Current Clinical Pharmacology - Volume 2, Issue 3, 2007

A direct approach to manipulate cardiac energy metabolism consists in modifying substrate utilization by the heart. Pharmacological agents that directly inhibit fatty acid oxidation include inhibitors of 3-ketoacyl coenzyme A thiolase (3-KAT), the last enzyme involved in β-oxidation. The most extensively investigated agents of this group of drugs are trimetazidine and ranolazine. Clinical studies have shown that these agents can substantially increase the ischemic threshold in patients with effort angina. However, the results of current research is also supporting the concept that shifting the energy substrate preference away from fatty acid metabolism and toward glucose metabolism by 3-KAT inhibitors could be an effective adjunctive treatment in patients with heart failure, in terms of left ventricular function and glucose metabolism improvement. In fact, these agents have also been shown to improve overall glucose metabolism in diabetic patients with left ventricular dysfunction. In this paper, the recent literature on the beneficial effects of this new class of drugs on left ventricular dysfunction and glucose metabolism is reviewed and discussed.

Malignant astrocytomas are aggressive neoplasms with a dismal prognosis despite optimal treatment. Maximal resective surgery is traditionally complemented by radiation therapy. Chemotherapy is typically used on patients with tumor recurrence, when their functional status is congruent with further treatment. The classic agents used are nitrosoureas, but temozolomide is gradually taking a more prominent role recently. New agents, biological modifiers, are increasingly used in clinical trials in an effort to affect the intrinsic biologic aberrations harboured by tumor cells. These drugs comprise differentiation agents, anti-angiogenic agents, matrix-metalloproteinase inhibitors and signal transduction inhibitors, among others. The issue of chemotherapy delivery is also crucial. Classically, agents are administered either intravenously or orally. In an effort to circumvent the obstacle imposed by the blood-brain barrier, investigators are actively working on more invasive methods of delivery, namely intra-arterial infusion with or without blood-brain barrier disruption or direct intra-cerebral administration, with clysis or drug-impregnated wafers. This article reviews the standard cytotoxic agents that have been used to treat malignant astrocytomas, and the different combination regimen offering promise. In addition, recent advances with biological modifiers are also discussed, along with alternate methods to deliver the agents more efficiently across the blood-brain barrier.

Introduction: The rabbit syndrome (RS) is a rare movement disorder generally associated with prolonged use of antipsychotics and characterized by inwilling, rhythmic, fast and fine movements of oral and masticatory muscles along the vertical axis of the mouth. Prevalence: The prevalence of RS ranges between 1.5% and 4.4%; middle and elderly ages, the female gender, aswell as past brain injuries are considered risk factors for its development. Pathophysiology: Although a dysbalance of the cholinergic and dopaminergic neurotransmission in the basal ganglia seems to be involved in the pathophysiology of RS, its precise mechanisms need to be clarified as yet. Relationships with antipsychotics: Fifty cases of RS have been published up-to-now: 34 and 10 occurred during treatments with typical and atypical antipsychotics, respectively, while 6 seemed unrelated to these drugs. Differential diagnosis: The differential diagnosis between RS and tardive dyskinesias involving the mouth may be based mainly on the evidence that in these last conditions the movements of the mouth are less regular and slower and involve the tongue. Treatment strategy: The available data suggest that RS responds favourably to anticholinergic drugs and to the change of the antipsychotic.

Computer technology has been advanced tremendously and the interest has been increased for the potential use of ‘Artificial Intelligence (AI)’ in medicine and biological research. One of the most interesting and extensively studied branches of AI is the ‘Artificial Neural Networks (ANNs)’. Basically, ANNs are the mathematical algorithms, generated by computers. ANNs learn from standard data and capture the knowledge contained in the data. Trained ANNs approach the functionality of small biological neural cluster in a very fundamental manner. They are the digitized model of biological brain and can detect complex nonlinear relationships between dependent as well as independent variables in a data where human brain may fail to detect. Nowadays, ANNs are widely used for medical applications in various disciplines of medicine especially in cardiology. ANNs have been extensively applied in diagnosis, electronic signal analysis, medical image analysis and radiology. ANNs have been used by many authors for modeling in medicine and clinical research. Applications of ANNs are increasing in pharmacoepidemiology and medical data mining. In this paper, authors have summarized various applications of ANNs in medical science.

