Pharm Exam #1 - Adrenergic drugs, cholinergic drugs, Cholinergic-blocking drugs, Diuretic drugs, PDF

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Adrenergic drugs, cholinergic drugs, Cholinergic-blocking drugs, Diuretic drugs, Antihypertensive drugs...

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Exam #1

Adrenergic Drugs (Sympathetic Nervous System) The neurotransmitters involved in adrenergic drugs are catecholamine’s (norepinephrine, epinephrine, and dopamine). There are receptor sites for the catecholamine’s norepi and epi throughout the body and are referred to as adrenergic receptors. Adrenergic receptors 

Alpha-adrenergic o Alpha1  Located on postsynaptic effector cells (cell, muscle, or organ that nerve stimulates) o Alpha2  Located on presynaptic nerve terminals (nerve that stimulates the effector cells)  Controls the release of neurotransmitters o Alpha-Adrenergic Agonist  Vasoconstriction  CNS Stimulation

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Beta-adrenergic are all located on postsynaptic effector cells o Beta1  Located primarily in the heart o Beta2  Located in the smooth muscle of bronchioles, arterioles, and visceral organs o Beta-Adrenergic Agonist  Bronchial, gastrointestinal, and uterine smooth muscle relaxation  Glycogenolysis  Cardiac stimulation

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Dopaminergic o Causes dilation of the following blood vessels resulting in increased blood flow

Mechanism of action 

Direct-Acting o Binds directly to the receptor and causes a physiologic response

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Indirect-Acting o Causes release of catecholamine from storage sites in nerve endings o Catecholamine binds to receptors and causes a physiologic response

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Mixed-Acting o Directly stimulates the receptor by binding to it and indirectly stimulates the receptor by causing the release of stored catecholamine’s from the nerve endings

Stimulation of alpha-adrenergic receptors on smooth muscles results in:  Vasoconstriction of blood vessels  Relaxation of GI smooth muscles (decreases motility)  Constriction of balder sphincter  Contraction of uterus  Male ejaculation  Contraction of pupillary muscles of eye (dilated pupils) Stimulation of beta1-adrenergic receptors on the myocardium, AV node, and SA node results in cardiac stimulation  Increased force of contraction (positive inotropic effect)  Increased heart rate (positive chronotropic effect)  Increased conduction through the AV node (positive dromotropic effect) Stimulation of beta2-adrenergic receptors on the airways results in  Bronchodilation (relaxation of the bronchi)  Uterine relaxation  Glycogenolysis the liver  Increased renin secretion in the kidneys  Relaxation of GI smooth muscles (decreased motility) Indications Respiratory Indications  Beta2-adrenergic receptors and cause bronchodilation. Beta2 agonists are helpful in treating conditions such as asthma and bronchitis. Indications of Topical Nasal Decongestants  Treatment for nasal congestion, stimulate alpha1-adrenergic receptors and have little or no effect on beta-adrenergic receptors Ophthalmic Indications  Stimulate alpha-adrenergic receptors located on small arterioles in the eye and temporarily relieve conjunctival congestion by causing arteriolar vasoconstriction.  Temporary relief of conjunctival congestion  Reduction of intraocular pressure and dilation of pupils

Cardiovascular Indications  Used to support the heart during cardiac failure or shock

Contraindications  

Drug allergy Severe hypertension

Adverse Effects 

Alpha-Adrenergic o CNS  Headache, restlessness, excitement, insomnia, euphoria o Cardiovascular  Palpitations, tachycardia, hypertension o Other  Loss of appetite, dry mouth, N/V

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Beta-Adrenergic o CNS  Mild tremors, headache, nervousness, dizziness o Cardiovascular  Elevated heart rate, palpitations, fluctuations in blood pressure o Other  Sweating, N/V/, muscle cramps

Toxic Effects Seizures, hypotension, hypertension, dysrhythmias, palpitations, nervousness, dizziness, fatigue, malaise, insomnia, headache, tremor, dry mouth, nausea I nt e r a c t i o ns  Ad r e n e r g i ca n t a g o n i s t( c o mpe t ea n dl i mi tt h e r a p e u t i ce ffe c t )  An e s t h e t i c s( i n c r e a s e sr i s kf o rc a r d i a cd y s r h y t hmi a s )  MAOI( ma yc a u s eh y p e r t e ns i v ec r i s i sb / ci n c r e a s el e v e l so fn o r e pia n dd o p a mi n e )  An t i hi s t a mi n e sa n dt h y r o i dp r e p a r a t i o nsi n c r e a s ee ffe c t so fa d r e ne r g i cd r u g s La bi nt e r a c t i o ns  ↑c o r t i c o t r o p h i nl e v e l s  ↑c o r t i c o s t e r o i d s  ↑g l u c o s e Dobutamine (Beta1-selectve vasoactive adrenergic drug)

Dobutamine is a beta1-selective vasoactive adrenergic drug and through stimulation of the beta1 receptors on heart muscle, it increases cardiac output by increasing contractility (positive inotropy), which increases the stroke volume, especially in patients with heart failure.

