Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026837 (muscle rigidity)
 1,077 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

'Designer drugs' are substances intended for recreational use which are derivatives of approved drugs so as to circumvent existing legal restrictions. The term as popularised by the lay press lacks precision. Contrary to the popular belief that 'designer drugs' are original creations, the majority of these agents are 'borrowed' from legitimate pharmaceutical research. They merely represent the most recent developments in the evolution of mind-altering chemicals. The most extensively studied class of psychoactive compounds is the phenylethylamines (mescaline analogues). This class includes catecholamines, therapeutic agents and numerous illicit derivatives. Subtle alterations of the phenylethylamine molecule give rise to a spectrum of pharmacological properties ranging from pure sympathomimetic stimulation to primarily psychoactive effects. Although most of these compounds are only of historical interest, amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxymethamphetamine (MDMA) continue to be used recreationally. Many deaths have been ascribed to this class of compounds. In overdose the differences between these compounds blur and the clinical presentation is similar to that of amphetamine overdose characterised by tachycardia, hypertension, hyperthermia, diaphoresis, mydriasis, agitation, muscle rigidity, and hyper-reflexia. Death usually results from arrhythmias, hyperthermia or intracerebral haemorrhage. Treatment is aggressive and supportive with careful attention to temperature, blood pressure and seizure control. Synthetic opioid derivatives, which represent the second major class of 'designer drugs', are derivatives of fentanyl (e.g. alpha-methylfentanyl, 3-methylfentanyl) or pethidine (meperidine) and are extremely potent compounds responsible for numerous overdose deaths. Attempts to synthesise pethidine have resulted in the accidental production of MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), a compound which is metabolised in the brain by the monoamine oxidase system to a toxic intermediate (MPP+) which selectively destroys the sustantia nigra, resulting in the rapid onset of severe Parkinsonian symptoms. Naloxone will antagonise the opiate effects of this drug class, although high doses may be required. Arylhexylamines constitute the third class of 'designer drugs'. The predominant member of this class is phencyclidine (PCP), a derivative of the anaesthetic ketamine. This unique class of psychoactive agents exhibits broad and complex pharmacological effects.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:'Designer drugs'. A problem in clinical toxicology. 328 24

Parkinson's disease is a progressive neurodegenerative condition of unknown cause and with no known cure. The diagnosis is based on clinical findings of rest tremor, muscle rigidity, bradykinesia, and gait instability. Over 40% of patients develop a dementia syndrome that is largely distinct from Alzheimer's disease. Depression is common, also occurring in more than 40% of patients with PD. Careful evaluation in necessary to help distinguish Parkinson's disease from secondary causes of parkinsonism. Carbidopa/levodopa, dopamine agonists, and monoamine oxidase type B inhibitors are the mainstays of treatment. Anticholinergics and other agents may also be useful. Pharmacologic treatment must be carefully titrated to control symptoms and to avoid side effects. In advanced disease, dose-related dyskinesias, end-of-dose wearing-off effect, and unpredictable sudden motor fluctuations become very disabling and difficult to manage.
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PMID:Parkinson's disease: making the diagnosis, selecting drug therapies. 792 45

A 48-year-old man presented to the emergency department with confusion, agitation, diaphoresis, and muscle rigidity after beginning treatment with fluoxetine, a serotonin reuptake inhibitor. He had discontinued treatment with tranylcypromine, a monoamine oxidase inhibitor, 2 weeks earlier. The constellation of findings was diagnostic of the serotonin syndrome.
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PMID:Fluoxetine and the serotonin syndrome. 797 79

Antidepressant drugs are among the most commonly encountered causes of self-poisoning. These drugs include tricyclics, tetracyclics, bicyclics and monocyclics, as well as monoamine oxidase (MAO) inhibitors and selective serotonin reuptake inhibitors (SSRIs). Of these, the tricyclic antidepressants (TCAs) are generally more toxic in overdose, with major toxicity usually manifesting within the first 6 hours after overdose. Various studies indicate that patients at risk of toxicity from TCA overdose may be identified by neurological, cardiovascular and electrocardiography status, together with a quantitative estimate of the plasma drug concentration. While there are various methods available for such chemical estimations, the most satisfactory appears to be fluorescence polarisation immunoassay which gives rapid quantitative results for a variety of TCAs. The selective MAO-A inhibitor antidepressants and the SSRIs are relatively nontoxic when taken alone. However, overdoses of combinations of MAO inhibitors and either SSRIs or TCAs with serotonin reuptake blocking activity may result in a serotonin syndrome with a severe or fatal outcome. Features of this syndrome include hyperpyrexia, disseminated intravascular coagulation, convulsions, coma and muscle rigidity, which may not develop until 6 to 12 hours after overdose. While quantitative chemical identification of these drugs following overdose is helpful in confirming the diagnosis, it is not mandatory. The increasing use of MAO-A inhibitors and SSRIs in the treatment of depression suggests that careful clinical observation is required when combination overdoses are suspected.
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PMID:Antidepressant toxicity and the need for identification and concentration monitoring in overdose. 852 78

