By D. Kadok. Wilmington College, Wilmington Ohio.
SSRIs are not approved in children (<18 years of age) generic 10 mg zebeta otc, TCAs may cause or aggravate conditions that are common and their safety and effectiveness have not been estab- in older adults (eg buy generic zebeta 5 mg line, cardiac conduction abnormalities zebeta 5mg, urinary lished generic 5mg zebeta with amex. However, for children, as for other groups, retention, narrow-angle glaucoma). In addition, impaired these drugs are considered first-line antidepressants compensatory mechanisms make older adults more likely to and safer than TCAs and MAOIs. Common adverse ef- experience anticholinergic effects, confusion, hypotension, fects include sedation and activation; it is often diffi- and sedation. If a TCA is chosen for an older adult, nor- cult to distinguish therapeutic effects (improvement of triptyline or desipramine is preferred. In addition, any TCA mood, increased energy and motivation) from the ad- should be given in small doses initially and gradually in- verse effects of behavioral activation (agitation, hypo- creased over several weeks, if necessary, to achieve thera- mania, restlessness). TCAs are not recommended for use in children younger because the drugs are metabolized and excreted more slowly than 12 years of age except for short-term treatment of than in younger adults. Initial dosage should be decreased by enuresis in children older than 6 years of age. However, 30% to 50% to avoid serious adverse reactions; increments they are used to treat depression, mainly amitriptyline, should be small. Vital signs, serum drug levels, and ECGs desipramine, imipramine, and nortriptyline. When a TCA is used for enure- sis, effectiveness may decrease over time, and no resid- Use in Renal Impairment ual benefits continue once the drug is stopped. Common adverse effects include sedation, fatigue, nervousness, Antidepressants should be used cautiously in the presence of and sleep disorders. Mild or moderate impairment has first choice for adolescents because TCAs are more few effects, but severe impairment may increase plasma lev- toxic in overdose than other antidepressants and suicide els and adverse effects of virtually all antidepressants. If given to a client with renal im- zodone, and venlafaxine in children younger than pairment or unstable renal function, the dose must be markedly 18 years of age. Lithium is not approved for use in children younger than 12 years of age, but it has been used to treat bipo- lar disorder and aggressiveness. Children normally ex- Use in Hepatic Impairment crete lithium more rapidly than adults. As with adults, initial doses should be relatively low and gradually in- Hepatic impairment leads to reduced first-pass metabolism creased according to regular measurements of serum of most antidepressant drugs, with resultant higher plasma drug levels. The drugs should be used cautiously in clients with severe liver impairment. Cautious use means lower doses, longer intervals between doses, and slower dose increases Use in Older Adults than usual. Fluoxetine and sertraline are less readily metabolized to SSRIs are the drugs of choice in older adults as in younger their active metabolites with hepatic impairment. In clients ones because they produce fewer sedative, anticholinergic, with cirrhosis, for example, the average half-life of fluoxe- cardiotoxic, and psychomotor adverse effects than the TCAs tine may increase from 2 to 3 days to more than 7 days, and and related antidepressants. These drugs produce similar ad- that of norfluoxetine, the active metabolite, from 7 to 9 days verse effects in older adults as in younger adults. Clearance of sertraline is also decreased in clients their effects in older adults are not well delineated, SSRIs with cirrhosis. Paroxetine has a short half-life and no active may be eliminated more slowly, and smaller or less frequent metabolites, but increased plasma levels can occur with se- doses may be prudent. Nefazodone has been associated with a few cases of liver failure and should not be given to clients with severe liver im- Home Care pairment. In addition, blood levels of nefazodone are higher in clients with cirrhosis. Whatever the primary problem for which a home care nurse is visiting a client, he or she must be vigilant for signs and symptoms of major depression.
