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109 Cards in this Set
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d-tubocurarine+
� |
. Rarely used because it causes more
cardiovascular difficulties than others and also releases more histamine 2. Too much d-tubocurarine causes skeletal muscle paralysis 3. Override its blockade by giving an AChE inhibitor 4. Is broken down if given orally- must be given by IV 5. Only used as a surgical adjunct during general anesthesia 6. Duration of action: 60-80 min � |
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Pancuronium+
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1. Fairly long-acting competitive blocker
2. Doesn't release much histamine, doesn’t cause much ganglionic blockade, nor does it affect cardiovascular system much 3. Better drug to use in asmathics & in patients with cardiovascular problems � |
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Doxacuronium+
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1. long-acting competitive blocker similar to
pancuronium 2. doesn’t affect cardiovascular system much, except some cases of hypotension reported � |
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Vecuronium+
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1. Duration of action intermediate
2. No ganglionic blockade or histamine release 3. in rare cases, it can cause tachycardia- can be dangerous in hyperthyroid patients sensitized to catecholamines � |
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Atracurium+ �
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1. duration of action intermediate similar to
vecuronium 2. it shows little effect on cardiovas. syst., but can cause some histamine release -which will lead to hypotension 3. tachycardia has been reported in a few patients � |
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Rocuronium+
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1. intermediate-acting blocker similar to
vecuronium 2. doesn’t have much effect on cardiovascular syst., but a few cases of arrhythmias, abnormal ECG, tachycardia and transient hypotension (2%) and hypertension (2%) been reported � |
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Mivacurium+
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1. is a fast-acting non-depolarizing blocker
2. it shows some effect on cardiovas. system (mediated by autonomic or histamine release) 3. a few cases of hypotension, tachycardia & cardiac arrhythmias have been reported in a few patients � |
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succinylcholine+
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(Depolarizing!!)
1. An agonist, produces skeletal muscle relaxation 2. Very short duration of action- 5 min due to breakdown by pseudocholinesterase in the plasma 3. Mainly used for short-term procedures such as endotracheal intubation & to protect skeletal muscle during electroshock therapy 4. Releases histamine so will reduce blood pressure � 5. Causes bradycardia by stimulating vagus 6. Elevates plasma K+ levels(don't give to pts taking digitalis because it competes for calcium) 7. Can cause prolonged apnea (or respiratory arrest) in patients with atypical pseudocholinesterase (can not hydrolyze succinylcholine as effectively) 8. No drug antidote for succinylcholine overdose 9. More prone to cause malignant hyperthermia than other skeletal muscle relaxants also raises intraocular pressure so don't give to narrow angle glaucoma pts � |
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Drug Interactions(muscle relaxants)
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Certain general anesthetics stabilize
postjunctional membrane (i.e., halothane and isoflurane) & make depolarization at nicotinic receptor more difficult. Therefore, dose of a d-tubocurarine-like competitive neuromuscular blocker should be reduced when using one of these anesthetics �Aminoglycoside antibiotics (i.e., neomycin, kanamycin) and tetracycline reduce prejunctional release of ACh by chelating Ca2+. Less ACh arrives at nicotinic receptor for d-tubocurarine-like drug to block. Reduce dose of competitive blocker if used as a surgical adjunct in a patient taking one of these antibiotics. � |
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what to give with muscle relaxant overdose leading to respiratory paralysis?
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Neostigmine(preferable to physostigmine b/c it doesn't cross BBB)
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Contraindications of Neuromuscular Blockers
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Asthma-d-tubocurarine, mivacurium,
and succinylcholine b. Narrow-angle glaucoma - succinylcholine c. Hyperthyroid condition - vecuronium � |
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Dantrolene
� |
Reduces intracellular Ca2+ conc.
