Assessing oral health and the minimally important differences in oral health-related quality of life of non-diabetic and diabetic patients: a cross-sectional study

BACKGROUND

Non-diabetics and diabetics might have different oral health problems and impacts on their oral health-related quality of life (OHRQoL). Comparison of oral health status and coping strategies between these patients, and evaluation of factors associated with OHRQoL might facilitate better treatment planning for improved patient-centred outcome.

METHODS

One hundred and eleven non-diabetics and 107 diabetics attending a public hospital were clinically examined and evaluated for coping strategies (abbreviated coping orientation to problems experienced) and OHRQoL [short-form oral health impact profile (OHIP-14S)]. Factors associated with OHRQoL were analysed through correlation/partial correlation. Minimally important differences (MID) of OHIP-14S were calculated to confirm associations between attachment loss, caries, and tooth loss with OHRQoL.

RESULTS

Non-diabetics had worse periodontal status. Diabetics had more missing teeth. Non-diabetics and diabetics employed maladaptive coping to manage oral health problems. Overall, non-diabetics reported worse OHRQoL. Determination of MID showed that non-diabetics with high-severe attachment loss and <20 teeth experienced poorer OHRQoL. Diabetics with caries, high-severe attachment loss, and <25 teeth experienced poorer OHRQoL.

CONCLUSION

Different factors were associated with OHRQoL of non-diabetics and diabetics. Delivery of treatment aimed at maintaining teeth in a periodontally healthy and caries free state, and provision of more chewing units might help improve OHRQoL of diabetics. © 2024 Australian Dental Association.

Experience Learned and Perspectives on Using Model-Integrated Evidence in the Regulatory Context for Generic Drug Products-a Meeting Report

This report summarizes relevant insights and discussions from a 2022 FDA public workshop titled Best Practices for Utilizing Modeling Approaches to Support Generic Product Development which illustrated how model-integrated evidence has been used and can be leveraged further to inform generic drug product development and regulatory decisions during the assessment of generic drug applications submitted to the FDA. The workshop attendees discussed that model-integrated evidence (MIE) approaches for generics are being applied in the space of long-acting injectable (LAI) products to develop shorter and more cost-effective alternative study designs for LAI products. Modeling and simulation approaches are utilized to support virtual BE assessments at the site of action for locally acting drug products and to assess the impact of food on BE assessments for oral dosage forms. The factors contributing to the success of the model-informed drug development program under PDUFA VI were discussed. The generic drug industry shared that decisions on formulation candidate/formulation variant selection, on pilot in vivo bioavailability studies, and on alternative study designs for BE assessment are informed by modeling and simulation approaches. There was agreement that interactions between the regulatory agencies and the industry are desirable because they improve the industry's understanding of scientific and other regulatory considerations on implementing modeling and simulation approaches in drug development and regulatory submissions.

Drug Permeability - Best Practices for Biopharmaceutics Classification System (BCS)-Based Biowaivers: A workshop Summary Report

The workshop "Drug Permeability - Best Practices for Biopharmaceutics Classification System (BCS) Based Biowaivers" was held virtually on December 6, 2021, organized by the University of Maryland Center of Excellence in Regulatory Science and Innovation (M-CERSI), and the Food and Drug Administration (FDA). The workshop focused on the industrial, academic, and regulatory experiences in generating and evaluating permeability data, with the aim to further facilitate implementation of the BCS and efficient development of high-quality drug products globally. As the first international permeability workshop since the BCS based biowaivers was finalized as the ICH M9 guideline, the workshop included lectures, panel discussions, and breakout sessions. Lecture and panel discussion topics covered case studies at IND, NDA, and ANDA stages, typical deficiencies relating to permeability assessment supporting BCS biowaiver, types of evidence that are available to demonstrate high permeability, method suitability of a permeability assay, impact of excipients, importance of global acceptance of permeability methods, opportunities to expand the use of biowaivers (e.g. non-Caco-2 cell lines, totality-of-evidence approach to demonstrate high permeability) and future of permeability testing. Breakout sessions focused on 1) in vitro and in silico intestinal permeability methods; 2) potential excipient effects on permeability and; 3) use of label and literature data to designate permeability class.

