By A. Jens. New England Conservatory of Music. 2018.
Mechanism of Action PENICILLINS Beta-lactam antibacterial drugs inhibit synthesis of bacter- ial cell walls by binding to proteins (penicillin-binding pro- The penicillins are effective discount provera 5 mg on line breast cancer jobs, safe purchase provera 2.5 mg amex menstruation full moon, and widely used anti- teins) in bacterial cell membranes. The group includes natural extracts from defective cell wall that allows intracellular contents to leak the Penicillium mold and several semisynthetic derivatives. In sub-bactericidal con- When penicillin G, the prototype, was introduced, it was centrations, the drugs may inhibit growth, decrease viability, (text continues on page 515) 512 SECTION 6 DRUGS USED TO TREAT INFECTIONS Drugs at a Glance: Penicillins Routes and Dosage Ranges Generic/Trade Name Adults Children Penicillins G and V Penicillin G potassium and sodium IM 300,000–8 million U daily IM, IV 50,000–300,000 U/kg/d in divided (Pﬁzerpen) IV 6–20 million U daily by continuous or intermittent doses q4h infusion q2–4h. For direct IV injec- Weight > 40 kg: Same as adults tion, the dose should be well diluted and given Weight ≤ 40 kg: PO, IM, IV 50–100 mg/kg/d in over 10–15 min. In severe infections, Weight > 20 kg: Same as adults (Principen) doses up to 2 g q4h may be given IV. Weight ≤ 20 kg: PO, IM, IV 50–200 mg/kg/d in divided doses q6h Amoxicillin PO 250–500 mg q8h Weight > 20 kg: Same as adults (Amoxil) Weight ≤ 20 kg: 20–40 mg/kg/d in divided doses q8h Extended-Spectrum (Antipseudomonal) Penicillins Carbenicillin indanyl sodium PO 382–764 mg four times daily PO 30–50 mg/kg/d in divided doses q6h (Geocillin) Ticarcillin IM, IV 1–3 g q6h. IM injections should not exceed Weight < 40 kg: 100–300 mg/kg/d q6–8h (Ticar) 2 g/injection. Mezlocillin IM, IV 200–300 mg/kg/d in four to six divided Age 1 mo–12 y: 150–300 mg/kg/d in six divided (Mezlin) doses. Usual adult dosage, 3 g q4h or 4 g q6h doses, q4h Piperacillin IV, IM 200–300 mg/kg/d in divided doses q4–6h. Age < 12 y: Dosage not established (Pipracil) Usual adult dosage, 3–4 g q4–6h; maximal daily dose, 24 g Penicillin/Beta-Lactamase Inhibitor Combinations Ampicillin/sulbactam IM, IV 1. Can also be given parenterally PO 250 mg q12h; severe infec- >12 y, same as adults; (Ceftin) 2. Available only in tablet form tions, 500 mg q12h; urinary <12 y, 125 mg q12h 3. The tablet may be crushed and tract infection, 125 mg q12h Otitis media, >2 y, 250 mg q12h, added to a food (eg, applesauce), <2 y, 125 mg q12h but the crushed tablet leaves a strong, bitter, persistent aftertaste. Loracarbef A synthetic drug similar to cefaclor PO 200–400 mg q12h PO 15–30 mg/kg/d in divided (Lorabid) doses q12h Third Generation Cefdinir Indicated for bronchitis, pharyngitis, PO 300 mg q12h or 600 mg ≥13 y: PO Same as adults (Omnicef) and otitis media caused by strep- q24h for 10 d 6 mo–12 y: PO 7 mg/kg q12h tococci or H. Indicated for bronchitis, otitis media, PO 400 mg daily for 10 d Oral suspension with 90 mg/5 mL (Cedax) pharyngitis, or tonsillitis caused by Renal impairment: 10 kg: 5 mL daily streptococci or H. Available in a capsule for oral use CrCl 5–29 mL/min, 100 mg q24h Above 45 kg: Same as adults and an oral pediatric suspension Oral suspension with that comes in two concentrations 180 mg/ 5 mL (90 mg/5 mL and 180 mg/5 mL). Antimicrobial spectrum similar to IV, IM 1 g daily (q24h) (Monocid) other second-generation Surgical