postjunctionally in skeletal muscle by reducing Ca2+ release from sarcoplasmic reticulum through binding and blocking ryanodine receptor channel. This inhibition causes downstream effect of muscle relaxation. b. Used to provide muscle relaxation in patients with stroke, multiple sclerosis, or malignant hyperthermia, but dantrolene causes overall muscle weakness �Malignant hyperthermia can often occur in surgical patients who are given certain general anesthetics (e.g., halothane) in conjunction with succinylcholine 1. An explosive release of Ca2+ causes exaggerated skeletal muscle contraction - also, body temp is elevated to dangerously high levels 2.Dantrolene helpful because it reduces Ca2+ release & prevents explosive muscle contraction 3. Dantrolene does not interfere with prejunctional release of ACh � |
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Cyclobenzaprine (Flexeril)
� |
Useful for muscle spasm. Has advantage
over Valium- it does not produce as much dependence b. Mechanism of action unknown, but it does block the reuptake of NE c. Should not be taken simultaneously with an MAO inhibitor d. Side effects are similar to those for tricyclic antidepressants & scopolamine. These include dry mouth, drowsiness, tachycardia, & blurred vision � |
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Neostigmine+ �
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reversible.
Due to positive charge will not cross BBB readily & does not cause CNS effects b. Is hydrolyzed to edrophonium by AChE c. Duration of action: 2-4 hours d. Good drug for treatment of paralytic ileus or bladder atony e. Can be used for wide-and narrow-angle glaucoma f. Was the drug of choice for treatment of myasthenia gravis � |
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Guanidine�
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Used to treat lambert eaton and botulism. enhances release of Ach.
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α-bungarotoxin �
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used to differentiate MG and lambert eaton. inverse relationship of severity of disease.
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Pyridostigmine+
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reversible
a. Now considered "drug of choice" for treatment of myasthenia gravis 1. Positively charged & has a longer duration of action than neostigmine 2. Duration of action: 3-6 hours 3. Absorbed better than neostigmine 4. Fewer side effects than neostigmine (i.e., diarrhea) � |
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Edrophonium+
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reversible
a. Competitively binds to both the esteratic & anionic sites b. Very short acting (5 min) c. Not hydrolyzed by AChE d. Rapidly cleared by the kidneys e. Drug of choice for diagnosis of myasthenia gravis f. Causes an immediate improvement in muscle strength upon I.V. injection g. Can be used to treat supraventricular tachycardia**** h. Can be used to treat overdose of d-tubocurarine like drug � |
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Physostigmine
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reversible
a. Not charged so will cross BBB & cause CNS effects **** b. Mainly used in the eye in conjunction with pilocarpine for treatment of narrow angle glaucoma until iridectomy can be done*** c. Can be used as an antidote for atropine intoxication *** � |
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Tacrine (Cognex)
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a. Reversible AChE inhibitor that crosses
BBB and increases ACh levels centrally 1. First drug approved for treatment of Alzheimer's disease (Only effective in about 20% of patients) � |
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Donepezil (Aricept®) �
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a. Second drug to be approved for
treatment of Alzheimer's disease 1. In animals, this drug is reported to have a high degree of selectivity for AChE in the CNS & little peripheral activity (This report may be suspect in that central and peripheral AChE are virtually identical kinetically) 2. Exhibits less hepatotoxicity than tacrine � |
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Echothiophate+ �
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Irreversible!!
a. Positively charged & long acting b. Only used topically in the eye, mainly for wide angle glaucoma, but better drugs available � |
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Mipafox�
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Irreversible
a. An organophosphate used as an insecticide 1. causes delayed neurotoxicity 8-14 days after drug exposure 2. No drug antidote for delayed neurotoxicity � |
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Parathion
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irreversible
a. an organophosphate compound b. a potent insecticide & acaricide c. highly toxic to humans & some wild life d. does not cause delayed neurotoxicity � |
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Sarin
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irreversible
a. also an organophosphate b. chemical warfare agent (a nerve gas) c. most toxic & rapidly acting (i.e., much more potent than organophos. pesticides) d. clear odorless liquid, but evaporates quickly into vapor (gas)& spread into environment e. usually can be lethal even at very small conc.; due to suffocation (asphyxia), unless antidote quickly administered f. causes moderate level of delayed neurotoxicity � |
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Antidotes for Organophosphate Intoxication �
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a. Pralidoxime+ (2-PAM)
1. "Pulls" organophosphate off esteratic site of AChE 2. Must be given rapidly to prevent "aging" of AChE 3. Works especially well at the NMJ (drug active at muscarinic & nicotinic sites*** thats why you get muscarinic excess!! b. Obidoxime-similar to pralidoime �c. Atropine (an effective muscarinic antagonist) 1. Not charged and thus will cross the BBB Controls signs of muscarinic excess; it blocks muscarinic effects of excess salivation, miosis, bronchoconstriction, bronchiole secretions, &sweating caused by inhibition of AChE at muscarinic receptor sites. a. Only needed for approximately two weeks during treatment for myasthenia gravis because muscarinic side effects of AChE inhibitors dissipate.*** � |
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calcium gluconate
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treats lambert eaton and botulism. enhances Ach release.