Dopamine Dopamine is a naturally occurring catecholamine neurotransmitter. It is a potent dopaminergic, as well as beta1 and alpha1 adrenergic receptor activity.    

In low dosages, dopamine acts as a dopaminergic to increase blood flow so it can dilate blood vessels in the brain, heart, kidneys, and mesentery, which increases blood flow to these areas. It is used for shock and cardiopulmonary arrest. Higher infusion rates, it works as a beta1-adrenergic to improve cardiac contractility and output Highest doses, it works as an alpha1-adrenergic causing vasoconstriction It is contraindicated in patients who have pheochromocytoma

Epinephrine    

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Acts on alpha and beta receptors It is available in 1mg/1mL (1:1000) and 0.1mg/mL (1:10000) Increases sugar levels In low doses only stimulates beta receptors o Beta1 increases force of contraction and heart rate o Beta2 bronchodilation (Asthma, anaphylaxis) In high doses stimulates alpha1 receptors o Causes vasoconstriction to elevate BP o Cardiac arrest

Norepinephrine

Norepinephrine acts predominantly by directly stimulating alpha-adrenergic receptors, which leads to vasoconstriction. It also has some direct-stimulation beta-adrenergic effects on the heart (beta1-adrenergic receptors) but none on the lung. Norepinephrine is directly metabolized to dopamine and is used primarily in the treatment of hypotension and shock. Norepi is administered by continuous infusion. Phenylephrine Phenylephrine works almost exclusive on the alpha-adrenergic. It is used primarily for short-term treatment to raise blood pressure in patients in shock. It is also used for control of supraventricular tachycardia’s, vasoconstriction in regional anesthesia, topical ophthalmic drug, and nasal decongestant. Nursing Process: Implementation    

Use of epinephrine and other alpha-adrenergic may not be indicated for shock-related symptoms because these drugs lead to vasoconstriction of the renal vessels and subsequent renal damage or shutdown Dopamine is drug of choice for shock Check site of IV for infiltration that can lead to necrosis Phentolamine is often used for the treatment of infiltration

Ch. 20 - Cholinergic Drugs (Parasympathetic) Cholinergic drugs mimic the effects of acetylcholine. These drugs can stimulate cholinergic receptors either directly or indirectly.  

Direct-acting cholinergic agonists bind directly to cholinergic receptors and activate them Indirect-acting cholinergic agonists stimulate the postsynaptic release of acetylcholine at the receptor site. Indirect-acting cholinergic drugs work by inhibiting the action of acetylcholinesterase, the enzyme responsible for breaking down acetylcholine. o Reversible inhibitors – Bind to cholinesterase for a short period of time o Irreversible inhibitors – Have a long duration of activity, and the body must generate new cholinesterase enzymes to override the effects of the irreversible drugs

Mechanism of action and Drug Effects   

Cholinergic drugs are used primarily for their effects on the gastrointestinal tract, bladder, and the eye. These drugs stimulate the intestine and bladder, which results in increased gastric secretions, gastrointestinal motility, and urinary frequency. They also stimulate constriction of the pupil, termed miosis to reduce ocular pressure.

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Increased salivation and sweating. Cardiovascular effects include decreased heart rate and vasodilation. Pulmonary effects including causing the bronchi of the lungs to constrict and the airways to narrow.

Indications 

Direct-Acting Agents o Reduce intraocular pressure o Useful for glaucoma and intraocular surgery o Topical application due to poor oral absorption; however, bethanechol is the only one administered orally. Betanechol affects the detrusor muscle of the urinary bladder and also the smooth muscle of the GI tract. It relaxes sphincters in bladder and GI tract, allowing them to empty. It is helpful for postsurgical atony (atony is a paralyzed bladder) of the bladder.