Establishing the suitability of model-integrated evidence to demonstrate bioequivalence for long-acting injectable and implantable drug products: Summary of workshop

On November 30, 2021, the US Food and Drug administration (FDA) and the Center for Research on Complex Generics (CRCG) hosted a virtual public workshop titled "Establishing the Suitability of Model-Integrated Evidence (MIE) to Demonstrate Bioequivalence for Long-Acting Injectable and Implantable (LAI) Drug Products." This workshop brought relevant parties from the industry, academia, and the FDA in the field of modeling and simulation to explore, identify, and recommend best practices on utilizing MIE for bioequivalence (BE) assessment of LAI products. This report summerized presentations and panel discussions for topics including challenges and opportunities in development and assessment of generic LAI products, current status of utilizing MIE, recent research progress of utilizing MIE in generic LAI products, alternative designs for BE studies of LAI products, and model validation/verification strategies associated with different types of MIE approaches.

Regulatory utility of physiologically-based pharmacokinetic modeling to support alternative bioequivalence approaches and risk assessment: A workshop summary report

This report summarizes the proceedings for day 2 sessions 1 and 3 of the 2-day public workshop entitled "Regulatory Utility of Mechanistic Modeling to Support Alternative Bioequivalence Approaches," a jointly sponsored workshop by the US Food and Drug Administration (FDA) and the Center for Research on Complex Generics (CRCG). The aims of this workshop were: (1) to discuss how mechanistic modeling, including physiologically-based pharmacokinetic (PBPK) modeling and simulation, can support product development, and regulatory submissions; (2) to share the current state of mechanistic modeling for bioequivalence (BE) assessment through case studies; (3) to establish a consensus on best practices for using PBPK modeling for BE assessment to help drive further investment by the generic drug industry into mechanistic modeling and simulation; and (4) to introduce the concept of a Model Master File to improve model-sharing. The theme of day 2 covered PBPK absorption model for oral products as an alternative BE approach and a tool for supporting risk assessment and biowaiver (session 1), oral PBPK for evaluating the impact of food on BE (session 2), successful cases, and challenges for oral PBPK (session 3). This report summarizes the topics of the presentations of day 2 sessions 1 and session 3 from FDA, academia, and pharmaceutical industry, including the current status of oral PBPK, case examples as well as the challenges and opportunities in this area. In addition, panel discussions on the utility of oral PBPK in both new drugs and generic drugs from regulatory and industry perspective are also summarized.

The pharmacokinetic and safety profile of single-dose deferiprone in subjects with sickle cell disease

Patients with sickle cell disease (SCD) who undergo repeated blood transfusions often develop iron overload. Deferiprone (Ferriprox®) is an oral iron chelator indicated for the treatment of transfusional iron overload due to thalassemia syndromes and has been recently approved as a treatment for iron overload in adult and pediatric patients with SCD and other anemias. The present study aims to characterize the pharmacokinetic (PK) profile of deferiprone (DFP) in adult subjects with SCD. In this phase I, open-label study, subjects with SCD were administered a single 1500 mg dose of DFP. Blood and urine samples were collected for PK assessments of DFP and its main metabolite, deferiprone 3-O-glucuronide (DFP-G). Eight subjects were enrolled and completed the study. Following drug administration, serum levels of DFP and DFP-G rose to maximum concentrations at 1.0 and 2.8 h post-dose, respectively. The half-lives of DFP and DFP-G were 1.5 and 1.6 h, respectively. The majority of administered drug was metabolized and excreted as DFP-G, with less than 4% excreted unchanged in urine up to 10 h post-dose. Subjects received a safety assessment 7 (± 3) days post-dose. Two subjects reported mild adverse events unrelated to the study drug, and no other safety concerns were reported. The PK profile of DFP in SCD subjects is consistent with previous reports in healthy adult volunteers, suggesting no special dosing adjustments are indicated for this population. These findings provide valuable insight for treating iron overload in patients with SCD, who have limited chelation therapy treatment options (trial registration number: NCT01835496, date of registration: April 19, 2013).