prophylaxis, IV, IM 1 g cephalosporins 1 h before procedure 2. Effective against most organisms IV, IM 1–2 g q12h for 5–10 d; (Cefotan) except Pseudomonas maximum dose, 3 g q12h in 2. Highly resistant to beta-lactamase life-threatening infections enzymes Perioperative prophylaxis, IV 1–2 g 30–60 min before surgery Cefoxitin 1. The ﬁrst cephamycin (derived from a IV 1–2 g q4–6h IV 80–160 mg/kg/d in divided (Mefoxin) different fungus than Surgical prophylaxis, IV 1 or 2 g doses q4–6h. Penetrates cerebrospinal ﬂuid in 30–60 min before initial skin Bacterial meningitis, IV 200– presence of inﬂamed meninges incision 240 mg/kg/d in divided doses q6–8h, reduced to 100 mg/kg/d on clinical improvement Third Generation Cefoperazone 1. Active against gram-negative and IV, IM 2–4 g/d in divided doses Dosage not established (Cefobid) gram-positive organisms, including q8–12h gram-negative organisms resistant to earlier cephalosporins 2. Excreted primarily in bile; half-life prolonged in hepatic failure Cefotaxime 1. Antibacterial activity against most IV, IM 1 g q6–8h; maximum Weight > 50 kg: same as adults (Claforan) gram-positive and gram-negative dose, 12 g/24h Weight < 50 kg and age > 1 mo: IV, bacteria, including several strains IM 50–180 mg/kg/d, in divided resistant to other antibiotics. Recommended for serious Neonates: ≤ 1 wk, IV 50 mg/kg infections caused by susceptible q12h; 1–4 wk, IV 50 mg/kg q8h microorganisms CHAPTER 34 BETA-LACTAM ANTIBACTERIALS: PENICILLINS, CEPHALOSPORINS, AND OTHERS 515 Drugs at a Glance: Parenteral Cephalosporins (continued) Routes and Dosage Ranges Generic/Trade Name Characteristics Adults Children Ceftazidime 1. Active against gram-positive and IV, IM 1 g q8–12h 1 mo to 12 y: IV 30–50 mg/kg (Fortaz) gram-negative organisms q8h, not to exceed 6 g/d 2. Especially effective against gram- <1 mo: IV 30 mg/kg q12h negative organisms, including P. Indicated for serious infections caused by susceptible organisms Ceftizoxime 1.
It must purchase 5 mg provera amex menstrual bleeding for a month, however order provera 5 mg otc women's health bladder problems, be stressed that in the elderly buckle, thus further decreasing canal space at the disc central and lateral lesions very often both participate in level. Furthermore, fibrotic chondrometaplasic changes the stenostic pathology (Fig. This reduces the elasticity of the ligamentum, which may then bulge in the canal even if it Lateral or root canal stenosis keeps a normal thickness. Several studies have shown a higher frequency of calcification of ligamentum flavum Lateral stenosis is defined as an entity in which a nerve in stenotic than nonstenotic subjects. The extent of root, dorsal root ganglion, or spinal nerve is entrapped in these histological changes appears to be correlated with its pathway. The displacement due to facet hypertro- phy can critically narrow the canal. In contrast to isthmic spondylolisthesis, degenerative spondylolisthesis is self- contained and rarely reaches grade II. Claudication, or much more often sciatic pain, are the encountered symptoms in stenosis secondary to degenerative spondylolisthesis. This is related to the fact that degenerative spondylolisthesis is usually at one level, and the two level pathogenesis de- Fig. Central stenosis is rare in entrapment lytic spondylolisthesis but in some cases of L5–S1 displace- ment the posterior element can be pulled forward against root can be subject to compression secondary