteins, 57 (90%) could be identified based on amino acid similarity with known proteins, of which 24 (42%) have already been described in conifers. Overall comparison of both tissues indicated that 29% and 36% of the spots were specific to xylem and needles, respectively, while the other spots were of identical molecular weight and isoelectric point. The homology of spot location in 2-DE patterns was further validated by sequence analysis of proteins present in both tissues. A proteomic database of maritime pine is accessible on the internet (http://www.pierroton.inra.fr/genetics/2D/).

IL-12-mediated NKRP1A up-regulation and consequent enhancement of endothelial transmigration of V delta 2+ TCR gamma delta+ T lymphocytes from healthy donors and multiple sclerosis patients

Gamma delta T lymphocytes are thought to play a role in the pathogenesis of multiple sclerosis (MS) contributing to demyelinization and fibrosis in the central nervous system. In this study, we show that, in MS patients with active disease, the percentage of circulating V delta 2+ gamma delta T cells coexpressing NKRP1A is significantly increased compared with healthy donors. V delta 2+ and V delta 1+ T cells were sorted from MS patients and healthy volunteers and cloned. At variance with V delta 1+ clones, all V delta 2+ clones expressed NKRP1A, which was strongly up-regulated upon culture with IL-12; this effect was neutralized by specific anti-IL-12 Abs. No up-regulation of NKRP1A by IL-12 was noted on V delta 1+ clones. RNase protection assay showed that IL-12R beta 2 subunit transcript was significantly less represented in V delta 1+ than V delta 2+ clones. This finding may explain the different effect exerted by IL-12 on these clones. In transendothelial migration assays, V delta 2+ NKRP1A+ clones migrated more effectively than V delta 1+ clones, and this migratory potential was enhanced following culture with IL-12. Migration was strongly inhibited by the F(ab')2 of an anti-NKRP1A Ab, suggesting that this lectin is involved in the migration process. We also show that, in freshly isolated PBMC from MS patients, the migrated population was enriched for V delta 2+ NKRP1A+ cells. We conclude that the expression of NKRP1A on V delta 2+ cells is associated with increased ability to migrate across the vascular endothelium and that this phenomenon may be regulated by IL-12 present in the microenvironment.

[Re-evaluation of the diagnosis in congenital hypothyroidism]

Newborn screening for congenital hypothyroidism (CH) has become routine in Italy. It provided new information regarding the epidemiology, diagnosis and treatment of CH infants and allowed to identify transient disorders of thyroid function in infancy. In fact, when the permanence of hypothyroidism has not been established in the newborn period, a confirmation of the diagnosis at 2-3 years of life should be performed. In this study results regarding the diagnosis reevaluation performed in 23 out of 184 CH children followed at the follow-up center for CH of the University of Rome "La Sapienza", are reported. Eleven of 23 reevaluated children had transient hypothyroidism (TH) and permanent CH was confirmed in the others. Four of the 11 TH children had law gestational age at birth, 1 had high antithyroid peroxidase titre due to maternal autoimmune thyroiditis and 2 were resident in iodine deficient areas. Our results show the importance of diagnosis reevaluation to identify transient disorders of thyroid function in infancy and confirm the role of neonatal, maternal and environmental factors in the etiopathogenesis of TH.

Randomized comparison of transurethral electroresection and holmium: YAG laser vaporization for symptomatic benign prostatic hyperplasia

OBJECTIVE

To evaluate the safety and efficacy of holmium:YAG laser vaporization v transurethral electroresection (TURP) for benign prostatic hyperplasia.

PATIENTS AND METHODS

Thirty-six patients were randomized. Two laser procedures (60 to 80 W) were performed for one TURP. Symptom Score, peak flow rate, potency, and ejaculation status were measured at baseline and at 1, 3, 6, and 12 months.

RESULTS

The mean operative time was 75 minutes for laser and 56 minutes for TURP (P = 0.0407). With a mean laser energy delivered of 103.6 kJ, hemostasis was satisfactory during vaporization. The mean catheterization time was 1.7 and 2.1 days in the laser and TURP group, respectively. For the laser and TURP groups, the mean AUA Score improved from 20 preoperatively to 7 and from 24.1 to 5, respectively, at 12 months. The mean peak flow increased from 8.4 to 19.5 mL/sec and from 7.6 to 16.8 ml/sec, respectively, at 12 months. These results are not statistically different. No significant initial dysuria occurred. No significant difference between the groups appeared in potency or ejaculatory status during the follow-up. One patient in the laser group (Day 5) and two in the TURP group (2nd and 6th month) had to undergo a second procedure to relieve obstruction.

CONCLUSION

Although taking slightly longer to accomplish, holmium:YAG laser vaporization of BPH provides early results very similar to those of TURP with a shorter catheterization time and no initial dysuria or pain.

The relationship of anxiety and depression with self-reported knee pain in the community: data from the Baltimore Longitudinal Study of Aging

OBJECTIVE

To investigate the relationship between anxiety and depression and reporting of knee pain in the community.

METHODS

Subjects (n = 374) were community volunteers aged 40 years and above who are participants in the Baltimore Longitudinal Study of Aging, a prospective multidisciplinary research study of normative aging. Knee pain was defined by the First National Health and Nutrition Examination Survey question "have you ever had pain in or around your knee on most days for at least one month?"; anxiety and depression were measured by the relevant subscales of the Arthritis Impact Measurement Scales questionnaire. All subjects had standing anteroposterior radiographs, read for Kellgren and Lawrence (K + L) grade.

RESULTS

After adjustment for age, women reporting "ever" knee pain had significantly higher anxiety scores than those reporting "never" pain (3.06 +/- 0.26 versus 2.35 +/- 0.17; P = 0.025). Pain reporting was related neither to anxiety scores in men, nor to depression in either sex. Analysis stratified by radiographic severity, adjusted for age and gender, showed that differences in anxiety were confined to those reporting knee pain in the absence of radiographic change (i.e., K + L grade 0).

CONCLUSIONS

In the community, women reporting knee pain in the absence of radiographic osteoarthritis have higher anxiety scores than those without pain. Depression was not significantly related to knee pain in this population. Psychosocial factors may explain some of the discrepancy between reported knee pain and structural change as seen on x-ray.