By F. Karlen. Fuller Theological Seminary.
One drug substrate can Also buy discount levlen 0.15mg online, since water constitutes a larger percentage of compete for transport with a simultaneously adminis- the total body weight of the newborn than of individu- tered or endogenous similarly charged compound; this als in other age groups generic levlen 0.15mg overnight delivery, the apparent volume of distri- competition will decrease the overall rate of excretion bution of water-soluble drugs is greater in neonates. The secretory capacity of both the or- This results in a lower concentration of drug in the ganic anion and organic cation secretory systems can be blood coming to the kidneys per unit of time and hence saturated at high drug concentrations. Peritubular side Luminal side (plasma) (ultrafiltrate) Passive Diffusion An important determinant of the urinary excretion of Organic OA pool OA drugs (i. In general, the movement of drugs is favored from the tubular lumen to blood, partly because of the reabsorption of water that occurs throughout most portions of the nephron, which results in an increased concentration of drug in the luminal Active transport ﬂuid. The concentration gradient thus established will Passive transport facilitate movement of the drug out of the tubular lu- men, given that the lipid solubility and ionization of the FIGURE 4. Hence, a reduction in se- lar secretion may be metabolized to compounds that cretory activity does not reduce the excretory process to are. This is often true for metabolites that are formed as zero but rather to a level that approximates the a result of conjugative reactions. Some substances ﬁltered at the glomerulus are reab- These active secretory systems are important in sorbed by active transport systems found primarily in drug excretion because charged anions and cations are the proximal tubules. Active reabsorption is particularly often strongly bound to plasma proteins and therefore important for endogenous substances, such as ions, are not readily available for excretion by ﬁltration. The the active secretory systems can rapidly and efﬁciently probable location of the active transport system is on remove many protein-bound drugs from the blood and the luminal side of the proximal cell membrane. Bidirectional active transport across the proximal Any drug known to be largely excreted by the kid- tubule also occurs for some compounds; that is, a drug ney that has a body half-life of less than 2 hours is prob- may be both actively reabsorbed and secreted. Several pharmacologically active urate is probably reabsorbed, whereas that eventually drugs, both anions and cations, known to be secreted are found in the urine is mostly derived from active tubular listed in Table 4. It is important to appreciate that these tubular Most drugs act by reducing active transport rather transport mechanisms are not as well developed in the than by enhancing it. In addition, their functional ca- loss (uricosuric agents, such as probenecid and sulﬁn- pacity may be diminished in the elderly. Thus, com- pyrazone) probably inhibit active urate reabsorption, pounds normally eliminated by tubular secretion will be while pyrazinamide, which reduces urate excretion, may excreted more slowly in the very young and in the older block the active tubular secretion of uric acid. This age dependence of the rate of renal drug se- plicating observation is that a drug may primarily in- cretion may have important therapeutic implications hibit active reabsorption at one dose and active secre- and must be considered by the physician who prescribes tion at another, frequently lower, dose. The transport Prostaglandins Neostigmine mechanism is in the luminal portion of the membrane of the Salicylate Quinine proximal tubular cell. This is drugs pass through the hepatocyte membrane by diffu- offered as an explanation for the apparently paradoxi- sion. The subsequent passage of substances into the bile, cal effects of low and high doses of drugs on the total however, is much more selective. Compounds of group A are those whose concentration in bile and plasma are almost identical (bile–plasma ra- tio of 1). Extent of active tubular secretion of the com- However, biliary excretion plays a major role (5–95% of pound the administered dose) in drug removal for some an- 5. Possibly, extent of active tubular reabsorption ions, cations, and certain un-ionized molecules, such as cardiac glycosides. In addition, biliary elimination may Changes in any of these factors may result in clini- be important for the excretion of some heavy metals. In the ﬁnal Cardiac glycosides, anions, and cations are trans- analysis, the amount of drug that ﬁnally appears in the ported from the liver into the bile by three distinct and urine will represent a balance of ﬁltered, reabsorbed independent carrier-mediated active transport systems, (passively and actively), and secreted drug. For many the last two closely resembling those in the renal proxi- drugs, the duration and intensity of pharmacological ef- mal tubules that secrete anions and cations into tubular fect will be inﬂuenced by the status of renal function, urine. As is true for renal tubular secretion, protein- because of the major role played by the kidneys in drug bound drug is completely available for biliary active and metabolite elimination. Thus, the ability cleared by the kidney, and the potential for drug toxic- of certain compounds to be actively secreted into bile ity, especially if renal function is reduced. On the other hand, most drugs that are secreted by Biliary Excretion the liver into the bile and then into the small intestine The liver secretes about 1 L of bile daily. The physicochem- composition depend on the secretory activity of the he- ical properties of most drugs are sufﬁciently favorable patic cells that line the biliary canaliculi. As the bile for passive intestinal absorption that the compound will ﬂows through the biliary system of ducts, its composi- reenter the blood that perfuses the intestine and again tion can be modiﬁed in the ductules and ducts by the be carried to the liver. Such recycling may continue (en- processes of reabsorption and secretion, especially of terohepatic cycle or circulation) until the drug either un- electrolytes and water. For example, osmotically active dergoes metabolic changes in the liver, is excreted by compounds, including bile acids, transported into the the kidneys, or both.
