Pharm block 1.txt

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amymafousy
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Pharm block 1.txt
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2010-09-28 01:29:44
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  1. Relation ship of ph with acid/ base absorbption
    • � As pH increases, a weak base will become more and more unionized, lipid soluble and better absorbed
    • � As pH decreases, a weak base will become more and more ionized, lipid insoluble, and will not be absorbed. Also becomes more water soluble and better excreted.
    • � As pH increases, a weak acid will become more and more ionized , lipid insoluble and will not be absorbed. Also becomes more water soluble and better excreted .
    • � As pH decreases, a weak acid will become more and more unionized , lipid soluble and better absorbed
  2. � Absorption
    • � For a weak acid, if pH � pKa is negative it will be more non-ionized and better absorbed
    • � For a weak base if pH � pKa value is positive it will be more non-ionized and better absorbed
  3. � Loading Dose
    • Initial large bolus to create a rapid therapeutic dose.
    • � Loading dose = Vd x Target Concentration/ bioavailability
    • F= 100% if given IV
  4. � Maintenance Dose
    Dose given after Loading dose to maintain a therapeutic dose.Maintainance dose = clearance x target conc/ bioavailability
  5. � Cholinergic Agonists
  6. � Direct acting Cholinergic agonists
    • They act by binding directly to cholinoceptors
    • � Acetylcholine (not used � lots of Adverse reactions)
    • � Bethanechol
    • � Pilocarpine (naturally occurring alkaloid)
  7. �Bethanechol
  8. � Not hydrolyzed by acetylcholinesterases (so long DOA)
    � It has strong Muscarinic action & no Nicotinic action� Actions� Directly stimulates M receptors causing increased intestinal motility & tone� It stimulates detrusor muscle of the bladder while trigone & sphincters are relaxed causing expulsion of urine� Therapeutic Uses:� Paralytic ileus � Urinary retentions
  9. � Pilocarpine
  10. An alkaloid, lipid soluble & is stable to hydrolysis by cholinsterases. It has Muscarinic activity only .
    • Actions-
    • When applied locally to cornea Produces rapid moisis & contraction of ciliary muscle, produces spasm and accommodation & vision is fixed at particular distance making it impossible to focus for far situated objects
    • Therapeutic Use : In Glaucoma
    • It opens trabecular meshwork around schlemm�s canal
    • ? causes drainage of aqueous humor
    • ? IOP immediately decreases.
  11. � Indirect Cholingeric Agonists
    � Cholinesterase inhibitors. Can be reversible or irreversible.
  12. � Irreversible Cholinesterase inhibitors
    • � Ecothiopate
    • � Malathion and Parathion (insecticides)
    • � Sarin (war gas)
  13. � Reversable Cholinesterase inhibitors
    • � Neostigmine (Myasthenia gravis)
    • � Physostigmine
    • � Edrophonium (Tensilon test)
    • � Tacrin (Alzheimer)
    • � Danopezil (Alzheimer)
  14. � Tx of Myasthenia Gravis
    • ? Inhibits cholinesterase enzyme (reversible) --> Higher levels of Ach
    • ? Neostigmine Has a strong influence at the neuromuscular junction
    • ? Pyridostigmine: Has a longer duration of action than neostigmine
    • ? Edrophonium: Diagnostic agent for myasthenia gravis and to diffrentiate myasthenic and cholinergic crisis (Tensilon test )
  15. � Alzheimer's disease
    • � Progressive memory loss
    • � ??? Decrease Ach
    • � Tacrine
    • � Side effect: HepatoToxicity
    • � First drug to treat Alzheimer�s dementia
    • � Given 4x a day (Q.I.D)
    • � Donepezil
    • � Has once-a-day dosing advantage (QD)
  16. � Irreversible cholinestarse inhibitors
    • � Only Irreversible Cholinesterase inhibitor used in clinical practice is Ecothipate, used in Glaucoma. Very long acting
    • � Rest of the drugs are used as pesticides or war gases or poisons: Malathion/Parathion or Sarin
  17. � Acute toxic effects of irreversible cholinesterase inhibitors (OP poisoning )
    • � The dominant initial signs are those of muscarinic excess: miosis, salivation, sweating, bronchial constriction, vomiting, and diarrhea.
    • � Tx: Atropine and Pralidoxime
    • � Treatment of OP poisoning
    • (1) maintenance of vital signs�respiration in particular may be impaired;
    • (2) decontamination to prevent further absorption�this may require removal of all clothing and washing of the skin in cases of exposure to dusts and sprays; and
    • (3) Atropine parenterally in large doses, given as often as required to control signs of muscarinic excess stimulation .
    • (4)Therapy often also includes treatment with pralidoxime (Acetylcholinesterase reactivator)
  18. � Ecothiophate
    • � Irreversible cholinesterate inhibitor.
    • � LONG acting
    • � Used in Glaucoma (closed angle)
    • � Causes miosis of the eye --> increased drainage of aqueous humor
  19. � Cholinergic Antagonists
    • � Can block Muscuranic Receptors
    • � Can block Nicotinic Receptors
    • � Uses of Atropine
    • � Muscuranic Blocker
    • � To produce mydriasis in refraction error testing (short acting preparations of atropine are preferred)
    • � To treat Heart block, Bradycardia
    • � To treat Cholinesterase inhibitors / Oragnaophosphate (OP)pesticides poisoning
    • � Anti-Diarrheal agent
  20. � Other Muscuranic Blockers
    • � Scopolamine: sea sickness
    • � Ipatropium: Asthma (M3 blocker)
    • � Tropicamide: which acts for 4 hours is preferred to produce mydriasis and cycloplegia in refraction error testing and fundoscopy
    • � Benztropine (drug of choice) for treatment of drug-induced Parkinsonism
  21. � Nicotinic Receptor blockers
    • � There are 2 subtypes of Niotinic Receptors:
    • � Nn and Nm
    • � Nn is found in nerves, at the ganglion
    • � Nm is found on muscles.