to the disc the body of S1, thus compressing the corda. More of- collapse by approximation of the pedicles due to the de- ten the loss of height of the disc induces a posterior bulging, crease in disc height. Furthermore, hypertrophy of the which can trap the nerve root ion the foramen resulting in facet joint or other osteophytic changes can compress the lateral stenosis. The osteofibrous callus present at the isth- root at its entrance in the foramen or in the foramen itself mic fracture level can exceptionally become hypertrophic (Fig. Al- phytes at the insertion level of Sharpey fibers) are the rule though those conditions are usually discovered in younger in spondylosis, they seldom occur posteriorly. Other osteophytes can be found such as those resulting from the calcification of an Other conditions arthrosynovial cyst (Fig. It appears that degenerative lesions are also often present in the middle zone or exit Other conditions in the elderly can cause spinal stenosis. The vast majority of patients suffering of spinal Paget have no symptoms, of instrumentation (or even abuse of it) may cause stenotic yet when symptomatic, it is not necessarily at the level of situations. The increased vascularity of the Pagetic vertebrae may di- minish the spinal cord or the nerve root blood supply, ul- Relationship of stenosis and heavy manual work timately leading to a spinal artery steal syndrome. The Pagetic process can involve the neural arches further re- The relationship in elderly persons between back troubles ducing the diameter of the central or lateral canal. Some Some cases of amyloidosis, associated with prolonged authors have suggested a relationship between long-term hemodialysis or amyloid tumors, and causing spinal steno- heavy manual work and spinal stenosis. Using ultra- sis or even cauda equina syndrome have been reported sound measurements McDonald et al. However, amyloid deposit in the ligamentum flavum narrower spinal canal is associated with increased back- have been reported in series of patients with spinal stenosis related complaints in coal miners. There are conflicting who did not present the amyloidosis conditions described reports about the relationship of long-term heavy physical higher. The presence and the abundance of those deposits labor and/or exposure to vibration and the appearance of are closely correlated to age. The meaning of these de- spinal degeneration (disc degeneration and osteophytes). Rare In very complete review Videman and Battié found cases of epidural gas leaks originating from the degenerative only a modest relation of occupational risk factors and spi- intradiscal space may cause compressive phenomena. Iatrogenic stenosis Conclusion Iatrogenic stenoses are of course not specific to the elderly. Lumbar spinal stenosis is a very common condition in the They can happen after spinal surgery at any age (Fig. In most cases it is due to degenerative changes, However, some spinal disorders specific to the elderly are the changes can lead to symptoms by themselves or de- often treated in very aggressive way, and the generous use compensate a preexisting narrow canal. However, it must 93 be stressed that so-called stenotic images (sometimes se- of the neural pathways and differential diagnosis with vas- vere) are present on imaging studies in a great number of cular troubles, also common in the elderly, can be chal- symptom-free individuals, and that the relationship be- lenging.