Excessive stimulation of serotonin 5HT1A receptors causes a syndrome of serotonin excess that consists of shivering, muscle rigidity, salivation, confusion, agitation and hyperthermia. The most common cause of this syndrome is an interaction between a monoamine oxidase inhibitor (MAOI) and a specific serotonin reuptake inhibitor. Venlafaxine is a new antidepressant agent that inhibits the reuptake of serotonin and norepinephrine. We report a venlafaxine-MAOI interaction that resulted in the serotonin syndrome in a 23-y-old male who was taking tranylcypromine for depression. He had been well until the morning of presentation when he took 1/2 tab of venlafaxine. Within 2 h he became confused with jerking movements of his extremities, tremors and rigidity. He was brought directly to a hospital where he was found to be agitated and confused with shivering, myoclonic jerks, rigidity, salivation and diaphoresis. His pupils were 7 mm and sluggishly reactive to light. Vital signs were: blood pressure 120/67 mm Hg, heart rate 127/min, respiratory rate 28/min, and temperature 97 F. After 180 mg of diazepam i.v. he remained tremulous with muscle rigidity and clenched jaws. He was intubated for airway protection and because of hypoventilation, and was paralyzed to control muscle rigidity. His subsequent course was remarkable for non-immune thrombocytopenia which resolved. The patient's maximal temperature was 101.2 F and his CPK remained < 500 units/L with no other evidence of rhabdomyolysis. His mental status normalized and he was transferred to a psychiatry ward. This patient survived without sequelae due to the aggressive sedation and neuromuscular paralysis.
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PMID:Serotonin syndrome from venlafaxine-tranylcypromine interaction. 888 41

Parkinson's disease (PD) is a slowly progressing neurologic movement disorder affecting nearly 1% of the population over age 65. PD is the fourth most common neurodegenerative disease of patients. Incidence is greater in men with a ratio of 3:2--men to women. Because PD is so complex, diagnosis and treatment are often very challenging. While the cause of PD is unknown, research has concentrated on genetics, exogenous toxins, and endogenous toxins from cellular oxidative reactions. The presenting symptoms of a patient with PD include muscle rigidity, tremors, bradykinesia, and postural instability. Treatment for PD has been primarily pharmacologic: levodopa, carbidopa, anticholinergics, and selegiline (a monoamine oxidase inhibitor to reestablish an equilibrium between dopamine and acetylcholine). surgical procedures (e.g., pallidotomy, thalamotomy, and tissue implants) are a possible choice of treatment for patients who have failed to respond satisfactorily to drugs.
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PMID:Pathophysiology, assessment, and treatment of Parkinson's disease. 925 16

Two cases of poisoning with moclobemide are presented. Moclobemide is a reversible inhibitor of the monoamine oxidase type A (RIMA). Intoxication with moclobemide is according to previously published case stories benign. Both patients described presented severe symptoms, such as convulsions, coma, muscle rigidity and respiratory failure. One of the patients, a 37-year-old woman, also suffered cardiovascular collapse and elevated body temperature (more than 41.9 degrees C), which was treated successfully with dantrolene and norepinephrine. The symptoms match the diagnostic criteria for serotonin syndrome. The possible reasons why the two patients suffered life-threatening complications and the treatment of serotonin syndrome are discussed.
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PMID:[Poisoning with a reversible and selective monoaminooxidase inhibitor]. 927 60

The traditional view of opioids held that the individual opioid agonists shared the same mechanism of action, differing only in their potency and pharmacokinetic properties. However, recent advances in opioid receptor pharmacology have made this view obsolete. Distinguishing features of the synthetic opioid agonists are related, at least in part, to variation in affinity and intrinsic efficacy at multiple opioid receptors. Respiratory depression is the opioid adverse effect most feared by anaesthesiologists. Specific kappa-receptor agonists produce analgesia with little or no respiratory depression. There are a number of commercially available kappa-receptor partial agonist drugs, the so-called agonist-antagonist or nalorphine-like opioids, which appear to have a limited effect on breathing. Within the series of fentanyl analogues there are differences in behaviour towards particular opioid receptors and there is evidence for subtle differences in respiratory depressant effects. Pethidine (meperidine) causes histamine release and myocardial depression, while the fentanyl analogues do not. Pethidine has atropine-like effects on heart rate, while fentanyl analogues reduce heart rate by a vagomimetic action. Severe bradycardia or even asystole is possible with fentanyl analogues, especially in conjunction with the vagal stimulating effects of laryngoscopy. Fentanyl analogues often produce minor reductions in blood pressure, and occasionally severe hypotension by centrally mediated reduction in systemic vascular resistance. Muscle rigidity and myoclonic movement occurs frequently during induction of anaesthesia with larger doses of opioids. Fentanyl and alfentanil have been reported to produce localised temporal lobe electrical seizure activity in patients with complex partial epilepsy. There are probably fewer biliary effects with agonist-antagonist opioids than the agonist opioids. The mechanism of adverse effects after spinal administration is distinctly different for morphine, which is very water soluble, compared with more lipid-soluble opioids. The systemic absorption of morphine after intrathecal or epidural administration is very slow, resulting in long duration of analgesia and low plasma concentrations, while lipid-soluble opioids are rapidly absorbed into the circulation and redistributed to the brain. The serotonin syndrome may result from coadministration of pethidine, dextromethorphan, pentazocine or tramadol with monoamine oxidase inhibitors (MAOIs) or selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors (SSRIs). There are clinically important interactions between opioids and hypnosedatives, resulting in synergistic effects on sedation, breathing and blood pressure.
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PMID:Adverse effects of opioid agonists and agonist-antagonists in anaesthesia. 974 65