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Low dose epinephrine
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Low dose
Vascular effects redistribution of blood flow (regional responses) regions rich in a1 see vasoconstriction regions rich in B2 see vasodilation no significant change in TPR Cardiac effects: direct responses Blood pressure: Increase systolic, decrease diastolic � |
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epinephrine clinical uses, adverse effects, and contraindications
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Acts on all!
Clinical Uses -Hypersensitivity -Bronchodilator -Asthma -Anaphylaxis -Vasoconstriction -Angioedema -Adjunct to local anesthetics -Cardiac stimulant -Lower intraocular pressure in wide angle glaucoma �Adverse Effects -Arrhythmias -Cerebral hemorrhage -Anxiety symptoms (somatic) Contraindication - nonselective β � |
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epinephrine High dose
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High dose
Vascular effects: looks like NE a1 predominates globally, locally there is still B2 stimulation, net effect increased TPR Cardiac effects - NE like direct effects + reflex responses Blood pressure - NE like pulse pressure -narrowing � |
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Norepinephrine
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Acts on a1,a2,B1 but not B2!!!
Endogenous Cardiovascular Effects Vascular (direct: a1 vasoconstriction) Cardiac (direct: B1 [force & HR] + reflex [HR]) Blood Pressure - increased TPR + CO Non-cardiovascular Effects - minor Clinical Uses -limited Vasoconstriction Adverse Effects -Arrhythmias -Cerebral hemorrhage � � � |
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Dopamine
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Low dose acts on D1 and causes vasodilation
High dose acts on a1 or a2 and causes vasoconstriction Clinic Uses -Increase renal blood flow -Shock -Cardiac failure -Cardiac stimulant -Cardiac failure Must give IV -Limits its usefulness in chronic cardiac failure. -Can be advantage in acute cardiac failure. Adverse Effects -Arrhythmias � Cardiovascular Effects dose dependent -Vascular -Cardiac -Blood Pressure Non-cardiovascular Effects - minimal � � |
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Oxymethazoline�
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Clinical Uses
Dristan, Afrin others: Over the counter decongestant Mechanism of Action α1 & α2 adrenergic agonist �Adverse effects continued use causes rebound congestion via down regulation of α2 receptors Contraindications - drug sensitivity � |
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Phenylephrine�
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Clinical Uses
Ophthalmological – to produce: - mydriasis Mechanism of Action - α1 agonist � Adverse effects Rebound nasal/ sinus hyperemia Contraindications - drug sensitivity � |
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Clonidine�
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a2 agonist!
Clinical Uses - mild-to-moderate hypertension - used alone or in comb. Mechanism of Action - α2 agonist �Adverse effects - drowsiness - dry mouth - GI disturbance - muscle weakness - withdrawal symp. Contraindications - drug sensitivity � |
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Isoproterenol�
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Acts on B1 and B2(agonist)
Cardiovascular Effects Vascular Effects (direct B2 vasodilation) Cardiac Effects (direct B1: force, rate + reflex) Blood Pressure - widening pulse pressure Non-cardiovascular Effects Smooth muscle Bronchial - (direct B2: bronchodilation) GI/Bladder Uterine - (direct B2: dilation in late gestation) Metabolic - less than epinephrine � |
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Dobutamine�
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B1 agonist
Clinical Uses Cardiac stimulant Cardiogenic shock Cardiac failure Must be given IV -Limits its usefulness in chronic cardiac failure. -Can be advantage in acute cardiac failure. �Adverse effects -Arrhythmias Tolerance develops with use � |
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Albuterol�
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B2 agonist!