Drugs that increase effects of calcium: (1) Vitamin D Increases intestinal absorption of calcium from both dietary and supplemental drug sources (2) Thiazide diuretics Reduce calcium losses in urine b cheap 2.5 mg provera mastercard menopause systems. Drugs that decrease effects of calcium: Corticosteroids These drugs lower serum calcium levels by various mechanisms generic 2.5mg provera with mastercard women's health clinic victoria hospital winnipeg. Drugs that increase effects of vitamin D: Thiazide diuretics Thiazide diuretics administered to hypoparathyroid clients may cause hypercalcemia (potentiate vitamin D effects) d. Drugs that decrease effects of vitamin D: (1) Phenytoin Accelerates metabolism of vitamin D in the liver and may cause vitamin D deﬁciency, hypocalcemia, and rickets or osteomalacia. Drugs that decrease effects of alendronate and other oral These drugs interfere with absorption of bisphosphonates and bisphosphonates: Antacids and calcium supplements should be taken at least 2 h after a bisphosphonate. Drugs that alter effects of calcitonin: (1) Testosterone and other androgens increase effects. Androgens and calcitonin have additive effects on calcium reten- tion and inhibition of bone resorption (movement of calcium from bone to serum). Drugs that decrease effects of phosphate salts: Antacids Aluminum and magnesium may combine with phosphate and containing aluminum and magnesium thereby prevent its absorption and therapeutic effect. What are some nursing interventions to prevent hypocal- Nursing Notes: Apply Your Knowledge cemia? Why is it important to have an adequate intake of calcium temple, observing for twitching, which indicates hypocalcemia. What are the main elements of prevention and treatment of the lower arm and hand. Report hypocalcemia or signs of tetany to the physician so SELECTED REFERENCES that calcium replacement can be promptly administered. Clinical effects of raloxifene Answer: It is very important to administer Fosamax with the patient hydrochloride in women. Philadelphia: Lippincott Williams & Fosomax with only a sip of water while she was in bed (probably Wilkins. Philadelphia: Lippincott Williams & through the esophagus into the stomach. Pathophysiology: Concepts of altered health with a full glass of water and have the patient remain sitting or states, 6th ed. Diagnosis and management of osteoporosis in older can increase the chance of gastric reﬂux. Assist clients or caregivers in learning how of characteristics and uses. Discuss the relationships among diet, exer- tration of antidiabetic medications. Differentiate types of oral antidiabetic agents dietitians, and others in teaching self-care in terms of mechanisms of action, indications activities to clients with diabetes. Explain the benefits of maintaining glycemic prescribed management strategies. Critical Thinking Scenario You are assigned to care for Ellen Rodriguez, a 13-year-old, who was admitted to the intensive care unit 12 hours ago in acute ketoacidosis. She lives with her mother (a single parent) and ﬁve younger siblings in public housing within the Latino commu- nity. Her mother asks why Ellen has to take shots, because her aunt did just ﬁne on pills. Ellen will be discharged in 2 to 3 days on insulin, glucose monitoring before meals and at bedtime, and a diabetic diet. Before discharge, you have three teaching sessions of approximately 30 minutes each. Prioritize essential teaching and describe your teaching plan for Ellen. Discuss appropriate postdischarge follow-up to continue diabetic teaching and monitor compliance with prescribed management strategies. OVERVIEW ENDOGENOUS INSULIN Insulin and oral agents are the two types of drugs used Insulin is a protein hormone secreted by beta cells in the pan- to lower blood glucose in diabetes mellitus. The average adult pancreas secretes 40 to 60 units of ers in understanding the clinical use of these drugs, char- insulin daily. This includes a basal amount of 1 to 2 units/hour acteristics of endogenous insulin, diabetes, and the drugs and additional amounts (4 to 6 units/hour) after meals or when are described.