Evaluation of the efficacy and safety of deferiprone compared with deferasirox in paediatric patients with transfusion-dependent haemoglobinopathies (DEEP-2): a multicentre, randomised, open-label, non-inferiority, phase 3 trial

BACKGROUND

Transfusion-dependent haemoglobinopathies require lifelong iron chelation therapy with one of the three iron chelators (deferiprone, deferasirox, or deferoxamine). Deferasirox and deferiprone are the only two oral chelators used in adult patients with transfusion-dependent haemoglobinopathies. To our knowledge, there are no randomised clinical trials comparing deferiprone, a less expensive iron chelator, with deferasirox in paediatric patients. We aimed to show the non-inferiority of deferiprone versus deferasirox.

METHODS

DEEP-2 was a phase 3, multicentre, randomised trial in paediatric patients (aged 1 month to 18 years) with transfusion-dependent haemoglobinopathies. The study was done in 21 research hospitals and universities in Italy, Egypt, Greece, Albania, Cyprus, Tunisia, and the UK. Participants were receiving at least 150 mL/kg per year of red blood cells for the past 2 years at the time of enrolment, and were receiving deferoxamine (<100 mg/kg per day) or deferasirox (<40 mg/kg per day; deferasirox is not registered for use in children aged <2 years so only deferoxamine was being used in these patients). Any previous chelation treatment was permitted with a 7-day washout period. Patients were randomly assigned 1:1 to receive orally administered daily deferiprone (75-100 mg/kg per day) or daily deferasirox (20-40 mg/kg per day) administered as dispersible tablets, both with dose adjustment for 12 months, stratified by age (<10 years and ≥10 years) and balanced by country. The primary efficacy endpoint was based on predefined success criteria for changes in serum ferritin concentration (all patients) and cardiac MRI T2-star (T2*; patients aged >10 years) to show non-inferiority of deferiprone versus deferasirox in the per-protocol population, defined as all randomly assigned patients who received the study drugs and had available data for both variables at baseline and after 1 year of treatment, without major protocol violations. Non-inferiority was based on the two-sided 95% CI of the difference in the proportion of patients with treatment success between the two groups and was shown if the lower limit of the two-sided 95% CI was greater than -12·5%. Safety was assessed in all patients who received at least one dose of study drug. This study is registered with EudraCT, 2012-000353-31, and ClinicalTrials.gov, NCT01825512.

FINDINGS

435 patients were enrolled between March 17, 2014, and June 16, 2016, 393 of whom were randomly assigned to a treatment group (194 to the deferiprone group; 199 to the deferasirox group). 352 (90%) of 390 patients had β-thalassaemia major, 27 (7%) had sickle cell disease, five (1%) had thalassodrepanocytosis, and six (2%) had other haemoglobinopathies. Median follow-up was 379 days (IQR 294-392) for deferiprone and 381 days (350-392) for deferasirox. Non-inferiority of deferiprone versus deferasirox was established (treatment success in 69 [55·2%] of 125 patients assigned deferiprone with primary composite efficacy endpoint data available at baseline and 1 year vs 80 [54·8%] of 146 assigned deferasirox, difference 0·4%; 95% CI -11·9 to 12·6). No significant difference between the groups was shown in the occurrence of serious and drug-related adverse events. Three (2%) cases of reversible agranulocytosis occurred in the 193 patients in the safety analysis in the deferiprone group and two (1%) cases of reversible renal and urinary disorders (one case of each) occurred in the 197 patients in the deferasirox group. Compliance was similar between treatment groups: 183 (95%) of 193 patients in the deferiprone group versus 192 (97%) of 197 patients in the deferisirox group.

INTERPRETATION

In paediatric patients with transfusion-dependent haemoglobinopathies, deferiprone was effective and safe in inducing control of iron overload during 12 months of treatment. Considering the need for availability of more chelation treatments in paediatric populations, deferiprone offers a valuable treatment option for this age group.

