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Hierarchical rule-based monitoring and fuzzy logic control for neuromuscular block.

OBJECTIVE: The important task for anaesthetists is to provide an adequate degree of neuromuscular block during surgical operations, so that it should not be difficult to antagonize at the end of surgery. Therefore, this study examined the application of a simple technique (i.e., fuzzy logic) to an almost ideal muscle relaxant (i.e., rocuronium) at general anaesthesia in order to control the system more easily, efficiently, intelligently and safely during an operation. METHODS: The characteristics of neuromuscular blockade induced by rocuronium were studied in 10 ASA I or II adult patients anaesthetized with inhalational (i.e., isoflurane) anaesthesia. A Datex Relaxograph was used to monitor neuromuscular block. And, ulnar nerve was stimulated supramaximally with repeated train-of-four via surface electrodes at the wrist. Initially a notebook personal computer was linked to a Datex Relaxograph to monitor electromyogram (EMG) signals which had been pruned by a three-level hierarchical structure of filters in order to design a controller for administering muscle relaxants. Furthermore, a four-level hierarchical fuzzy logic controller using the fuzzy logic and rule of thumb concept has been incorporated into the system. The Student's test was used to compare the variance between the groups. p < 0.05 was considered significant. RESULTS: The system achieved stable control of muscle relaxation with a mean T1% error of -0.19 (SD 0.66) % accommodating a range in mean infusion rate (MIR) of 0.21-0.49 mg x kg(-1) x h(-1). When these results were compared with our previous ones using the same hierarchical structure applied to mivacurium, less variation in the T1% error (p < 0.05) but the same variation in infusion rate were observed. The controller activity of these two drugs showed no significant difference (p > 0.5). However, the consistent medium coefficient variance (CV) of the MIR of both rocuronium (i.e., 36.13 (SD 9.35) %) and mivacurium (i.e., 34.03 (SD 10.76) %) indicated a good controller activity. CONCLUSIONS: The results showed that a hierarchical rule-based monitoring and fuzzy logic control architecture can provide stable control of neuromuscular block despite the considerable individual variation in neuromuscular block required among patients. Also, there was less variation in T1% error compared with that of previous study on mivacurium. Meanwhile, the consistent medium CV of the MIR of both rocuronium and mivacurium indicated a good controller activity which is able to withstand noise, diathermy effect, artifacts and surgical disturbances.

Adolescent↗

Troxacitabine: BCH 4556, SPD 758, Troxatyl.

Troxacitabine [BCH 4556; SPD 758; Troxatyl] is a DNA synthesis inhibitor. This profile has been selected from R&D Insight, a pharmaceutical intelligence database produced by Adis International Ltd. It is a member of a novel class of nucleoside analogues discovered by BioChem Pharma and is the first example of a synthetic L-nucleoside analogue to have shown anticancer activity in animal models. On 11 May 2001, BioChem Pharma was acquired by, and integrated into, Shire Pharmaceuticals Group. In February 2002 Shire announced that it intended to pursue development of troxacitabine as a treatment for solid tumours. In addition, Shire indicated that it would pursue the drug's development for acute myeloid leukaemia. In March 1999, phase II trials were initiated to investigate the efficacy and tolerability of troxacitabine in a variety of solid tumours including pancreas, prostate, colorectal, renal and non-small cell lung cancers and melanoma. The trials were conducted throughout North America and were closed to patient accrual in 2000. Two phase I combination chemotherapy trials in solid tumours (one with cisplatin and another with paclitaxel) have been initiated. One of these trials is in patients with pancreatic cancer. A phase III trial in patients with pancreatic cancer is expected to begin during the second or third quarter of 2003. In addition, further clinical development was initiated in May 2000, in the form of a combination chemotherapy trial in patients with acute leukaemia. A phase II trial in patients with acute myeloid leukaemia (AML) and chronic myeloid leukaemia-blast phase (CML-BP) has reported that troxacitabine demonstrated significant activity in these cancers. However, Shire indicated that no further development for CML-BP will be conducted. The company indicated that it would focus future development in the haematological malignancy area on AML and has initiated an exploratory phase III trial of troxacitabine in previously untreated patients with poor prognosis AML. The study will compare troxacitabine in combination with either cytarabine or idarubicin, with a control drug regimen. The aim is to identify the most promising treatment regimens in a relatively small number of patients before commencing the larger pivotal trial. A pivotal phase III trial is expected to begin in the first half of 2003. In September 2002, Shire Pharmaceuticals forecast Troxatyl to reach peak sales of $US100-200 million, for the indications of pancreatic cancer and myeloid leukaemia.