Processes of Short-Term Memory Localized by Functional Imaging Cognitive Process Cortical Regions Activated VERBAL SHORT-TERM MEMORY Phonological buffer storage Left ventral parietal Rehearsal/inner speech scratchpad Left ventral posterolateral frontal VISUOSPATIAL SHORT-TERM MEMORY Visuospatial buffer Right ventral parietal Visuospatial sketchpad Right prefrontal discount provera 2.5mg overnight delivery womens health haven fayetteville nc, parietal purchase provera 5 mg on-line women's health clinic riverside hospital, dorsolateral occipital Plasticity in Sensorimotor and Cognitive Networks 59 ing studies show that spatial, visuospatial, and and cingulate cortices. The anterior cingulate verbal working memory tasks produce an (BA 24 and 32) is often activated in functional overlapping and distributed pattern of activa- imaging studies along with the DLPFC. It signals when control can handle a limited number of channels of re- needs to be more strongly engaged. The posterior cingu- Executive processes, which often operate on late in BA 23, 30, and 31 also participates in the contents of short-term working memory, memory and visuospatial processing. These ar- are also managed in the frontal lobes, prima- eas are highly connected to both the parahip- rily in prefrontal cortex. Executive cognition pocampal and DLPFC regions and may serve (1) focuses attention on relevant information as a link between them. The cingulate region and inhibits irrelevant stimuli; (2) manages also provides an emotional and motivational in- tasks, which may require switching or dividing fluence on memory. Normal pre- one or more attributes, such as spatial location, frontal cortex and its connections create much color, and the sensory stimuli associated with of what is most human, from an imaginative a motor act. Different cells, to differing degrees, were activated by a sensory input, sustained a Working Memory low level of activity in working memory for the The anatomical area involved in working mem- association, and were reactivated before and ory has been described in both macaque and during presentation of a reminder cue. The dorsolateral portion of memories of specific episodes, whereas the pre- DLPFC receives large projections from the frontal cortex represents not specific episodes, dorsal posterior parietal region to support but the rules for using sensory inputs and de- working memory for spatial tasks. The ven- cortex in BA 12/47 and 45 exert executive con- trolateral aspect of the DLPFC receives a large trol over the storehouses of cortical memory projection from the inferotemporal cortex for representations. The region FUNCTIONAL IMAGING may also bias brain systems toward a common task, controlling the selection of particular sen- Research on working memory, as well as all sory inputs, memories, or motor outputs. Data from functional imaging and frontal cortex flexibly selects cortically stored TMS studies continue to create and partially information of many sorts to construct associ- settle controversies about how specific regions ations and choose actions that are appropriate process mneumonic and executive functions. These patients act as if they cannot find mid-dorsolateral and mid-ventrolateral pre- the mental rules to guide their behavior. The frontal regions play different roles, regardless prefrontal cortex may be the only brain region of whether the task involves spatial, visual, or that can represent cues for behaviors, reper- verbal working memory. For example, among the prefrontal neurons that process in- right mid-ventral BA 47 was activated prima- formation that achieves a goal. The reward-re- rily when subjects held five verbally given num- lated signals, most likely provided by dopamine bers in mind and were asked to repeat them. As A more dorsal activation also occurs in BA 46 noted earlier, they initially fire in response to and 9 when the task requires a person to mon- unpredicted rewards. With experience, these itor or manipulate, for example, a set of spatial dopaminergic neurons are activated by cues locations held in working memory and make that predict rewards and not by the rewards comparisons with new stimuli. Their firing is inhibited when a re- memory task activates BA 9 and 46/9 on the ward does not occur. Activation studies also sugggest that pre- prefrontal neurons more rapidly over the time frontal cortex is organized by fairly separable of learning, which may help link more infor- storage and executive processes. Later, for example, especially activate the anterior with additional training, the cues that fired the cingulate. The primarily involved in the maintenance and mon- dopamine influx, then, allows for experience- itoring of items in working memory or in main- dependent plasticity. The prefrontal syndrome includes deficits more posterior and medial to those identified in motor programming, especially evident during maintenance. BA 46 may participate in alternating, reciprocal, and sequential more in the attentional than the mnemonic motor tasks. Executive function impair- component of a complex working memory ments include the inability to generate task. Patients ory and when they self-select between move- also exhibit poor organizational strategies ments on tasks that require a willed action. Lesions span the circuit that require working memory and executive from BA 9 and 10 to the dorsolateral cau- processing may help clinicians determine the date nucleus, to the globus pallidus, and readiness, capacity, and best strategies for cog- to the ventral anterior and dorsomedian nitive remediation in patients. This cir- keep the types of definable processes sub- cuit is shown to be hypometabolic in Fig- sumed under working memory and executive ure 3–3 after an anterior thalamic stroke. The range of character- Emotional Regulatory Network istics include a change in interests, initia- tive, and conscientiousness, as well as Prefrontal and orbitofrontal cortex often bear disinhibition, tactless words, irritability, the brunt of damage in traumatic brain injuries.
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