Phenobarbital is an anticonvulsive drug widely used in newborns with hypoxic-ischemic encephalopathy. The objective of our study was to describe possible effect of frequently co-administered medications (dopamine, dobutamine, norepinephrine, furosemide, phenytoin, and analgesics) on the phenobarbital pharmacokinetics in full term newborns with hypoxic-ischemic encephalopathy. Phenobarbital pharmacokinetic parameters (standardized intravenous loading dose was 10-20 mg/kg, maintenance dose 2-6 mg/kg/day) were computed using non-compartmental analysis. Co-medication was evaluated throughout the whole treatment period up to 5 days. Volume of distribution, clearance, and half-life median values (95 % CI) for phenobarbital in the whole study population (n=37) were 0.48 (0.41-0.56) l/kg, 0.0034 (0.0028-0.0040) l/h/kg, and 93.7 (88.1-99.2) h, respectively. Phenobarbital pharmacokinetic parameters were not significantly affected by vasoactive drugs (dopamine, dobutamine, and norepinephrine), furosemide, phenytoin, or analgesics. Furthermore, no dose-dependent alteration of phenobarbital pharmacokinetic parameters was noted for vasoactive medication at doses equivalent to cumulative vasoactive-inotropic score (area under the curve in a plot of vasoactive-inotropic score against time) 143.2-8473.6, furosemide at cumulative doses of 0.2-42.9 mg/kg, or phenytoin at cumulative doses of 10.3-46.2 mg/kg. Phenobarbital pharmacokinetics was not affected by investigated co-administered drugs used in newborns with hypoxic-ischemic encephalopathy in real clinical settings., M. Šíma, P. Pokorná, K. Hronová, O. Slanař., and Obsahuje bibliografii
Chronické onemocnění ledvin patří k nejběžnějším klinickým problémům, často však poddiagnostikovaným. Snížení renální funkce vede k ovlivnění všech farmakokinetických vlastností léčiv, nemocní s chronickým onemocněním ledvin jsou proto ve zvýšené míře ohroženi nežádoucími účinky farmakoterapie – především předávkováním léky, které jsou primárně vylučovány ledvinami. Dalšími zásadními problémy u pacientů s onemocněním ledvin jsou polymorbidita a léková polypragmazie. Před nasazením každého nového léčiva je nutné především určit glomerulární filtraci, přičemž samotné stanovení hladiny sérového kreatininu není spolehlivým indikátorem očišťovací funkce ledvin. U léků eliminovaných převážně nebo výhradně ledvinami se dávkovací schéma upravuje snížením dávky léku, prodloužením intervalu mezi podáním jednotlivých dávek nebo kombinací obou metod., Chronic kidney disease belongs among the most frequent clinical problems, but often remains underdiagnosed. Decreased renal function affects all pharmacokinetic properties of drugs. Thus, patients with chronic kidney disease are at increased risk of adverse drug effects – especially overdoses of drugs that are primarily eliminated by the kidneys. Other frequent problems in patients with kidney disease are polymorbidity and polypharmacy. Before using any new medication, determination of the glomerular filtration rate is obligatory, since the value of serum creatinine alone is not a reliable indicator of kidney function. The dosing of drugs eliminated mainly or solely by the kidneys can be adjusted by reducing the dose, prolonging the interval between doses, or combining both these methods., and Zakiyanov O., Vachek J., Tesař V.