Lamivudine Treatment is most effective if begun within 3 days of the Lamivudine is a synthetic cytidine analogue used in the onset of symptoms buy levlen 0.15 mg visa. Its acti- Although ribavirin monotherapy is ineffective vation requires phosphorylation by cellular enzymes order levlen 0.15 mg free shipping. Intravenous ribavirin may be useful in the ther- mammalian DNA polymerases with a much lower po- apy of Hantaan virus infection, Crimean or Congo virus tency. Mutations in the DNA Adverse Effects, Contraindications, polymerase of HBV are associated with decreased and Drug Interactions lamivudine efﬁcacy and have been documented in pa- tients treated with this agent for 6 months or more. Pulmonary function may decline if aerosol rib- Absorption, Metabolism, and Excretion avirin is used in adults with chronic obstructive lung dis- ease or asthma. Deterioration of pulmonary and cardio- Lamivudine is rapidly absorbed from the gastrointesti- vascular function has also been seen in severely ill nal tract and has an oral bioavailability of approxi- infants given this preparation. Health care changed by the kidney and has an elimination half-life workers exposed to aerosol ribavirin during its adminis- of 5 to 7 hours. Palivizumab neutralizes RSV and inhibits its ability to fuse with host Lamivudine is indicated for the treatment of HIV when cell membranes. A rived in vitro but have not been found in clinical isolates lower dose than that used to treat HIV is approved for to date. Although lamivudine initially improves histological and biochemical measures of he- Absorption, Metabolism, and Excretion patic function and reduces HBV DNA to below the lim- its of detection, withdrawal of the drug usually results in Palivizumab is administered prophylactically as a disease recurrence. Resistance appears in up to one- monthly intramuscular injection prior to and during third of patients after 1 year of treatment. Elevated alanine children who are younger than 24 months of age and aminotransferase (ALT), serum lipase, and creatine ki- have bronchopulmonary dysplasia or chronic lung dis- nase may also occur. Coadministration of Palivizumab can reduce the incidence of RSV-related trimethoprim–sulfamethoxazole decreases the renal hospitalization by approximately half. Palivizumab Adverse Effects, Contraindications, Palivizumab (Synagis) is a humanized monoclonal anti- and Drug Interactions body directed against the highly conserved A antigenic site of the F protein on the surface of RSV. It contains Serious adverse reactions caused by palivizumab are 95% human and 5% murine antibody sequences and rare. Although no anaphylactoid reactions have been re- Palivizumab is composed of the human framework re- ported to date, the possibility of this reaction exists be- gion of the IgG-1 -chain joined to the antigen-binding cause palivizumab is a protein. Caitlyn Doe is a 24-year-old woman in her third pected to produce a signiﬁcantly higher concentra- month of pregnancy. She has had severe pain, tion of active metabolite in cells infected with its swelling, and redness in both eyes for several days target virus? Which drug is in- (D) Penciclovir dicated for HSV keratoconjunctivitis but is least (E) Lamivudine likely to harm the fetus? Which of the following drugs should not be given in (A) Cidofovir combination with zidovudine because of an in- (B) Docosanol creased risk of myelosuppression? Mitchell Jones, a 35-year-old man, began treatment (D) Famciclovir for hepatitis C with interferon- -2b and ribavirin (E) Zanamivir (Rebetron) 4 weeks ago. On returning to his doctor 582 VI CHEMOTHERAPY Current Values Values Before Treatment Normal Values (cells/ L) (cells/ L) (cells/ L) Erythrocytes 3. His hemoglobin, CBC, differ- its active triphosphate form by host cellular en- ential, and platelet counts are shown in the accom- zymes. Acyclovir is in pregnancy category B: animal (A) Inhibition of a viral enzyme that aids the studies have shown no evidence of harm to the fe- spread of virus through respiratory mucus and is re- tus, but no large, controlled studies of human out- quired for the release of progeny virus comes have been performed. Cidofovir may be used (B) Competitive inhibition of viral DNA poly- to treat HSV that is resistant to acyclovir; however, merase, which leads to early chain termination of it is embryotoxic and teratogenic, and Ms. Docosanol is used for cold sores (C) Stimulation of the tyrosine kinase activity of and is not indicated for ophthalmic use. Fomivirsen the JAK-STAT signal transduction pathway, result- is effective against CMV retinitis, not HSV keratitis. Interferons and ribavirin are both likely to cause for cellular enzymes required for viral replication anemia; the combination of these two agents in- (E) Inhibition of the viral protease required for creases this possibility. Interferons do not stimulate protein processing prior to assembly of progeny lymphocyte proliferation.