FUNDING

EU Seventh Framework Programme.

Randomized, Blinded, Placebo- and Positive-Controlled Crossover Study to Determine the Effect of Deferiprone on the QTc Interval in Healthy Subjects

This study evaluated whether deferiprone, an oral iron chelator, acts to prolong the QT interval. Fifty healthy volunteers received single doses of each of the following: therapeutic dose of deferiprone (33 mg/kg), supratherapeutic dose (50 mg/kg), placebo, or moxifloxacin, a positive control known to significantly prolong QT interval. Following each dose, subjects underwent cardiac monitoring, pharmacokinetics assessments, and safety assessments. Based on the QT interval obtained using the Fridericia correction for heart rate (QTcF), the upper bound of the 1-sided 95% confidence interval of the mean difference between deferiprone and placebo was <10 milliseconds (the threshold of concern defined by authorities) at all time points for both doses: maximum difference of 3.01 milliseconds for the therapeutic dose and 5.23 milliseconds for the supratherapeutic dose. The difference in dQTcF between moxifloxacin and placebo demonstrated that the study was adequately sensitive to detect a significant prolongation of QTcF. The concentration-response correlation analyses revealed some weak but statistically significant trends of increase in dQTcF and ddQTcF with increasing exposure to deferiprone, but these trends should have no clinical consequence even at the recommended maximum dosage. In conclusion, there was no clinically meaningful effect on QTc interval following single therapeutic or supratherapeutic doses of deferiprone.

Effects of renal impairment on the pharmacokinetics of orally administered deferiprone

Aims

In light of the growing recognition of renal disease in thalassemia, it is important to understand the impact of renal impairment on the pharmacokinetics of iron chelators. This study evaluated the pharmacokinetics and safety of the iron chelator deferiprone (DFP) in subjects with renal impairment in comparison with healthy volunteers (HVs).

Methods

Thirty‐two subjects were categorized into four groups based on degree of renal impairment: none, mild, moderate or severe, as determined by estimated glomerular filtration rate (eGFR). All subjects received a single oral dose of 33 mg kg⁻¹ DFP, provided serum and urine samples for pharmacokinetic assessment over 24 h and were monitored for safety.

Results

Renal clearance of DFP decreased as renal impairment increased. However, based on C_max, AUC(0,t) and AUC(0,∞), there were no significant group differences in systemic exposure, because less than 4% of the drug was excreted unchanged in the urine. DFP is extensively metabolized to a renally excreted, pharmacologically inactive metabolite, deferiprone 3‐O‐glucuronide (DFP‐G), which exhibited higher C_max, AUC(0,t), AUC(0,∞) and longer t_max and t_1/2 in the renally impaired groups compared with HVs. The C_max and AUCs of DFP‐G increased as eGFR decreased. Overall, 75%–95% of the dose was retrieved in urine, either as DFP or DFP‐G, regardless of severity of renal impairment. With respect to safety, DFP was well tolerated.

Conclusions

These data suggest that no adjustment of the DFP dosage regimen in patients with renal impairment is necessary, as there were no significant changes in the systemic exposure to the drug.

BCS Biowaivers: Similarities and Differences Among EMA, FDA, and WHO Requirements