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Indirect-Acting Agents o Work by increasing acetylcholine concentrations at the receptor sites, which leads to stimulation of the effector cells. o Cause skeletal muscle contraction and are used for the diagnosis and treatment of myasthenia gravis. o Used to reverse neuromuscular blocking agents o Used to reverse anticholinergic poisoning (Example is: Physostigimine, pyridostigmine) o Indirect-Acting Agents are used to treat Alzheimer’s disease, which is a neurologic disorder in which patients have decreased levels of acetylcholine.  Cholinergic drugs increase concentrations of acetylcholine in the brain by inhibiting cholinesterase (cholinesterase breaks down acetylcholine)  There are three cholinesterase inhibitors:  Donepezil (Aricept)  Galatamine (Razadyne)  Rivastigmine (Exelon)

Contraindications        

Known drug allergy GI tract obstruction Bradycardia Defects in cardiac impulse conduction Hyperthyroidism Epilepsy Hypotension COPD

Adverse Effects

The primary adverse effects of cholinergic drugs are the consequence of overstimulation of the parasympathetic nervous system. The effects on the cardiovascular system are complex and include syncope, hypotension with reflex tachycardia, hypertension, or bradycardia, depending on if the muscarinic or nicotinic receptors are stimulated.     

Cardiovascular o Bradycardia, hypotension, conduction abnormalities CNS o Headache, dizziness, convulsions Gastrointestinal o Abdominal cramps, increased secretions, nausea, vomiting Respiratory o Increased bronchial secretions, bronchospasms Lacrimation, sweating, salivation Cholinergic crisis is the most severe consequence of an overdose of a cholinergic drug. Symptoms include circulatory collapse, hypotension, bloody diarrhea, shock, and cardiac arrest. Early signs include abdominal cramps, salivation, flushing of the skin, nausea, and vomiting. A cholinergic crisis can be reversed promptly with the administration of atropine, a cholinergic antagonist. SLUDGE, Salivation, Lacrimation, Urinary incontinence, Diarrhea/digestion, Gastrointestinal motility

Interactions Anticholinergics, antihistamines, and sympathomimetic may antagonize cholinergic drugs and lead to reduce absorption. Safety: Herbal Treatment – Gingko Biloba Gingko Biloba is commonly used to prevent memory loss, vertigo, and tinnitus. It may cause GI upset, headache, and bleeding. Potential interactions include aspirin, NSAIDs, anticoagulants, and anticonvulsants. Bethanecol Bethanecol is a direct-acting cholinergic agonist.  

It is used in the treatment of acute postoperative and postpartum non-obstructive urinary retention and for the management of urinary retention associated with neurogenic atony of the bladder. Contraindications include known drug allergy, hyperthyroidism, PUD, epilepsy and Parkinson’s.

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Interacts with acetylcholinesterase inhibitors, which can enhance the adverse effects of bethanecol. Adverse effects include syncope, hypotension with reflex tachycardia, headache, seizure, GI upset, and asthmatic attacks.

Donepezil (Aricept) Aricept is a cholinesterase inhibitor drug that works centrally in the brain to increase levels of acetylcholine by inhibiting acetylcholinesterase. Contraindications include known drug allergy. Adverse effects are GI upset, drowsiness, dizziness, insomnia, and muscle cramps. Nursing Process: Assessment         

Assess for allergies, presence of GI or GU obstructions, asthma, peptic ulcer disease, or coronary artery disease. Perform baseline assessment of VS and systems overview with special attention to baseline blood pressure readings because of the potential for orthostatic hypotension. Medications should be taken as ordered and not stopped abruptly because of the possibility of a rapid decline in cognition. The doses should be spread evenly apart to optimize the effects of the medications. Overdosing can cause life-threatening problems patients should not adjust dosages unless directed by the physician. Encourage patients with myasthenia gravis to take medication 30 minutes before eating to help improve chewing and swallowing. Atropine must be readily available to a cholinergic overdose as this medication is an antidote When donepezil (Aricept) is prescribed for Alzheimer’s disease, be honest with caregivers and patients that the drug is for management of symptoms, and not a cure. Therapeutic effects may not occur for up to 6 weeks. Patients should notify their physician if they experience muscle weakness, abdominal cramps, diarrhea, or difficulty breathing due to cholinergic crisis.

Monitory for Therapeutic Effects   

Alleviated signs and symptoms of myasthenia gravis which includes the absence of ptosis and diplopia, less difficulty swallowing and chewing, and an improvement in muscle weakness. Increase bowel sounds, passing gas, and bowel movements in postoperative patients with decreased GI peristalsis In patients with urinary retention/hypotonic bladder, urination should occur within 60 minutes of betanechol administration.

Ch. 21 – Cholinergic-Blocking Drugs Cholinergic blockers refer to the class of drugs that block or inhibit the actions of acetylcholine in the parasympathetic nervous system. 

Mechanism of action o Competitive agonists, they compete with acetylcholine for binding at the muscarinic receptors of the parasympathetic nervous system. Once they have bound to the receptor, they inhibit cholinergic nerve transmission. Thus, acetylcholine is unable to bind to the receptor site and cause a cholinergic effect. o Major sites of action of anticholinergics are the heart, respiratory tract, gastrointestinal (GI) tract, urinary bladder, eye, and exocrine glands o Have opposite effects of cholinergic (parasympathetic)  Cardiovascular system – Increase in heart rate  Respiratory system – Dry mucous membranes and bronchial dilation  GI tract – Decrease in GI motility, GI secretions, and salivation  Decreased bladder contraction, which can result in urinary retention  Leads to increased intraocular pressure because of dilation of the pupil and paralysis of the ocular lens, detrimental for glaucoma patients.