Antineoplastic Agents↗

Small caliber vascular grafts. Part II: Polyurethanes revisited.

Polyurethanes are considered to be one of the most bio- and blood-compatible biomaterials known today. By intelligent utilization of principles governing the structure/property relationship of these polymers, one can generate systems which resemble, in principle, the physical-mechanical behavior of living tissue. Thus, it is not surprising that these materials played a major role in development of small caliber vascular grafts targeted for vascular access, peripheral and coronary artery bypass indications. Numerous technologies, often esoteric in nature, were and are utilized to generate porous, potentially multilayered conduits possessing some or many characteristics of natural blood vessels. Properties such as durability, elasticity, compliance, pulsatility, and propensity for healing became attainable via polyurethanes. Furthermore, additional surface and/or bulk modification via attachments of biologically active species such as anticoagulants, cell proliferation suppressants, anti-infective compounds or biorecognizable groups are possible due to reactive groups which are part of the polyurethane structure. These modifications are designed to control or mediate host acceptance and healing of the graft. Finally, a myriad of practical processing technologies are used to fabricate functional grafts. Among those, casting, electrostatic and wet spinning of fibers and monofilaments, extrusion, dip coating or spraying of mandrels with polymer/additive solutions are often coupled with chemical-potential-difference-driven coagulation and phase inversion leading to grafts feeling and often behaving like natural vessels. Historically, the first polyurethanes utilized were hydrolytically unstable polyester polyurethanes containing hydrolysis-prone polyester polyols as soft segments, followed by hydrolytically stable but oxidation sensitive polyether polyols based polyurethanes. Polyether-based polyurethanes and their clones containing silicone and other modifying polymeric intermediates represented significant progress. Many viable technologies were discovered and developed using polyether-based polyurethanes. Chronic in vivo instability observed on prolonged implantation became, however, a major roadblock. The path led finally to the use of hydrolytically and oxidatively stable polycarbonate polyols as the soft segment to generate biodurable materials with resistance to biodegradation adequate for vascular access or perhaps peripheral graft indications. This biodurability needs to be further increased in order to utilize the full potential of polyurethanes in development of patent small caliber graft. Modification of both the soft and hard segments needs to be considered in order to maximize biodurability of both basic building blocks of the polyurethane. This paper reviews the achievements, discusses trends, and offers the view of the future in this exciting area of material/device combination.

Anti-Infective Agents↗

Mood-stabilizing drugs: are their neuroprotective aspects clinically relevant?