The Biopharmaceutics Classification System (BCS), based on aqueous solubility and intestinal permeability, has enjoyed wide use since 1995 as a mechanism for waiving in vivo bioavailability and bioequivalence studies. In 2000, the US-FDA was the first regulatory agency to publish guidance for industry describing how to meet criteria for requesting a waiver of in vivo bioavailability and bioequivalence studies for highly soluble, highly permeable (BCS Class I) drugs. Subsequently, the World Health Organization (WHO) and European Medicines Agency (EMA) published guidelines recommending how to obtain BCS biowaivers for BCS Class III drugs (high solubility, low permeability), in addition to Class I drugs. In 2015, the US-FDA became better harmonized with the EMA and WHO following publication of two guidances for industry outlining criteria for obtaining BCS biowaivers for both Class I and Class III drugs. A detailed review and comparison of the BCS Class I and Class III criteria currently recommended by the US-FDA, EMA, and WHO revealed good convergence of the three agencies with respect to BCS biowaiver criteria. The comparison also suggested that, by applying the most conservative of the three jurisdictional approaches, it should be possible for a sponsor to design the same set of BCS biowaiver studies in preparing a submission for worldwide filing to satisfy US, European, and emerging market regulators. It is hoped that the availability of BCS Class I and Class III biowaivers in multiple jurisdictions will encourage more sponsors to request waivers of in vivo bioavailability/bioequivalence testing using the BCS approach.

Patient acceptability, efficacy, and skin biophysiology of a cream and cleanser containing lipid complex with shea butter extract versus a ceramide product for eczema

OBJECTIVES

To investigate patient acceptability, efficacy, and skin biophysiological effects of a cream/cleanser combination for childhood atopic dermatitis.

SETTING

Paediatric dermatology clinic at a university teaching hospital in Hong Kong.

PATIENTS

Consecutive paediatric patients with atopic dermatitis who were interested in trying a new moisturiser were recruited between 1 April 2013 and 31 March 2014. Swabs and cultures from the right antecubital fossa and the worst eczematous area, disease severity (SCORing Atopic Dermatitis index), skin hydration, and transepidermal water loss were obtained prior to and following 4-week usage of a cream/cleanser containing lipid complex with shea butter extract (Ezerra cream; Hoe Pharma, Petaling Jaya, Malaysia). Global or general acceptability of treatment was documented as 'very good', 'good', 'fair', or 'poor'.

RESULTS

A total of 34 patients with atopic dermatitis were recruited; 74% reported 'very good' or 'good', whereas 26% reported 'fair' or 'poor' general acceptability of treatment of the Ezerra cream; and 76% reported 'very good' or 'good', whereas 24% reported 'fair' or 'poor' general acceptability of treatment of the Ezerra cleanser. There were no intergroup differences in pre-usage clinical parameters of age, objective SCORing Atopic Dermatitis index, pruritus, sleep loss, skin hydration, transepidermal water loss, topical corticosteroid usage, oral antihistamine usage, or general acceptability of treatment of the prior emollient. Following use of the Ezerra cream, mean pruritus score decreased from 6.7 to 6.0 (P=0.036) and mean Children's Dermatology Life Quality Index improved from 10.0 to 8.0 (P=0.021) in the 'very good'/'good' group. There were no statistically significant differences in the acceptability of wash (P=0.526) and emollients (P=0.537) with pre-trial products. When compared with the data of another ceramide-precursor moisturiser in a previous study, there was no statistical difference in efficacy and acceptability between the two products.

CONCLUSIONS

The trial cream was acceptable in three quarters of patients with atopic dermatitis. Patients who accepted the cream had less pruritus and improved quality of life than the non-accepting patients following its usage. The cream containing shea butter extract did not differ in acceptability or efficacy from a ceramide-precursor product. Patient acceptability is an important factor for treatment efficacy. There is a general lack of published clinical trials to document the efficacy and skin biophysiological effects of many of the proprietary moisturisers.

Dairy and nondairy beverage consumption for childhood atopic eczema: what health advice to give?

BACKGROUND

Many parents of children with atopic eczema (AE) practise empirical dietary avoidance and supplementation, and seek healthcare advice on whether consumption of dairy and nondairy beverages may be beneficial or detrimental for this condition.

AIM

We investigated if frequency of consumption of beverages was associated with disease severity and quality of life (QoL).

METHODS

Parent-reported frequency of drinks and beverages were recorded in consecutive children with AE, and disease severity (Nottingham Eczema Severity Score; NESS), QoL (Children's Dermatology Life Quality Index; CDLQI), skin hydration (SH), transepidermal water loss (TEWL), blood pressure (BP), resting heart rate (RHR) and body mass index (BMI) were evaluated.