Ann of fluoxetine and maprotiline on functional recovery Neurol 1999; 45:430–438 purchase 5mg zebeta otc. Walker-Batson D zebeta 5mg mastercard, Smith P discount 5 mg zebeta fast delivery, Curtis S purchase zebeta 10mg with amex, Unwin H, A positron emission tomographic study. Leff A, Crinion J, Scott S, Turkheimer F, Howard Stroke 1995; 26:2254–2259. Grade C, Redford B, Chrostowski J, Toussaint L, cortex following left posterior temporal lobe infarc- Blackwell B. Potential effects of common drugs on frontal cortex induces dopamine release in the cau- stroke recovery. Positron emission tomographic imaging proves activated blood flow and facilitates rehabili- of serotonin activation effects on prefrontal cortex tation of poststroke aphasic patients. Dysfunction in tromethorphan decreases the excitability of the hu- the neural circuitry of emotion regulation-a possible man motor cortex. Pfefferbaum A, Desmond J, Galloway C, Menon V, etine and fenozolone during hand sensorimotor tasks. Reorganization of frontal sys- J Cereb Blood Flow Metab 1999; 19:1365–1375. Brain Mapping: hanced after a single dose of serotonin reuptake in- The Methods. Pariente J, Loubinoux I, Carel C, Albucher J, Ras- in the frontal lobes. The role of the lateral frontal cortex in formance and cerebral activation of patients recov- mnemonic processing: The contribution of functional ering from stroke. Worsley K, Liao C, Aston J, Petre V, Duncan H, Horn J, Bigelow L, Weinberger D. A general statistical analysis amine enhances neural network-specific physio- for fMRI data. Mattay V, Callicott J, Bertolino A, Heaton I, Frank NeuroImage 2000; 12:1–13. Effects of dextroamphetamine on cognitive per- substrates for the effects of rehabilitative training on formance and cortical activation. Chapter 4 Neurostimulators and Neuroprostheses PERIPHERAL NERVOUS SYSTEM DEVICES with acquired deafness. Visual prostheses that Functional Neuromuscular Stimulation stimulate visual cortex are becoming feasible. Nerve Cuffs Computational power in inexpensive com- CENTRAL NERVOUS SYSTEM DEVICES puters has grown so great that neurorobotic Neuroaugmentation and neuroprosthetic devices may eventually Spinal Cord Stimulators manage complex tasks, most likely when stim- Brain–Machine Interfaces ulation sequences and intensities come to be Sensory Prostheses guided by sensory feedback. Microelectro- Upper Extremity mechanical systems (MEMS) such as pressure Lower Extremity sensors, accelerometers, optical switches, ac- TELETHERAPY tuators, pumps, gears, and pulleys that fit on a SUMMARY grain of rice or ride a red blood cell are im- proving manufactured goods and health-care items. The MEMS and even tinier nanoelec- Along with the generation of axons and neu- tronic devices now analyze bodily fluids and rons to aid neurorecovery, the first quarter of measure skin pressure or blood pressure after the 21st century will see the creation of inter- implantation. These sensors, analyzers, and faces that allow neurons to drive or be driven motors may soon become integrated into neu- by computers and micromachines (Table 4–1). At a minimum, a cortical or subcortical neuronal assembly or they will lessen handicaps by making the envi- along a central or peripheral nerve. Neurons that form of nerves and motor points in muscle to per- a circuit with semiconductor chips2 may fur- mit grasping with a plegic hand or to empty a ther integrate MEMS devices with the nervous neurogenic bladder. Such cyborg-like modules of silicon vices have been created for quadriplegic sub- neurons could partially patch a disconnection jects. Patterns of cerebral electrical activity ex- in a cortical or spinal circuit. Brain-derived signals implanted sensors and stimulators, in online may soon command neuroprostheses.
The drugs discussed in this Adrenergic (sympathomimetic) drugs produce effects sim- chapter (epinephrine buy 5 mg zebeta visa, ephedrine buy zebeta 5 mg with visa, pseudoephedrine zebeta 5 mg without a prescription, isopro- ilar to those produced by stimulation of the sympathetic ner- terenol discount zebeta 10 mg free shipping, and phenylephrine) are those with multiple effects and vous system (see Chap. Some of the drugs are exogenous Because epinephrine, ephedrine, and pseudoephedrine stimu- formulations of naturally occurring neurotransmitters and late both alpha- and beta-adrenergic receptors, these drugs hormones such as norepinephrine (Levophed), epinephrine have widespread effects on body tissues and multiple clinical (Adrenalin), and dopamine (Intropin). Isoproterenol stimulates beta-adrenergic receptors (both ications such as phenylephrine (Neo-Synephrine), pseudo- beta1 and beta2) and may be used in the treatment of several ephedrine (Sudafed), and isoproterenol (Isuprel) are synthetic clinical conditions. Phenylephrine stimulates alpha-adrenergic chemical relatives of naturally occurring neurotransmitters receptors and is used to induce vasoconstriction in several and hormones. Major thera- ized therapeutic effects and fewer systemic adverse effects. IV injection (1:1000): Dilute 1 mg with 10 mL NaCl injection for a final concentration of 1:10,000 or 0. Single dose maximum: 1 mg (10 