Clinical Uses - bronchodilator - asthma - COPD Mechanism of Action - B2 agonist - relaxes bronchial smooth muscle with little effect on heart rate �Adverse effects - CV: angina - CNS stim.; - GI disturbance - muscle cramps Contraindications - drug sensitivity - tachyarrhythmias - pregnancy � |
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Fenoldopam�
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D1 agonist!!
Prototype – D1 Agonist Mechanism – Vasodilation Clinical Use – Severe hypertension Short t1/2 & not absorbed by gut (i.v. only) Adverse Effects Hypotension Tachycardia � |
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Bromocriptine�
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D2 agonist!!
Prototype – D2 Agonist (ergot derivative) Clinical Use – hyperprolactinemia - Parkinson’s Mechanism – suppress prolactin release from adenomas and shrink tumor, improve motor function Adverse Effects - CNS, CV, GI Contraindications - hypersensitivity � |
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allergic rxns
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epi, phenylephrine(w/ nasal congestion)(a1 agonist)
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ADHD or Narcolepsy
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Modafinil or methylplenidate(aphetamines)
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asthma or COPD
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albuterol(B2 agonist)
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CHF
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Dopamine, Dobutamine(B1 agonist)
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HTN
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Clonidine(a2 agonist) or if severe….. fenoldopam(D1 agonist)
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Hyperprolactinemia
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Bromocriptine(D2 agonist)
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Nasal decongestion
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Phenylephrine or oxymethazoline
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mydriasis
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phenylephrine(a1 agonist)
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shock
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Dobutamine(B1 agonist) best or dopamine
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weight reduction
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modafinil
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acute hypotension or chronic orthostatic hypotension
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phenylephrine(a1 agonist!!!)
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Tamsulosin (flomax®)(& alfuzosin)
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Uroselective” a1a Antagonist�
Clinical Use Benign Prostatic Hyperplasia (BPH) Adverse Effects -Retrograde ejaculation (less with alfuzosin) secondary to relaxation of bladder neck (sphincter) smooth muscle? NOTE: Avoids orthostatic hypotension in most � |
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Phenoxybenzamine� or phentolamine
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nonselective alpha antagonist
Clinical Uses - symptomatic management of pheochromacytoma - treatment of hypertensive crisis caused by sympathomimetic amines - micturition problems Mechanism of Action - irreversible α antagonist - ↓ vasocon. by Epi & NE� Adverse effects - ↓ blood pressure - GI - postural hypotens. - reflex CV stim. - pupil constriction - partial agon/antag. at 5HT2A Contraindications - drug sensitivity � |
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Prazocin�(and other -zocins)
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a1 antagonist
Clinical Uses - hypertension - PTSD - benign prostatic hyperplasia - scorpion stings Mechanism of Action - α1 antagonist - relaxes smooth muscle - lowers blood pressure - PDE inhibition Adverse effects - postural hypotens. - syncope Contraindications - drug sensitivity � � |
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Yohimbine�
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a2 antagonist
Clinical Uses - limited - sexual dysfunction* - diabetic neuropathy - postural hypotension Mechanism of Action - α2 antagonist - increases SNS outflow - ↑ blood pressure & HR �Adverse effects - ↑ motor activity - tremors - also antagonist of most 5HT receptors - anxiety - insomnia Contraindications - drug sensitivity � |
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Propranolol�
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B antagonist
Clinical Uses - hypertension - angina - arrhythmias / tachycardia - pheochromocytoma - prophylaxis of migrane - tremor, Parkinson, alcohol WD* Mechanism of Action - non-selective antagonist - constricts bronchial smooth muscle �Adverse effects - CV: angina - CNS - GI disturbance - others; extensive Contraindications - drug sensitivity - congestive heart failure - COPD � |