The possibility that there may be subtypes of bipolar disorder and the slow progress in understanding the therapeutic mechanism for approved mood-stabilizing drugs make the challenges of intelligent drug design seem daunting. Nonetheless, the numerous shortcomings in current pharmaco-therapy underscore the need to develop novel therapies. There are significant problems with currently approved mood-stabilizing drugs: 1. Up to 40% of patients fail to respond to monotherapy with either lithium or valproic acid. 2. Common use of polypharmacotherapy increases the side effects associated with treatment. 3. Treatment must continue for weeks to months for therapeutic effects to be greater than placebo. 4. Up to 60% of patients will discontinue therapy, which is somewhat attributable to unwanted side effects. Thus, it is critical that new medications without these problems be developed for bipolar disorder. The hypothesis that mood-stabilizing drugs are neuroprotective is an important first step in new drug development. To determine if the clinical efficacy of mood-stabilizing drugs is dependent on the neuroprotective or neurogenic properties of these medications, greater strides need to be made in relating findings from cell culture and animal models to human imaging and pathology. Mounting evidence supports the neuroprotective and neurogenic properties of lithium and valproic acid ina variety of cell-culture models. It is important for clinical, biochemical, and in vitro differences between these medications to be examined, not ignored,because these differences may reveal critical distinctions between the neural mechanisms of these drugs. Continuation of the in vitro work will aid in the understanding of the mechanism by which these drugs are neuroprotective,but such studies do not advance the understanding of whether these effects are critical for the clinical efficacy of these medications. In attempting to understand the in vivo effects of these medications, a variety of evidence supports the neuroprotective and neurogenic aspects of lithium and valproic acid in healthy rodents and animal models of gross brain insult. More work needs to be done to assess whether these effects occur in animal models for bipolar disorder. The proof of principle for supporting the claim that the neuroprotective or neurogenic properties are important clinically will come from longitudinal clinical studies that compare brain morphology and function before and during treatment. If enough evidence supports the hypothesis that the neuroprotective and neurogenic properties of mood-stabilizing drugs are important for their clinical efficacy, new medications that are more efficacious and have fewer side effects will be designed based on this discovery.

Affect↗

Erlotinib: CP 358774, NSC 718781, OSI 774, R 1415.