Pain is a frequent and disabling symptom among multiple sclerosis (MS) and it is estimated to occur in 55% to 65% of patients. The mechanism of pain in MS has not yet been defined, because it can result from somatic, visceral, emotional, or neurologic impairment. The importance of this classification is related to different medical approaches to treat the pain in MS patients. In the management of symptomatic pain, new therapeutic strategies are now available to represent a great opportunity improving the quality of life. The availability of newer drugs for symptomatic treatment of pain in MS indicates a need to pay attention to this problem.

Levodopa , a prodrug of dopamine, remains to be one of the main drugs in the treatment of Parkinson's disease. All current levodopa products are formulated with aromatic amino acid decarboxylase inhibitors such as carbidopa or benserazide to prevent the metabolism of levodopa in the gastrointestinal tract and systemic circulation. Levodopa pharmacokinetic profiles remain unchanged after multiple doses, and are similar between healthy volunteers and patients and among patients at different stages of disease. Entacapone inhibits the metabolism of levodopa therefore increases the area under the plasma concentration-time profile of levodopa; however, it may decrease the initial absorption rate of levodopa in some patients probably due to competitive absorption. Food appears to affect the absorption of levodopa, but its effects vary with formulations. The results of positron emission tomography study suggest that a high protein diet may compete with the uptake of levodopa into the brain, therefore, may result in reduced levodopa effects. Since infusion studies demonstrated that it is beneficial to maintain stable plasma concentrations of levodopa, controlled-release formulations have been designed to provide prolonged absorption of levodopa. However, subsequent pharmacokinetic and pharmacodynamic studies demonstrated that a threshold concentration of levodopa appears to be necessary to switch patients “on”. Once patients are turned “on”, the duration of levodopa effects may be correlated with plasma concentration of levodopa. As such, more recent studies have demonstrated significant clinical benefits such as shorter time to “on” and longer duration of “on” when combining the immediate- and controlled-release levodopa products as compared to controlled-release levodopa products. Given these findings, it is important for physicians to understand the relationship between the pharmacokinetics and pharmacodynamics of levodopa in order to provide dosage regimens that meet patient needs. The pharmacokinetics and pharmacodynamics data of levodopa reported in the literature are reviewed here..

Cyclosporine A (CsA) is metabolized into a vast spectrum of metabolites. The potential immunosuppressive action of CsA's metabolites has been studied extensively in the early 1990's, with conflicting and inconclusive results. Since then, the pharmacological and clinical consensus guidelines recommend the use of specific monoclonal assays for measurement of CsA's concentrations thus avoiding metabolite interference. Nevertheless, clinical benefit or superiority of these assays was never convincingly demonstrated. We provide a review of the performed in vivo, in vitro and animal studies and their conclusions. During the last years, many transplantation centres have employed the C2 monitoring of CsA (2 hours post-dose concentration). The metabolites / parent drug ratio two hours post dose is completely different from trough levels (predose concentration). Cyclosporine exerts its immunosuppressive action by inhibiting the enzyme calcineurin phosphatase (CaN). Currently, our laboratory, among others, is working on determination of the enzyme's inhibition and its potential use as a pharmacodynamic biomarker. Utilizing this novel pharmacodynamic approach, we have performed in vitro and in vivo studies investigating the immunosuppressive impact of CsA's metabolites on C2 monitoring and on various monitoring assays (mono-/polyclonal). Interestingly, even though we have estimated in vivo that the potential immunosuppressive action of metabolites is less than 10% of the parent drug, we have found assays that take metabolites into consideration to correlate stronger with calcineurin phosphatase inhibition. We believe that the old controversial issue of metabolite induced immunosuppressive action examined under the light of newer pharmacodynamic approaches is still intriguing. Instead of a priori neglecting CsA's metabolites maybe we should investigate the potential of utilizing them as an additional tool towards better therapeutic drug monitoring of cyclosporine.

Generalized epilepsies are a large group of epilepsies with different clinical aspects and prognosis. Many antiepileptic drugs are available for the treatment of these seizures. This paper reviews the evidence relating to the treatment of this group of epilepsies. Historically, the great majority of patients have been treated with “old” anticonvulsant drugs. Over recent years, there has been a marked improvement in the pharmacological armamentarium of physicians. Today, “new” antiepileptic drugs, such as lamotrigine, levetiracetam, topiramate and zonisamide are useful tools in the treatment of pharmacoresistant epilepsies.