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Timolol�
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B antagonist
Clinical Uses -open-angle glaucoma: -low anesthetic properties -better tolerated than Pilocarpine -Ischemic Heart disease Mechanism of Action- B antagonist �Adverse effects - cardiac arrhythmias - bradycardia - blurred vision - GI disturbance - bronchospasms Contraindications - bronchial asthma, COPD, heart failure � |
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Carvedilol�
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a1, B antagonist
Clinical Uses - Heart failure progression: reduce sudden death rate - Post MI: reduce death rate -Hypertension: reduce bp & heart rate, plasma renin activity & renal vascular resistence . Mechanism of Action- α1,B antagonist (a racemic mixture) �Adverse effects -CV: bradycardia, hypotension -CNS: dizziness, abnormal vision -GI disturbance: diarrhea, nausea, vomiting Contraindications -bronchial asthma, AV block, severe bradycardia, severe renal impairment, drug sensitivity � |
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Atenolol�
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B1 antagonist
Clinical Uses - hypertension - elderly patients with isolated systolic HT (effective when given in comb. with diuretic) - angina - post MI treatment Mechanism of Action - B1 antagonist �Adverse effects - CV: bradycardia - CNS: - GI disturbance - impotence Contraindications - drug sensitivity - bradycardia - pregnancy � |
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Esmolol�
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B1 antagonist
Clinical Uses - supraventricular tachycardia (e.g., atrial fibrillation & atrial flutter) - reduce systolic pressure - Mechanism of Action- very short-acting 1 antagonist �Adverse effects -CV: cardiac arrest,hypotension peripheral ischemia -GI disturb: nausea, vomiting -CNS: dizziness,headache, convulsion, anxiety, depression, confusional state, agitation Contraindications - bradycardia - cardiogenic shock - pulmonary hypotension - drug sensitivity � |
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Metoprolol�
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B1 antagonist
Clinical Uses Hypertension (more effective when comb. w/ diuretic - Angina - Heart failure Mechanism of Action- B1 antagonist �Adverse effects - CV: slow heart rate, symptoms of heart failure - CNS: dizziness, drowsiness, tiredness, shortness of breath, mood swings, depression Contraindications - severe bradycardia, cardiogenic shock, drug sensitivity � |
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Betaxolol�
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B1 antagonist
Clinical Uses - chronic open angle glaucoma1 - hypertension2 Mechanism of Action - B1 antagonist �Adverse effects - ocular discomfort1 - bradycardia2 - depression2 - GI disturbance2 - bronchospasm2 Contraindications - drug sensitivity - pregnancy � |
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Butoxamine�
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B2 antagonist
nothing else… he said prob no test questions cause its new |
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Clozapine�
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D2 antagonist
Clinical Uses - refractory schizophrenia Mechanism of Action - D2 antagonist - weak action on all other DA receptors (α adrenergic, cholinergic, H1 and 5HT as well).� Adverse effects - CV: tachy., angin. - CNS; drowsy, dizzy - GI disturbance - neuromuscular Contraindications - drug sensitivity - epilepsy - CNS depression - myeloprolif. disor. � |
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5 alpha reductase inhibitors vs alpha adrenergic antagonists
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decreases mechanical obstruction(size of prostate)
decreases dynamic obstruction(relaxes muscle) |
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α-methyltyrosine �
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inhibits TH, depletes NE(interferes with making of NE)
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cocaine, TCAs
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block reuptake of NE
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amphetamines
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stimulate release and block reuptake of NE
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reserpine
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Block of vesicular transport: use – mild hypertension
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bretylium
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Prevention of release of transmitter: ER for vent. tachy, fib.