The effect of single and multiple 1-methyl-1,2,3,4-tetrahydroisoquinoline (1MeTIQ) and 1-benzyl-1,2,3,4-tetrahydroisoquinoline (1BnTIQ) administration on concentrations of dopamine and its metabolites: homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) and 3-methoxytyramine (3MT) in three brain areas was studied HPLC with electrochemical detection in Wistar rats. The rate of dopamine catabolism in the striatum along the N-oxidative and O-methylation pathways was assessed by calculation of the ratio of appropriate metabolites to dopamine concentration. In addition, the spontaneous and apomorphine-stimulated locomotor activity, and muscle rigidity was studied after acute administration of 1MeTIQ and 1BnTIQ. We have found that 1MeTIQ did not change the level of dopamine and HVA in all investigated structures both after a single and chronic administration. However, the levels of intermediary dopamine metabolites, DOPAC and 3MT, were distinctly affected. The level of DOPAC was strongly depressed (by 60-70%) while the level of extraneuronal matabolite 3MT was significantly elevated (by 170-200%). In contrast to 1MeTIQ, 1BnTIQ depressed the level of dopamine (by approximately 60%) and increased the level of total metabolite, HVA, (by 40%) especially in the striatum, but the levels of DOPAC and 3MT remained unchanged. The paper has shown that 1MeTIQ and 1BnTIQ produced different effects on dopamine catabolism. Potential neuroprotective compound 1MeTIQ did not change the rate of total dopamine catabolism, it strongly inhibited the monoamine oxidase (MAO)-dependent catabolic pathway and significantly activated the catechol-O-methyltransferase (COMT)-dependent O-methylation. In contrast 1BnTIQ, a compound with potential neurotoxic activity, produced the significant increase of the rate of dopamine metabolism with strong activation of the oxidative MAO-dependent catabolic pathway. Interestingly, both compounds produced similar antidopaminergic functional effects: antagonism of apomorphine hyperactivity and induction of muscle rigidity. The results may explain the biochemical basis of the neuroprotective and of the neurotoxic properties endogenous brain tetrahydroisoquinoline derivatives.
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PMID:Different action on dopamine catabolic pathways of two endogenous 1,2,3,4-tetrahydroisoquinolines with similar antidopaminergic properties. 1143 77

Excess serotonin in the central nervous system leads to a condition commonly referred to as the serotonin syndrome, but better described as a spectrum of toxicity - serotonin toxicity. Serotonin toxicity is characterised by neuromuscular excitation (clonus, hyperreflexia, myoclonus, rigidity), autonomic stimulation (hyperthermia, tachycardia, diaphoresis, tremor, flushing) and changed mental state (anxiety, agitation, confusion). Serotonin toxicity can be: mild (serotonergic features that may or may not concern the patient); moderate (toxicity which causes significant distress and deserves treatment, but is not life-threatening); or severe (a medical emergency characterised by rapid onset of severe hyperthermia, muscle rigidity and multiple organ failure). Diagnosis of serotonin toxicity is often made on the basis of the presence of at least three of Sternbach's 10 clinical features. However, these features have very low specificity. The Hunter Serotonin Toxicity Criteria use a smaller, more specific set of clinical features for diagnosis, including clonus, which has been found to be more specific to serotonin toxicity. There are several drug mechanisms that cause excess serotonin, but severe serotonin toxicity only occurs with combinations of drugs acting at different sites, most commonly including a monoamine oxidase inhibitor and a serotonin reuptake inhibitor. Less severe toxicity occurs with other combinations, overdoses and even single-drug therapy in susceptible individuals. Treatment should focus on cessation of the serotonergic medication and supportive care. Some antiserotonergic agents have been used in clinical practice, but the preferred agent, dose and indications are not well defined.
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PMID:Serotonin toxicity: a practical approach to diagnosis and treatment. 1787 86


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