Ve své práci přinášíme obecný pohled na farmakokinetické interakce antiepileptik ve stáří i jejich konkrétní příklady. Starší nemocní bývají léčeni pro více diagnóz a zpravidla užívají několik léků zároveň. Antiepileptika (AE) jsou těmto pacientům ordinována častěji, než se všeobecně soudí. Některá AE mají větší tendenci ke vzniku interakcí. Může tak dojít ke snížení účinnosti samotného AE nebo léku podávaného v kombinaci. V úvodu se podrobněji zaměřujeme na změny farmakokinetiky během stárnutí, které vysvětlují větší citlivost seniorů k lékovým interakcím. Níže jsou popsány zcela základní principy interakcí a faktory, které je mohou ovlivnit. Další text je věnován farmakokinetickým interakcím mezi jednotlivými AE a mezi AE a dalšími léky v kombinaci. Interakce mezi AE jsou znázorněny přehlednou formou v tabulce a s jednoduchým příkladem. Interakce s dalšími léky jsou uvedeny podrobně, v řazení podle zjednodušených skupin léků, a s přihlédnutím k jejich možné klinické relevanci. Na závěr je článek doplněn 2 kazuistikami farmakokinetických interakcí u našich starších pacientů s epilepsií, The article presents a general view of antiepileptic drug interactions in old age and their specific examples. Elderly patients often receive treatment for different diagnoses and take different drugs at the same time. Antiepileptic drugs (AEDs) are prescribed to such patients more often than generally believed. Some AEDs are more prone to interactions. This may result in a lower effect of a specific AED or of the drug administered in combination with it. The introductory part of the article focuses on the pharmacokinetic changes associated with ageing which are accountable for higher sensitivity of seniors to drug interactions. The text continues with a description of the basal principles of interactions and of the factors by which they can be influenced. The subsequent text deals with pharmacokinetic interactions between the different AEDs and between AEDs and other drugs with which they are combined. Interactions between AEDs are shown schematically in a table, including simple examples. Interactions with other drugs are shown in detail and in an order corresponding to simplified groups of drugs, with regard to their potential clinical relevance. The final part of the paper contains 2 case studies of pharmacokinetic interactions in our elderly patients with epilepsy., Tomáš Nežádal, Jiří Hovorka, Markéta Janicadisová, Michal Bajaček, and Lit.: 47
Polymorphic CYP2D6 is the enzyme that activates the opioid analgesic tramadol by O-demethylation to its active metabolite O-demethyltramadol (M1). Our objective was to determine the opioid effects measured by pupillary response to tramadol of CYP2D6 genotyped volunteers in relation to the disposition of tramadol and M1 in plasma. Tramadol displayed phenotypic pharmacokinetics and it was possible to identify poor metabolizers (PM) with >99 % confidence from the metabolic ratio (MR) in a single blood sample taken between 2.5 and 24 h post-dose. Homozygous extensive metabolizers (EM) differed from PM subjects by an almost threefold greater (P=0.0014) maximal pupillary constriction (Emax). Significant correlations between the AUC and Cmax values of M1 versus pupillary constriction were found. The corresponding correlations of pharmacokinetic parameters for tramadol itself were weaker and negative. The strongest correlations were for the single-point metabolic ratios at all sampling intervals versus the effects, with rs ranging from 0.85 to 0.89 (p‹0.01). It is concluded that the concept of dual opioid/non-opioid action of the drug, though considerably stronger in EMs, is valid for both EM and PM subjects. This is the theoretical basis for the frequent use and satisfactory efficacy of tramadol in clinical practice when given to genetically non-selected population., O. Slanař, M. Nobilis, J. Květina, R. Mikoviny, T. Zima, J. R. Idle, F. Perlík., and Obsahuje biblografii a bibliografické odkazy
Pulse dye densitometry (PDD) enables the evaluation of hemodynamic state as well as liver function. A repeated examination, even after a short pause (or under stress condition), enables to follow safely the dynamics of liver pathology. From presented parameters we have evaluated as reliable the C5-clearance, an expression of equilibrium state in the two compartment liver system. Furthermore, T-index expresses ratio of C5 value to cardiac output, it is a sensitive indicator of the blood pole, i.e. sinusoidal uptake, which is in very good correlation with staging of hepatopathies. The isolated h constant in correlation to T-index is valuable For functional grading. The Japanese automatic analyzer of indocyanine green (ICG) dilution and elimination curves, after incorporation of a two compartment mathematical mode l, becomes more useful for complex hepatological diagnostics. Non-invasive PDD is becoming of uppermost importance to clinic al interest, yielding comparable results as other complicated and invasive examinations and may be, therefore, repeated in short time intervals for different indications with minimal stress of examined patient., J. A. Tichý ... [et al.]., and Obsahuje seznam literatury
Pharmacokinetics of leptin in mammals has received limited attention and only one study has examined more than two time points and this was in ob/ob mice. This study is the first to observe the distribution of leptin over a time course in female mice. A physiologic dose (12 ng) of radiolabelled leptin was injected in adult female mice via the lateral tail vein and tissues were dissected out and measured for radioactivity over a time course up to two hours. Major targets for administered leptin included the liver, kidneys, gastrointestinal tract and the skin while the lungs had high concentrations of administered leptin per gram of tissue. Leptin was also found to enter the lumen of the digestive tract intact from the plasma. Very little of the dose (<1 %) was recovered from the brain at any time. Consequently we confirm that the brain is not a major target for leptin from the periphery, although it may be very sensitive to leptin that does get to the hypothalamus. Several of the major targets (GI tract, skin and lungs) for leptin form the interface for the body with the environment, and given the ability of leptin to modulate immune function, this may represent a priming effect for tissues to respond to damage and infection., R. A. Hart, R. C. Dobos, L. L. Agnew, R. L. Tellam, J. R. McFarlane., and Obsahuje bibliografii