RESULTS

AE was associated with worse QoL than miscellaneous non-AE skin diseases (P < 0.001). Compared with children without AE, there was a trend for children with AE to drink less milk (P = 0.06) and more miscellaneous beverages (such as Chinese herbal tea and soymilk; P = 0.03). In children with AE, NESS correlated with CDLQI (ρ = 0.66, P < 0.001) and reduced SH (ρ = -0.32, P < 0.001), whereas CDLQI correlated with a higher RHR (ρ = 0.25, P < 0.01). Multiple logistic regression showed that male sex (OR = 0.44, 95% CI 0.20-0.97; P = 0.04) and drinking fresh milk (OR = 0.42, 95% CI 0.20-0.93; P = 0.03) were independent factors associated with less severe disease. Moderate to severe impairment of CDLQI was associated with NESS (OR = 1.48, 95% CI 1.28-1.71; P < 0.001) and RHR (OR = 1.05, 95% CI 1.02-1.08; P < 0.01) but not with reported habits of beverage consumption. Concerning cardiovascular health in AE, frequency of formula milk consumption was associated with RHR (ρ = 0.17, P = 0.04), and soft drink consumption was associated with higher systolic blood pressure (SBP) (ρ = 0.18, P = 0.04).

CONCLUSION

This study provides evidence for parental/patient guidance. Children with AE who reported more fresh milk consumption had less severe disease. There was no correlation between consumption of nondairy beverages with disease severity or QoL, but frequency of soft drink consumption correlated with SBP. With these results being supported by a literature review, it is reasonable to advise parents that fresh milk can be consumed by unsensitized children with AE. Soft drinks and other beverages should not be consumed in excess for optimal cardiovascular health and for other health reasons.

Harmonization of regulatory approaches for evaluating therapeutic equivalence and interchangeability of multisource drug products: workshop summary report

Regulatory approaches for evaluating therapeutic equivalence of multisource (or generic) drug products vary among different countries and/or regions. Harmonization of these approaches may decrease the number of in vivo bioequivalence studies and avoid unnecessary drug exposure to humans. Global harmonization for regulatory requirements may be promoted by a better understanding of factors underlying product performance and expectations from different regulatory authorities. This workshop provided an opportunity for pharmaceutical scientists from academia, industry and regulatory agencies to have open discussions on current regulatory issues and industry practices, facilitating harmonization of regulatory approaches for establishing therapeutic equivalence and interchangeability of multisource drug products.

Harmonization of regulatory approaches for evaluating therapeutic equivalence and interchangeability of multisource drug products: workshop summary report

Regulatory approaches for evaluating therapeutic equivalence of multisource (or generic) drug products vary among different countries and/or regions. Harmonization of these approaches may decrease the number of in vivo bioequivalence studies and avoid unnecessary drug exposure to humans. Global harmonization for regulatory requirements may be promoted by a better understanding of factors underlying product performance and expectations from different regulatory authorities. This workshop provided an opportunity for pharmaceutical scientists from academia, industry and regulatory agencies to have open discussions on current regulatory issues and industry practices, facilitating harmonization of regulatory approaches for establishing therapeutic equivalence and interchangeability of multisource drug products.

Dissolution and in vivo evidence of differences in reference products: impact on development of generic drugs

The WHO List of International Comparator Pharmaceutical Products (CPP) For Equivalence Assessment of Interchangeable Multi-Source (Generic) Products will address an important issue in developing new generic drugs because it will identify the 'correct' reference product. This list will reduce unnecessary clinical studies in jurisdictions requiring new generics to be compared with brand products sold locally. Eventually, by employing the CPP, there will be a world-wide standard for brand and generic drugs, assuring the same level of quality internationally. The strategy of a single global reference is meritorious, but there are several hurdles to overcome. Most important is that the same brand may differ in dissolution and/or bioavailability in various jurisdictions, including some drugs with a narrow therapeutic index like phenytoin. Several examples are provided in this manuscript. This issue of regional differences has relevance, not only to the WHO list, but also to the matter of how safety and efficacy was established for that product in the first place. Normally, phase III clinical studies are conducted on a product manufactured in a single site, set to one standard. If the product differs in bioavailability in different jurisdictions, one is left with the question: 'which product has remained true to the original formulation?' Alternatively, if safety and efficacy is maintained with all formulations, then one is faced with the question: 'are the criteria currently employed for bioequivalence unnecessarily restrictive?'