mL) Epinephrine 1% aqueous solution (1:100) for inhalation (nebulization): Instill 8–15 drops into nebulizer reservoir. Epinephrine by metered dose inhaler (MDI) (∼200–275 mcg/puff): 1 puff at onset of bronchospasm. Cardiac arrest Aqueous epinephrine Aqueous epinephrine 1 mg/mL (1:1000): 0. Allergic reaction/ Aqueous epinephrine 1 mg/mL (1:1000): Aqueous epinephrine 1 mg/mL: (1:1000): anaphylaxis IM, SC: 0. Hypotension IM, SC: 25–50 mg IV push: 5–25 mg/dose slowly, repeated q 5–10 min as needed then q3–4 h. Pseudoephedrine (Sudafed) Nasal congestion Give 30–60 mg PO q4–6h or 120 mg 6–12 y: PO 30 mg q6h. Glossets: 10 and 15 mg Glossets: 10 mg SL 10–20 mg q3–4h, not to exceed SL 5–10 mg tid not to exceed 30 mg/day. Cardiac dysrhythmias IV 20–60 mcg bolus initially, followed by IV infusion. Titrate to patient response: (2–10 mcg/min) Shock Dilute 1 mg/250 mL D5W, NS, or LR and infuse at 0. Table 18–1 nephrine, isoproterenol, norepinephrine, and phenylephrine lists commonly used adrenergic drugs in relation to adrenergic are examples of direct-acting adrenergic drugs. Indirect adrenergic effects may be produced by drugs such as amphetamines that increase the amount of nor- Mechanisms of Action and Effects epinephrine released into the synapse from storage sites in nerve endings (Fig. Norepinephrine then stimulates Adrenergic (sympathomimetic) drugs have three mecha- the alpha and beta receptors, producing sympathetic effects nisms of action. Inhibition of norepinephrine reuptake from the directly with postsynaptic alpha1- or beta-adrenergic recep- synapse is another mechanism that will produce indirect tors on the surface membrane of body cells (Fig. Remember that norepinephrine reuptake CHAPTER 18 ADRENERGIC DRUGS 271 TABLE 18–1 Commonly Used Adrenergic Drugs Generic/Trade Name Major Clinical Uses Adrenergic receptor Alpha and Beta Activity (alpha1, beta1, beta2) Nerve ending Dopamine (Intropin) Hypotension and shock Epinephrine (Adrenalin) Allergic reactions, cardiac arrest, NE NE hypotension and shock, local NE vasoconstriction, broncho- NE dilation, cardiac stimulation, NE ophthalmic conditions Ephedrine Bronchodilation, cardiac stimula- NE NE tion, nasal decongestion Norepinephrine Pseudoephedrine Nasal decongestion (Sudafed) NE Norepinephrine (Levophed) Hypotension and shock NE Alpha Activity Effector organ Metaraminol (Aramine) Hypotension and shock Naphazoline hydrochloride Nasal decongestion (Privine) Adrenergic drug Oxymetazoline hydrochloride Nasal decongestion (Afrin) Phenylephrine Hypotension and shock, nasal (Neo-Synephrine) decongestion, ophthalmic Figure 18–1 Mechanism of direct adrenergic drug action. Adrener- conditions gic drugs interact directly with postsynaptic alpha1 and beta receptors Propylhexedrine on target effector organs, activating the organ in a similar fashion as (Benzedrex) the neurotransmitter norepinephrine. Tetrahydrozoline hydrochloride Nasal decongestion, local (Tyzine, Visine) vasoconstriction in the eye Tuaminoheptane (Tuamine) Nasal decongestion Xylometazoline hydrochloride Nasal decongestion Because most body tissues have both alpha and beta recep- (Otrivin) tors, the effect produced by an adrenergic drug depends on the Beta Activity type of receptor activated and the number of affected receptors Albuterol (Proventil) Bronchodilation in a particular body tissue. Some drugs act on both types of re- Bitolterol (Tornalate) Bronchodilation Dobutamine (Dobutrex) Cardiac stimulation ceptors; some act more selectively on certain subtypes of re- Isoproterenol (Isuprel) Bronchodilation, cardiac stimulation ceptors. Activation of alpha1 receptors in blood vessels results Isoetharine (Bronkosol) Bronchodilation in vasoconstriction, which then raises blood pressure and de- Metaproterenol (Alupent) Bronchodilation Bronchodilation creases nasal congestion. Activation of beta1 receptors in the Pirbuterol (Maxair) Salmeterol (Serevent) Bronchodilation heart results in cardiac stimulation (increased force of myocar- Terbutaline (Brethine) Bronchodilation, preterm dial contraction and increased heart rate). Activation of beta2 labor inhibition receptors in the lungs results in bronchodilation and activation of beta2 receptors in blood vessels results in vasodilation (increased blood flow to the heart, brain, and skeletal muscles, the tissues needed to aid the fight-or-flight response). Many is the major way that sympathetic nerve transmission is ter- newer adrenergic drugs (eg, beta2 receptor agonists used as minated. Drugs such as tricyclic antidepressants and cocaine bronchodilators in asthma and other bronchoconstrictive dis- will block norepinephrine reuptake, resulting in stimulation orders) were developed specifically to be more selective. The In addition to the cardiac, vascular, and pulmonary effects, third mechanism of adrenergic drug action is called mixed other effects of adrenergic drugs include contraction of gastro- acting and is a combination of direct and indirect receptor intestinal (GI) and urinary sphincters, lipolysis, decreased GI stimulation. Ephedrine and pseudoephedrine are examples tone, changes in renin secretion, uterine relaxation, hepatic of mixed-acting adrenergic drugs.