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tranylcypromine�
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Inhibition to transmitter degradation�… i.e MAO inhibitor
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angina(antagonist)
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propanolol or atenolol
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arrythmias(antagonists)
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atenolol, propanolol, and possibly bertylium
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BPH
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Tamsulosin(best), prazosin, doxazosin, terazosin
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CHF(antagonists)
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metaprolol, prazosin, carvidolol
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glaucoma
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Timolol, betaxolol
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Heart failure(antagonists)
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metaprolol
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HTN(antagonists)
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propanolol, metaprolol, atenolol, betaxolol, reserpine
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hyperthyroidism
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propanolol
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ischemic heart disease
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timidol, metaprolol, carvidelol
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pheochromocytoma
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phenoxybenzamine, phentolamine, prazosin, propanolol
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priapism(persistant erection)
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phenylephrine
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neurological diseases
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clozapine(schizophrenia) and propanolol(tremor for parkinsons)
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postural hypotension
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yohimbine
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Pirenzepine�
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a competitive antagonist at M1
receptors 1. Acts on M1 receptors in myenteric plexus and in cerebral cortex all other muscarinic agonists do not discriminate!!! � |
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Methacholine+ �
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Muscarinic agonist!!!
a. Hydrolyzed by true but not pseudocholinesterase b. Mainly a muscarinic agonist c. Used to diagnose bronchial hyperactivity & asthmatic conditions d. Also used for diagnosis of achalasia (causes induced swallowing) � |
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Carbachol+ �
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muscarinic agonist!!
a. Longer duration of action because not broken down by either true or pseudocholinesterase b. Nicotinic & muscarinic activity c. Can be used topically in the eye for wide angle (open-angle) glaucoma 1. Open angle-glaucoma-cause unknown 2. Chronic problem � |
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Bethanechol+ �
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muscarinic agonist
a. The best among the three synthetic drugs b. Not broken down by pseudo or true AChE c. Pure muscarinic agonist d. Stimulates smooth muscle of bladder and G.I. tract preferentially over heart e. Used to treat postoperative distension, gastric atony, urinary retention, reflux esophagitis f. Adverse risks: can cause gastric distress, & bronchiole constriction � |
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Pilocarpine
� |
muscarinic agonist
a. Naturally occurring muscarinic agonist which is not charged b. Longer duration of action because not broken down by true or pseudo cholinesterase c. Cholinergic drug of choice for treatment of wide angle glaucoma d. Used to treat narrow angle glaucoma until surgery can be performed-sometimes combined with physostigmine (eserine) e. Now used to treat xerostomia that follows head & neck radiation treatments 1. Xerostomia is an autoimmune disease that decreases salivary secretions f. CNS side effects, irritability & restlessness � � |
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Cevimeline �
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a relatively new drug used
to treat dry mouth associated with Sjogren's syndrome. � |
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Side Effects of Muscarinic Stimulants �
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a. Extension of their actions at muscarinic
receptor sites on smooth muscle, glands, and heart b. Urinary frequency, diarrhea, bronchiole constriction, salivation, nausea, vomiting, bradycardia, increased HCl secretion � |
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Use of cholinergic stimulants contraindicated in ?