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Indications o Central Nervous System  Decreased muscle rigidity and muscle tremors, which is beneficial in the treatment of Parkinson’s disease and drug-induced extrapyramidal reactions such as those associated with antipsychotic drugs

Ch. 28 - Diuretic Drugs Diuretics are drugs that accelerate the rate of urine formation, which results in the removal of sodium and water. It is used in the treatment of hypertension, heart failure, and renal failure. Diuretics reduce extracellular fluid volume, plasma volume, and cardiac output, which may account for the decrease in blood pressure. Carbonic Anhydrase Inhibitors (CAIs) 

Mechanism of Action o Carbonic Anhydrase helps to make hydrogen ions available for exchange with sodium and water in the proximal tubules o CAIs block the action of carbonic anhydrase  This prevents the exchange of hydrogen ions with sodium and water

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Reduces hydrogen ion concentration in renal tubules  This results in increased excretion of bicarbonate, sodium, water and potassium and therefore the reabsorption of water is decreased and urine volume is increased

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Indications o Long-term management of open-angle glaucoma o Edema o High-altitude sickness o Acetazolamide (Diamox) is used in the management of edema secondary heart failure when other diuretics are not effective o CAIs are less potent diuretics when compared to loop diuretics or thiazides. Because of the metabolic acidosis they induce, it reduces their diuretic effect in 2 to 4 days

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Contraindications o Hyponatremia o Hypokalemia o Severe renal or hepatic dysfunction o Adrenal gland insufficiency o Cirrhosis

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Adverse Effects o Metabolic acidosis o Anorexia o Hematuria o Hypokalemia because of increase in aldosterone and therefore retaining losing potassium o Hyponatremia o Drowsiness o Paresthesia o Uticaria o Glycosuria and increase blood sugar in diabetic patients

Acetazolamide (Diamox) Contraindicated in patients who have shown a hypersensitivity to it as well as in those with significant liver or kidney dysfunction, low serum potassium or sodium levels, acidosis, or adrenal gland failure. Loop diuretics Loop diuretics are very potent and are chemically related to sulfonamide antibiotics. Because they are related to sulfonamides, they are often listed as contraindicated in sulfa-allergic patents;

however, literature states that they are commonly given to patients with sulfa allergy with no problems. 

Mechanism of Action o Increases renal prostaglandins which results in vasodilation and reduced peripheral vascular resistance o Acts directly on the ascending limb of the loop of Henle which inhibits chloride and sodium reabsorption o Useful when rapid diuresis is needed, because of their rapid onset of action o The diuretic effect usually lasts at least 2 hours

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Drug Effects o Potent diuresis and subsequent loss of fluid o Reduction in all of the following:  Blood pressure  Pulmonary vascular resistance  Systemic vascular resistance  Central venous pressure  Left ventricular end-diastolic pressure o Potassium and sodium depletion

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Indications o Edema associated with heart failure, hepatic, and/or renal disease o To control hypertension o To increase renal excretion of calcium in patients with hypercalemia

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Adverse Effects o Central Nervous System  Dizziness, headache, tinnitus, blurred vision, ototoxicity o Gastrointestinal  Nausea, vomiting, diarrhea o Integumentary  Stevens-Johnson syndrome o Hematologic  Agranulocytosis, neutropenia, thrombocytopenia o Metabolic  Hypokalemia, hyperglycemia, hyperuricemia

Furosemide (Lasix) and Bumetanide (Bumex) Furosemide is the most commonly used loop diuretic in clinical practice. It is used in the management of pulmonary edema and edema associated with heart failure, liver disease, nephrotoxic syndrome, and ascites. Osmotic Diuretics

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Mechanism of Action o Pulls water into the renal tubules from the surrounding tissues o Inhibits tubular reabsorption of water and solutes; therefore, producing rapid diuresis o Not indicated in patients with peripheral edema because of the slight loss of electrolytes and therefore does not promote sufficient sodium excretion o Increases GFR and renal plasma flow by inducing vasodilation. This helps to prevent kidney damage during acute renal failure o Reduces excessive intraocular pressure o Reduces intracranial pressure or cerebral edema associated with head trauma

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Indications o Early, oliguric phase of acute renal failure o Promotes excretion of toxic substances o Reduces intracranial pressure o Cerebral edema o NOT indicated for peripheral edema

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