HYPNOSIS AS A RESEARCH TOOL We have presented hypnosis both as a tool for affecting change and as a phenomenon in its own right purchase 0.15mg levlen free shipping, including the psychological and physiological components of that phenomenon levlen 0.15mg free shipping. Many have argued for the importance of hypnosis as a research tool—a tool to examine cognitive functioning of normal and pathological conditions—by inducing certain mental states in healthy subjects. Research has challenged conventional models of automatic and obligatory word recognition, by demonstrating reduced SIE when individuals are given suggestions to see the presented words as meaningless characters of a foreign 107 language. Such effects are not due to simple eye defocusing, and research is slowly identifying the specific brain regions involved in hypnotic inhibition of the Stroop 108 effect. The use of hypnosis in memory research has aided in the examination of the 109,110 constructive and reconstructive nature of memories and the nature, structure and 111 function of autobiographical memories. Researchers have also investigated conditions such as conversion hysteria by generating symptoms in healthy subjects using hypnosis. In a single-case PET scan study in which a hypnotized subject was given suggestions for 112 left-leg paralysis, the resultant hypnotic paralysis activated similar brain areas to those 113 found in a similar study of conversion hysteria (leg paralysis). Though not conclusive, there is some indication that conversion disorder patients are more responsive to hypnotic 114 suggestions and research has shown hypnosis to be an effective treatment for various 115 motor-type conversion disorders. With integration of brain mapping techniques, hypnosis is a tool that can readily assist in characterizing discrete cognitive components in neurophysiological terms. Two qualifiers must be made, however: first, identifying brain areas associated with certain tasks or mental phenomena (such as visual hallucinations) does not disqualify that particular brain area from active involvement in other (non-hallucination) tasks; and second, isolating individual components associated with a given task does not provide a complete model of the neurophysiological processes involved with that task—identified brain areas are almost certainly part of a more distributed network of activation. The next step will be to identify the temporal relationship of activation in these distributed components. HYPNOSIS AS A DIAGNOSTIC TOOL Considerable controversy surrounds provocation methods as a tool for differentiating epileptic and non-epileptic seizures. Non-epileptic seizures are reported in 10–23% of patients referred to epilepsy centers. While long-term video-EEG monitoring can commonly be used to detect distinguishing EEG changes accompanying clinical seizures, the expense, duration and accessibility of such techniques often makes it unfeasible. However, the necessary use of deception in such techniques presents certain ethical (and perhaps legal) dilemmas in terms of informed 116,117 consent. In light of this, it has been suggested that hypnotically provoked pseudoseizures can be elicited without the need for deception, and preliminary reports Hypnosis 215 118–120 have shown it to be an effective technique. Regardless of the provocation method used, the induction of a psychogenic seizure does not rule out the possibility of epileptic seizures. Research has shown that between 10–20% of psychogenic seizure patients also have epileptic seizures. However, identification of psychogenic seizures can create 121 improved outlook in patients, and psychotherapeutic interventions (including hypnosis ) have been shown to be effective in the reduction or elimination of seizures in such 122 patients. There are countless certification programs available in the USA, Britain and worldwide. Certification can be obtained from weekend courses, correspondence courses and even through $100. The most important factor in the clinical application of hypnosis is that the practitioner be qualified to treat the presented problem without the use of hypnosis. It is simply one of many tools that may be used by a qualified psychotherapist, dentist, nurse, or physician, when appropriate. Although it is not difficult to learn how to hypnotize someone, using hypnosis appropriately and effectively is a developed skill. In the USA, the Society for Clinical and Experimental Hypnosis (SCEH) and the American Society for Clinical Hypnosis (ASCH) offer specialized training in hypnosis to professionals with appropriate credentials, and both societies offer referral services for those seeking qualified practitioners. The current contact information for these societies, along with the British Society of Experimental and Clinical Hypnosis (BSECH), the British Society of Medical and Dental Hypnosis (BSMDH) and the International Society of Hypnosis (ISH), can be found in the Appendix. In their investigation of Mesmer, the Royal Commission set the bar appropriately high. If we are to argue that hypnosis works, then we must demonstrate this with replicable evidence that can be explained in relation to current understandings of medical and cognitive science. There is now strong empirical support, including brain activation studies, for the use of hypnosis in pain management.
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