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asthma, hyperthyroidism, & peptic ulcer
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Atropine�
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long acting & tends to cause anxiety- competitive antagonist �
a. Retinal examination- produces mydriasis & loss of accommodation b. Antidote for organophosphate intoxication c. Adjunct for myasthenia gravis to reduce muscarinic side effects due to AChE inhibition at GI tract & bladder � |
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Scopolamine�
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shorter acting and tends to cause sedation-competitive antagonist
� a. Best drug for motion sickness 1. Transderm Scop® -fewer side effects than orally administered scopolamine b. Used to treat bedwetting (enuresis)- blocks muscarinic receptors & increase bladder capacity � |
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Homatropine�
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c. Retinal examination in adults- shorter acting
than atropine � |
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Tropicamide�
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d. Retinal examination in adults - much shorter
acting than either atropine or homatropine. � |
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Glycopyrrolate+ �
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a. reduces stomach acid production-used for treating
peptic ulcer in adults b. can use as preanesthetic medication during surgery to dry up mouth, throat & stomach c. during surgey injected to reverse vagal-stimulated bradycardia d. can treat hyperhydrosis too much sweating!!! e. positively charged (unlike atropine, scopolamine) -less CNS side effects � |
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Methantheline+ &
Propantheline+ � |
a. Used for irritable bowel syndrome
b. Block ganglionic transmission and antagonize ACh at muscarinic receptors c. Can be used to treat peptic ulcer but numerous side effects � |
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Side Effects of Anti Muscarinic Drugs
� |
a. Very dangerous in patients with narrow angle glaucoma - antihistamines, phenothiazines, & tricyclic antidepressants have enough antimuscarinic receptor activity to cause atropine- like toxicity
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Contraindications of anti muscarinic drugs
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prostatic hypertrophy, achalasia, intestinal atony
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atropine flush
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1. Indicative of atropine toxicity & especially dangerous in young children
2. Body temp must be reduced (e.g., ice bath) � can't sweat because M receptors on sweat glands are blocked. |
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Nicotine in low doses �
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a. Nicotine is considered a nonselective
nicotinic Receptor agonist, because it binds variety of nicotinic Rc’s b. Nicotine activates nicotinic Rc’s on autonomic ganglia, stimulating transmission through both parasympath & sympath ganglia �c. Cardiovascular effects 1. In a naive individual it can increase total peripheral resistance, stimulate sympathetic ganglia controlling ventricular contraction, & stimulate ganglia controlling venous return - overall effect: elevate blood pressure d. Respiratory System 1. Low doses activate chemoreceptors in aortic arch & carotid body to increase respiration- some direct action on medulla to increase respiration �e. G.I. tract- Parasympathetic has dominant tone in GI tract 1. Low doses can increase G.I. tract motility & HCl release f. Central effects 1. Can cause emesis by acting at chemoreceptor trigger zone 2. Increases ADH release to cause fluid retention � |
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Toxic Effects of Nicotine (high doses)
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a. A ganglionic blocker at high doses
b. Rapidly absorbed through skin & can enter placenta readily c. Kills by causing respiratory arrest 1. In high doses it desensitizes nicotinic receptors at medulla oblongata to stop breathing 2. Desensitizes nicotinic receptors at motor endplate region to cause paralysis of diaphragm & intercostal muscles � |
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DMPP (dimethyl 4-phenyl piperazinium ion) �
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ganglionic agonist
a. Stimulates ganglionic transmission without causing receptor desensitization- only used as laboratory tool b. Specific for nicotinic Rc’s on autonomic ganglia & at the adrenal medulla, not at the NMJ c. Cardiovascular effects- basically same as nicotine �pretty much same as nicotine but isn't toxic(become a blocker) at high doses. |
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Tetraethylammonium+ (TEA)
� |
ganglionic antagonist!
1. Positively charged, so does not cross BBB 2. Short duration of action � |
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Hexamethonium+ (C-6)
� |
ganglionic antagonist!
1. Positively charged, so does not cross BBB 2. Long duration of action 3. Not well absorbed � |
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Trimethaphan+ �
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ganglionic antagonist!
1. Positively charged, so does not cross BBB 2. Short acting 3. Inactive orally & given by IV � |
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Mecamylamine�
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ganglionic antagonist
1. Long-acting, non-charged, can cause CNS effects. Rarely used but still used chronically for hypertension if patient can tolerate side effects (e.g., sedation, tremor, & choreiform movements). � |
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Side Effects �of ganglionic blockers
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a. Block in ganglionic transmission will
interfere with body's ability to maintain homeostasis 1. Abolish autonomic reflexes such as miosis & accommodation of eyes 2. Reduces transmission through division of ANS which is dominant to produce physiological responses (e.g., will generally increase heart rate by blocking dominant parasympathetic tone at SA node) �Also, gastrointestinal tract motility is inhibited, causing constipation. � b. Major side effects - orthostatic hypotension (due to block in sympathetic tone to veins), - urinary retention (due to block in parasympathetic tone) & - impotence due to block in both parasympathetic & sympathetic control of erection & ejaculation � |