Erlotinib [Tarceva, R 1415, CP 358774, OSI 774, NSC 718781] is a small molecular, once-a-day, orally active inhibitor of the epidermal growth factor receptor tyrosine kinase. This profile has been selected from R&D Insight, a pharmaceutical intelligence database produced by Adis International Ltd. It is one of a class of anticancer drugs that target the underlying molecular mechanism involving oncogenes and tumour suppressor genes, which play critical roles in the conversion of normal cells into a cancerous state. Erlotinib is undergoing clinical development as an oral tablet by an alliance between OSI Pharmaceuticals, Genentech and Roche. OSI Pharmaceuticals, Genentech and Roche have entered an agreement for the global development and commercialisation of erlotinib. Under the terms of the agreement, Genentech and OSI will share costs and profit-taking for commercialising the product in the US. The overall costs of the development programme will be shared equally between the three companies. OSI will keep certain co-promotion rights in the US and Genentech will be responsible for commercialising the drug in the US should the FDA approve it. Roche will take the responsibility for obtaining regulatory approval and commercialisation in territories outside the US and pay royalties to OSI on net sales of the product in these markets. Initially, the alliance partners intend to pursue development of erlotinib in all the major tumour markets, particularly for non-small cell lung cancer (NSCLC) in which the group will focus on front-line combination approaches. Pfizer and OSI Pharmaceuticals in the US were developing erlotinib as a treatment for solid tumours. However, in June 2000, Pfizer merged with Warner-Lambert. The resulting company retained the Pfizer name, but in order to meet Federal Trade Commission requirements for the merger Pfizer granted all developmental and marketing rights for erlotinib to OSI Pharmaceuticals. This divestiture of the erlotinib portfolio, in effect, gave OSI a royalty-free, cashless license to the drug. In November 2001, OSI announced a partnership deal with HopeLink Corporation, a healthcare information technology company with an Internet-based Clinical Trial Service. The partnership will enable OSI to heighten awareness of its clinical trials and shorten patient accrual times. It will initially involve the presentation of the OSI phase III pancreatic and refractory NSCLC trials via Hopelink's Syndicated Network. In addition to this the two companies have also agreed to develop additional products and service together that will increase the efficiency of the clinical trial process, increase awareness of clinical trials, and enhance patient accrual techniques. OSI has also entered into an agreement with Therradex, a contract research organisation (CRO) to monitor phase II trials for erlotinib in NSCLC, ovarian and head and neck cancer. In addition, OSI entered into an agreement in 2001 with the US NCI. The NCI is conducting trials in a variety of different cancers. A phase III front-line NSCLC trial (TRIBUTE) of erlotinib in combination with carboplatin and paclitaxel was initiated in July 2001. The multicentre study is being conducted by Genentech in 1000 patients in the US, and will determine whether the addition of erlotinib to carboplatin chemotherapy is able to improve the duration of patient survival. Enrolment for this trial was completed in July 2002. An independent Data Monitoring Committee (DMC) has since reviewed the data from the trial and concluded that there are no safety or efficacy concerns that would warrant stopping the trial. However, the DMC did recommend stopping erlotinib at the time of disease progression or at the start of second-line therapy. A front-line phase III study of erlotinib in NSCLC (TALENT) in combination with gemcitabine and cisplatin chemotherapy was initiated by Roche in Europe in November 2001. Enrolment into this study was completed in September 2002, with approximately 1200 patients. Roche has confirmed that the study woulde has confirmed that the study would be included in the alliance's potential regulatory submission for front-line therapy in chemotherapy-naive patients in the US. Data from the trial is expected in the second half of 2003. OSI has opened two additional phase Ib studies to examine the potential of erlotinib in combination with carboplatin and paclitaxel in one study and gemcitabine and cisplatin in the other. A phase I study of erlotinib is also being conducted in patients with lung cancer in Japan. OSI received fast-track status from the US FDA in September 2002 for erlotinib as a second- or third-line treatment for patients with incurable stage IIIB/IV NSCLC who have failed to respond to standard therapy for advanced metastatic disease. Fast-track status was also granted to erlotinib in May 2002 for the treatment of chemotherapy-naive stage III/IV NSCLC. There are important differences between phase III studies of erlotinib and AstraZeneca's direct competitor drug gefitinib, which recently returned disappointing results in a frontline NSCLC trial with combination chemotherapy. In assessing the survival benefit of erlotinib with chemotherapy, the dose employed of 150 mg/day is the maximum tolerated dose (MTD), whereas the gefitinib trials were conducted at relatively lower doses than the MTD determined in earlier phase I studies. OSI is also investigating the survival benefit of erlotinib in a phase III study in refractory NSCLC patients, a key registration study. Patient size of the NSCLC trial was increased from 330 to 700 as OSI shifted emphasis from its pancreatic cancer trials. Phase II development for this indication was initiated based on data from a phase I trial, which had completed patient enrolment by April 2003. OSI and the US NCI signed a collaborative research agreement in 2001. The NCI is developing erlotinib through its CTEP programme for multiple tumour types including epithelial malignancies, gastrointestinal and genitourinary tracts, gynaecological malignancies and brain tumours. OSI supplies erlotinib for the trial, but the NCI provides the funding and manages the trials. A series of approximately ten phase Ib trials are already underway or were set to start in the US in 2001 to determine safety, tolerance and pharmacokinetic parameters of erlotinib in combination with a number of commonly used chemotherapeutic agents. The Wall Street Journal reported on 25 February 2002, that analysts at Robert Stephens, New York, USA, have forecast Tarceva to reach annual sales of >$US1 billion. Other analysts, at Merrill Lynch & Co., have predicted that products belonging to the same class as Tarceva could reach combined worldwide sales of $US6 billion to $US10 billion annually. In an earlier report by the Financial Times on 10 May 2001, it was stated that approximately 12 new anticancer agents are expected to be approved by the FDA through to the end of 2002. These agents, of which Tarceva is one, were said to have the potential to generate total sales of $US2.6 billion. Goldman Sachs have forecast Tarceva to reach peak sales of $US250 million for the indication of head and neck cancer alone. Previously in January 2001, the Financial Times claimed that OSI Pharmaceuticals, one of the development partners for Tarceva, stood to gain $US187 million pending regulatory approval. Genentech and Roche were each said to be buying $US35 million worth of OSI's stock and paying upfront fees. Tarceva is facing competition by two similar compounds, developed by AstraZeneca and ImClone, respectively.

Administration, Oral↗