By I. Curtis. California State University, Sacramento. 2018.
Bradycardia develops as a result of the block of cardiac sodium channels and the depression of pacemaker activity cheap cytoxan 50 mg. Hypotension develops from arteriolar dilation and decreased cardiac contractility buy 50mg cytoxan otc. These reactions are usually associated with ester-type drugs such as procaine that are metabolized to derivatives of para-aminobenzoic acid buy cytoxan 50mg without a prescription. Long-term use may lead to the development of tolerance and to the development of psycho- logic or physical dependence, or both. Complications related to parenteral drug administration under unsterile conditions or to the coadministration of adulterants are extremely common (e. Drug abuse is the nonmedical, self-administered use of a drug that is harmful to the user. Drug addiction is a nonmedical term that refers to the drug abuser’s overwhelming preoccupa- tion with the procurement and use of a drug. Tolerance is the decreased intensity of a response to a drug following its continued administra- tion. Metabolic tolerance (pharmacokinetic tolerance): The rate of drug elimination increases with long-term use because of stimulation of its own metabolism (autometabolism). Cellular tolerance (pharmacodynamic tolerance): Biochemical adaptation or homeostatic adjustment of cells to the continued presence of a drug. Tolerance to one drug confers at least partial tolerance to other drugs in the same drug class (e. Tolerance is often, but not always, associated with the development of physical dependence. The degree of tolerance varies considerably among different classes of drugs of abuse (e. Psychologic dependence: Overwhelming compulsive need to take a drug (drug-seeking behavior) to maintain a sense of well-being. Psychologic dependence may be related to Chapter 5 Drugs Acting on the Central Nervous System 137 increased dopamine activity in the ‘‘brain reward system’’ (includes the mesolimbic dopa- minergic pathway from the ventral midbrain to the nucleus accumbens and other limbic structures including the prefrontal cortex and limbic and motor systems). Development of psychologic dependence generally precedes development of physical dependence but does not necessarily lead to it. Physical dependence: A latent hyperexcitability that is revealed when administration of a drug of abuse is discontinued after its long-term use (‘‘abstinent withdrawal’’). The severity of the withdrawal syndrome is directly related to the dose of the drug, how long it is used, and its rate of elimination. Cross-dependence: Ability of one drug to substitute for another drug in the same drug class to maintain a dependent state or to prevent withdrawal (e. It may be related to changes in membrane fluidity with changes in membrane protein functions, particu- larly signaling pathways. Respiratory support and avoidance of aspiration of vomitus may be sufficient, but the patient may also require restoration of fluid and electro- lyte balance, thiamine to prevent Wernicke-Korsakoff syndrome, and treatment of hypoglycemia.
The outer surface has a far higher fluoride content than the rest of the enamel so that even a slight nick of the intact surface will remove this reservoir of fluoride safe cytoxan 50mg. Additionally discount 50mg cytoxan overnight delivery, it has been shown that early lesions that remineralize are less susceptible to caries than intact surfaces and these areas of the tooth are all too easily removed when preparing an adjacent tooth cheap 50mg cytoxan visa. It is virtually impossible to avoid damaging the interdental papillae when treating approximal caries. The papillae can be protected by using rubber dam and/or wedges and if well-fitting restorations are placed the tissues will heal fairly rapidly, but long-term damage can be more critical. Many adults can be seen to be suffering from overenthusiastic treatment of approximal caries in their youth; and while the relative import-ance of poor margins compared to bacterial plaque can be debated, the potential damage from approximal restorations is sufficient reason to avoid treatment unless a definite indication is present. Poor restoration of the teeth can, over time, lead to considerable alteration of the occlusion. However, this can allow the teeth to erupt into contact again or the interocclusal position to change and alter the occlusion. Often this is felt to be of little concern, but there are a large number of adults where the cumulative effect of many poorly restored teeth has severely disturbed the occlusion, thus making further treatment difficult, time consuming, and expensive. Even when coarse criteria such as those developed for the United Kingdom Child Dental Health Surveys are used, there is wide variation between examiners. It is not just variations between examiners that need to be considered as there is also a marked difference between the same examiner on different occasions. The implications need to be considered in relation to the decision to treat or not. Caries usually progresses relatively slowly, although some individuals will show more rapid development than others. The majority of children and adolescents will have a low level of caries and progress of carious lesions will be slow. In general, the older the child at the time that the caries is first diagnosed the slower the progression of the lesion. In addition, it is now accepted that the chief mechanism whereby fluoride reduces caries is by encouraging remineralization, and that the remineralized early lesion is more resistant to caries than intact enamel. Although it is difficult to show reversal of lesions on radiographs, many studies have demonstrated that a substantial proportion of early enamel lesions do not progress over many years. Surveys of dental treatment have often shown a rather disappointing level of success. In general, 50% of amalgam restorations in permanent teeth can be expected to fail during the 10 years following placement.
Holding sensitive information on some- one’s genetic make-up raises questions of privacy and security and ethical dilemmas in disease prognosis and treatment choices cheap 50 mg cytoxan amex. After all discount cytoxan 50mg visa, polymorphisms relevant to drug response may overlap with disease susceptibility buy 50mg cytoxan with mastercard, and divulging such informa- tion could jeopardize an individual. On the other hand, legal issues may force the inclusion of pharmacogenomics into clinical practice. Once the genetic component of a severe adverse drug effect is documented, doctors may be obliged to order the genetic test to avoid malpractice litigation. Pharmacoepigenomics vs Pharmacogenetics in Drug Safety Phamacoepigenomics refers to drug action as inﬂuenced by the epigenome, which is the overall epigenetic state of a cell, and serves as an interface between the envi- ronment and the genome. The role of epigenetic factors in drug action has been mentioned throughout this report. The epigenome is dynamic and responsive to environmental signals not only during development, but also throughout life; and it is becoming increasingly apparent that chemicals can cause changes in gene expres- sion that persist long after exposure has ceased. A hypothesis has been presented, which states that commonly-used pharmaceutical drugs can cause such persistent epigenetic changes (Csoka and Szyf 2009). An example of an indirectly acting drug is isotretinoin, which has transcription factor activity. A two-tier mechanism is Universal Free E-Book Store 146 4 Pharmacogenetics postulated for indirect effects in which acute exposure to a drug inﬂuences signaling pathways that may lead to an alteration of transcription factor activity at gene promoters. This stimulation results in the altered expression of receptors, signaling molecules, and other proteins necessary to alter genetic regulatory circuits. Therefore, any epigen- etic side-effect caused by a drug may persist after the drug is discontinued. It is further proposed that some iatrogenic diseases such as tardive dyskinesia and drug- induced systemic lupus erythematosus are epigenetic in nature. If this hypothesis is correct the consequences for modern medicine are profound, since it would imply that our current understanding of pharmacology is an oversimpliﬁcation. Thus epi- genetic side-effects of pharmaceuticals may be involved in the etiology of heart disease, cancer, neurological and cognitive disorders, obesity, diabetes, infertility, and sexual dysfunction. It is suggested that a systems biology approach employing microarray analyses of gene expression and methylation patterns can lead to a better understanding of long-term side-effects of drugs, and that in the future, epigenetic assays should be incorporated into the safety assessment of all pharmaceutical drugs. The impact of pharmacoepigenomics may be equal to or greater than that of pharmacogenetics.