    • � Nicotinic receptor blockers
    • Ganglionic blocking drugs: Trimethaphen
  22. Neuromuscular blockers
    • :� Nondepolarizing: D-tubocurarine , Atracurium
    • � Depolarizing: Succinylcholine
    • � Ganglionic blockers� Trimethaphen
    • � Nn receptor antagonist. Blocks sympathetic and parasympathetic nervous system
    • � Uses: Hypertensive Crsis�
    • Side effects: Mixed loss of Sympathetic (hypotension) and
    • Parasympathetic Nervous System (tachycardia, constipation, urinary rentention, dry mouth, etc�)
    • � Neuromuscular blockers
    • * Nm blockers blocks acetylcholine at the Nm receptor. Used in Surgery for skeletal muscle relaxation
  23. � Non-depolarizing
    • � Long acting: Tubocurarine (ADR: Nn blockage)
    • � Intermediate acting: Atracuriun (safe in pts with renal insufficiency)
    • � Short acting: Miyacurium
  24. � Depolarizing:
    • Succinylcholine (shorting acting)*
    • ADR: Succinyl apea* Malignant hyperthermia (tx by dantrolene)
  25. � alpha 1 Selective Agonists
    • � Phenylephrine :
    • � MOA: Alpha 1 receptor agonist
    • � Very low Bioavailability
    • � Causes vasoconstriction of vessels.
    • � Nasal and ophthalmic preparations.
    • � Uses:
    • � Nasal Decongestant
    • � Mydriasis (doesn�t cause cycloplegia)
    • � Side effects/Contraindications: Closed angle Glaucoma. Rebound congestion.
  26. � Dopamine
    • � At low concentrations: Stimulates D receptors, causes Vasodilation of
    • arteries (renal, coronary, GI)� At intermediate doses: Stiumates Beta 1
    • receptors --> tachycardia� At high doses: � stimuates alpha 1
    • receptors ? Vasoconstriction� Uses: Cardiogenic shock (beta 1
    • stimulation), CHF, Hypotension (alpha 1 stimulation)� Adverse effects:
    • HTN, Tachycardia, arrythmias
  27. � Beta 2 agonists
    • � Terbutaline � used in
    • pre-term labor. Causes smooth muscle relaxation in the uterus.�
    • Ritodrine � Also used in preterm labor� Albuterol, Salmeterol � Used in
    • asthma. Causes tremers.
  28. � Adrenergic Antagonists
    • � Alpha antagonists�
    • Non-selective (phentalamine, phenoxybenzamine)
    • � Alpha 1 selective (-sin,-cin)
    • � Alpha 2 selective (Yohimbin)
    • � Beta antagonist (-olol)� B1
    • selective (ABEAM)
    • � Non-selective (the rest)
    • � Alpha + beta antagonists
    • (labetolol)
  29. � Phenoxybenzamine
    � Uses: Pheochromocytoma� Non-competitive inhibitor
  30. � Alpha 1 selective blockers
    • � -Sin, -Cin� --> decrease in BP (not the DOC Of HTN)� --> inrease
    • urinary flow (not the DOC of urinary rention)� Used in a patient if
    • they have BOTH hypertension and urinary rentention (2ndary to BPH)
  31. � Beta blockers
    • � Cardioselective beta-blockers (ABEAM)
    • � Decreases HR � used in treatment of HTN
    • � Beta non-selective (Timolol)
    • � Used topically for tx of Glaucoma
    • � ADR:
    • � Mask the sign of hypoglycemia (All beta blockers)
    • � --> asthma (Beta non-selective blockers)
  32. � Glaucoma
    • Types of Glaucoma:
    • 1. Open Angle Glaucoma � Excessive production of Aqueous Humour
    • 2. Closed Angle Glaucoma � Outflow obstruction of Aqueous Humour
    • Two Therapy aimed at:
    • 1. Reduce (Production, Synthesis or Secretion)
    • Acetazolamide, Timolol, and, Mannitol
    • 2. Facilitate the drainage(drugs that causes miosis): Pilocarpine, Carbachol, Ecothiopate, and Mannitol
  33. � Treatment of Open Angle Glaucoma
    • � Goal is to reduce synthesis of the aqeuous humor
    • � Carbonic Anhydrase Inhibitors: Mannitol Is also an osmotic agent that increases drainage
    • Acetazolamide (oral), Dorzolamide (topical )
    • � Reduces the secretion/synethesis:Timolol topical eye drops Non-selective beta
    • blockade and Betaxolol eye drops Selective beta1 blockade
  34. � Treatment of Closed Angle Glaucoma�
    • Pilocarpine, Carbachol, Ecothiopate and Physostigmine :Causes Ciliary muscle contraction, increases Irido-corneal angle and open trabecular meshwork.
    • � Mannitol: acts as an osmotic agent, attracting water, and increases drainage of aqueous humor
    • � Prostaglandins : Latanoprost : increase the outflow through uveoscleral meshwork
  35. � Drugs used to Treat Asthma
    • � Beta Agonists (albuterol, salmeterol)- ADR: Tremors
    • � Cholinergic antagonists
    • � Steroids (inhaled Beclomethasone or oral prednisone)- Oral Candida or Cushings
    • � Xanthine derivatives (Theophylline): ADR: increased urination, cardiac/CNS toxicity
    • � LT receptor blockers (Zafirlukast)
    • � LT synthesis inhibitor - inhibits LOX enzyme - Zileuton
    • � Mast cell stabilizers
    • � Sodium cromoglicate

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