High variability in drug pharmacokinetics complicates determination of bioequivalence: experience with verapamil

PURPOSE

For the assessment of bioequivalence it is assumed that drug clearance in each subject on each of the study days is the same and any observed differences in AUC and/or Cmax between a brand and generic formulation are due to differences in bioavailability. We hypothesized that this assumption was invalid for highly variable drugs such as verapamil and tested it by comparing bioavailability for the brand vs itself.

METHODS

To avoid any contribution from potential formulation differences, we evaluated bioavailability for isoptin SR 240 mg tablets in 9 healthy volunteers on 2 occasions separated by 1 week as part of a larger study. A validated HPLC assay was used to measure serial blood samples over 36 hours.

RESULTS

The AUC0-1 varied 3.8 fold among subjects and 5/9 subjects had > 30% difference in AUC0-1 on the 2 days. After log transformation, the mean AUC0-1 +/- %cv (ng.h/mL) on Occasion 1 (878 +/- 38) was 23% greater (p = 0.031) than on Occasion 2 (713 +/- 41). The 90% confidence interval of Occasion 1/Occasion 2 was 106-143%. The Cmax varied > 9 fold (30-278 ng/mL) among subjects. The intrasubject difference between days ranged from -46% to +298%. The 90% confidence interval was 72-152% for Cmax. Since the same lot of Isoptin was used in the same subjects on 2 occasions, the observed differences must be due to biological variability in verapamil pharmacokinetics, not formulation differences.

CONCLUSIONS

The intra-subject biological variability complicates bio-equivalence assessment and can lead to an erroneous assumption of bioinequivalence.

Double-cycle high-dose chemotherapy with peripheral blood stem cells and hematopoietic growth factor support in patients with advanced solid tumor. A pilot study by the Hong Kong Biotherapy Group

BACKGROUND

High-dose chemotherapy with autologous bone marrow transplantation has been useful in some patients with advanced breast, lymphoma, or germ cell tumors. Double-cycle high-dose chemotherapy may be able to deliver an even higher total dose within a given time period. It is important to determine whether peripheral blood stem cells and hematopoietic growth factors can diminish the hematopoietic toxicity of such a treatment.

METHODS

From November 1989 to May 1991, 14 patients were enrolled in two cycles of high-dose chemotherapy consisting of cyclophosphamide, 4.5 g/m2; cisplatin, 150 mg/m2; and etoposide, 900 mg/m2 in each cycle. The first five patients received peripheral blood stem cells harvested from 8-10 leukaphereses during steady state. The next nine patients, besides receiving peripheral blood stem cells mobilized by growth factors, also received either granulocyte-macrophage colony-stimulating factor (GM-CSF) at 250 micrograms/m2/day by two subcutaneous (s.c.) injections given 12 hours apart from day 6 until neutrophil recovery or granulocyte colony-stimulating factor (G-CSF) at 200 micrograms/m2 as daily s.c. injections.

RESULTS

For the first five patients, there was a median of 14 days from the first day of absolute marrow suppression to neutrophil count exceeding 500/microliters and a median of 15 days for a platelet count exceeding 20,000/microliters. For the next nine patients, with the use of either G-CSF or GM-CSF, there was a median of 8 days for a neutrophil count exceeding 500/microliters and and a median of 11 days for a platelet count exceeding 20,000/microliters.

CONCLUSION

With the use of peripheral stem cells and growth factors, high-dose chemotherapy could be given safely every 30 days with acceptable toxicity. A high complete response rate was seen in patients with nasopharyngeal carcinoma and in patients with small cell and non-small cell lung cancer who either had not received previous chemotherapy or who had responded to previous chemotherapy.

Short-duration in vitro interleukin-2-activated mononuclear cells for advanced cancer. A Hong Kong biotherapy pilot study trial

BACKGROUND

In vitro studies have demonstrated that a brief exposure of peripherally collected mononuclear cells to high-dose human recombinant interleukin-2(rIL-2) will generate a population of pulsed lymphokine-activated killer (LAK) cells. These cells have similar cytotoxicity against natural killer cells and resistant and sensitive target cells as compared with the standard LAK cells incubated for 3-7 days with rIL-2. Therefore, the authors conducted a pilot study to investigate the activity of pulsed LAK cells in patients with advanced cancer.

METHODS

Nineteen patients were enrolled in a pilot study, and pulsed LAK cell treatment was administered two times per week for 4 weeks, followed by similar cycles if patients remained free of disease progression and unacceptable toxic effects.

RESULTS

Toxic effects consisted mainly of fever, chills, nausea, and dizziness but were self-limiting and mild. Most cycles were administered on an outpatient basis. There were six partial responses (31%), occurring in two of three patients with renal cell carcinoma, two of four with hepatocellular carcinoma, one of seven with non-small cell lung carcinoma, and one of one with ovarian carcinoma. Two minimal responses were seen in one case each of melanoma and carcinoma of colon. Nine other patients had disease stabilization for 16 weeks, and two additional patients had disease progression. Phenotyping of peripheral mononuclear cells showed increases in CD56 and CD25 populations with no in vivo rIL-2 being administered after treatment with pulsed LAK cells.

CONCLUSIONS

The relative ease in generating pulsed LAK cells and the associated mild toxic effects enable prolonged stimulation of the effector cells of the patients against sensitive tumor targets, with a response rate comparable to those of high-dose rIL-2 and LAK cell treatment. Therefore, it may be a theoretically ideal adjuvant for patients with renal cell carcinoma, melanoma, and hepatoma and other applicable patients after bone marrow transplantation. The initial high response rate in patients with late-stage renal cell carcinoma and hepatocellular carcinoma indicates the need for additional confirmation.

Competitive binding of sulfamethazine and its N-acetylated metabolite

The protein binding of sulfamethazine (SMZ) was studied in rabbit serum. Serum solutions comprising various concentrations (approximately 0.01-3 mM) of SMZ and its major metabolite, N4-acetylsulfamethazine (AcSMZ), were prepared. These 'control' samples were also mixed via a Latin square design to study the interactive binding of SMZ and AcSMZ to the proteins. Equilibrium dialysis was conducted for 8 h. Post-dialysis measurement of SMZ/AcSMZ radioactivity in the buffer and serum chambers provided the free and bound fractions based upon equilibrium total serum concentrations. There was no significant change of protein concentration before and after dialysis. The 'control' data revealed concentration-dependent binding for both drugs while the interaction study clearly indicated the presence of competitive binding. Scatchard plots suggested the presence of more than one binding site. As a result, three different competitive binding models were examined via computer analysis of the observations. The most appropriate binding model was identified to consist of specific binding (protein concentration, Pt; dissociation constant, Kd) and nonspecific binding (Nsp). The mean (SD) 'control' parameter estimates for PtSMZ, PtAcSMZ, KdSMZ, KdAcSMZ, NspSMZ, NspAcSMZ were: 0.562(0.041), 0.605(0.024), 0.078(0.006), 0.031(0.002) [mM], 0.205(0.054), and 0.229(0.043), respectively. In the interaction study these values were: 0.599(0.022), 0.479(0.019), 0.091(0.004), 0.023(0.001), 0.228(0.020), and 0.434(0.061), respectively. The findings indicate that both drugs bind to albumin but the affinity of AcSMZ is greater than SMZ. Theoretically, the metabolite can therefore alter the in vivo SMZ binding thereby in turn causing apparent nonlinear acetylation based upon the pharmacokinetics of total SMZ concentrations.