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This document provides an overview of different types of anesthetic protocols, including conscious sedation and various IV and inhaled anesthetics. It also explains the mechanisms of action for some general anesthetics, highlighting their roles in the central nervous system.
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Maintenance Barbiturates - Thiopental, Methohexital Provides sustained anesthesia - Replaced by propofol...
Maintenance Barbiturates - Thiopental, Methohexital Provides sustained anesthesia - Replaced by propofol BZDs - Commonly used in the perioperative period include midazolam, lorazepam, and less Recovery frequently diazepam Time from discontinuation of anesthetic until consciousness - Produce minimal depression of ventilation, and protective reflexes return although transient apnea may follow rapid IV administration of Midazolam for Anesthesia Protocols induction of anesthesia Etomidate - GABA-mimetic - An IV anesthetic with hypnotic but not For minor procedures analgesic effects and is often chosen for Conscious sedation techniques (IV agents with local its minimal hemodynamic effects anesthetics) Ketamine - NMDA receptor inhibitor For more extensive surgical procedures - Partially water-soluble; highly lipid-soluble IV drugs to induce the anesthetic state, inhaled anesthetics phencyclidine derivative (with or without IV agents) to maintain an anesthetic state, - Produces significant analgesia and neuromuscular blocking agents to effect muscle - “dissociative” anesthesia” – cataleptic state relaxation - S(+) form is more potent than R (-) isomer Dexmedetimidine - Highly selective α2-adrenegic agonist Assessment of depth of anesthesia during surgery - Principally used for the short-term sedation Vital sign monitoring of intubated & ventilated Cerebral monitoring (EEG) Opioid Analgesics - Strong opioids (morphine, fentanyl, sulfentanyl) Mechanism of Action in General Anesthetics - Analgesic agents and are distinct from Anesthetics = CNS depressant general anesthetics and hypnotics Increase inhibitory (GABA) synaptic activity - Routinely used to achieve postoperative Inhaled anesthetics, Barbiturates, BZDs, Etomidate, analgesia and intraoperatively as part of a balanced anesthesia regimen and Propofol Decrease excitatory (glutamate or ACh) synaptic activity Local Anesthetics Inhaled anesthetics (Nicotinic receptor antagonists) Ester Type: 1i - Cocaine Ketamine (NMDA receptor antagonist) - Procaine - Chloroprocaine Inhaled Anesthetics Amide Type: 2i - Lidocaine Nitrous Oxide - Non-volatile gas - Bupivacaine - Weakest anesthetic; potent analgesic - Prilocaine Desflurane - Popular anesthetic for out-patient procedures MOA: blockade of voltage-gated sodium channels Sevoflurane - AOC: children (less pungent) Isoflurane Factors that determine systemic absorption of local anesthetics: Enflurane - AOC: for asthmatic patient Halothane - AOC: children (less pungent) Dosage - Most hepatotoxic Site of injection Methoxyflurane - Potent anesthetic; weakest analgesic Drug-tissue binding - AOC: during labor Local tissue blood flow The rest is volatile liquids Use of a vasoconstrictor (e.g. epinephrine) - downward direction (N to M): increasing potency Physicochemical properties - upward direction (M to N): increasing MAC Note: MAC – is the median effective dose (ED50) of the anesthetic, Toxicities: expressed as the percentage of gas in a mixture required to achieve that effect Systemic toxicity Toxicities: CNS toxicity Acute Toxicity sedation, light-headedness, visual and auditory - Nephrotoxicity disturbances and restlessness metabolism of enflurane and sevoflurane may generate Cardiotoxicity compounds that are potentially nephrotoxic Bupivacaine – most cardiotoxic enflurane with prolonged exposure – significant renal injury Local toxicity - Hematoxicity nitrous oxide – megaloblastic anemia Neural injury - Hepatotoxicity local anesthetic agents were potentially neurotoxic Halothane hepatitis durocaine – a spinal anesthetic formulation - Malignant hyperthermia containing procaine important cause of anesthetic morbidity and mortality Transient Neurologic Symptoms (TNS) Chronic Toxicity Syndrome of transient pain or dysesthesia has - Mutagenicity, teratogenicity, carcinogenicity been linked to use of lidocaine for spinal anesthesia Intravenous Anesthetics Propofol - Most frequently administered for induction DRUGS USED TO TREAT DISEASES OF THE BLOOD, of anesthesia INFLAMMATION, & GOUT - Also used for maintenance of anesthesia (continuous infusions) - Milky white appearance; slightly viscous; COAGULATION DISORDER pH ~7 - Formulated as an emulsion containing: Hemostasis 10% soybean oil Balance 2.25% glycerol Vascular event: vasoconstriction 1.2% lecithin Cellular event: platelet migration and aggregation susceptible px may experience allergic reactions Protein event: coagulation factor cascade - Act as hypnotic but does not have analgesic properties Stimuli - Has antiemetic action Endothelial injury Fospropofol - A water-soluble prodrug of propofol Presence of Foreign bodies rapidly metabolized by alkaline Stasis of blood phosphatase, producing propofol, Arterial clots: platelet-rich “white thrombi” phosphate, and formaldehyde - Licensed by the FDA in 2008 as a sedating Venous clots: fibrin-rich “red thrombi” agent for use in adult patients during monitored anesthesia care Coagulation Cascade Module 4 – Pharmacology Page 17 of 33 RJAV 2022 - Given as IV infusion for post angioplasty to prevent acute thrombosis Adenosine and Dipyridamole Phosphodiesterase - MOA: inhibits adenosine uptake, inhibitor CGMP phosphodiesterase and CAMP phosphodiesterase - Use: Primary and Secondary prevention of acute myocardial infarction (only effective if given with other antiplatelet or anticoagulant drugs) - Adverse effects: “coronary steal” phenomenon Cilostazol - Effect: vasodilator - Use: intermittent claudication Anticoagulant Direct thrombin inhibitor MOA: - Interfere the coagulation cascade - Inactivate of inhibit factor II-a directly Parenteral Hirudin Intrinsic pathway: XII, XI, IX, X - natural product from Leeches Extrinsic Pathway: III, VII X Lepirudin - recombinant form; clinically used; DOC for HIT or Heparin induced Dissolution thrombocytopenia Bivalirudin - small molecule that inactivates factor II-a; used as a antithrombotic post angioplasty Argatroban - alternative in the management of HIT Oral Dabigatran - Oral factor II-a inhibitor - Prophylaxis against VTE - Substitute or Alternative for warfarin - Adverse effects: bleeding - Drug interaction: CYP3A4 inhibitor Indirect Thrombin MOA: inhibits factor synthesis or formation of inhibitors active clotting factors (factor II-a) Parenteral Heparin - Sulfated mucopolysaccharide; released by platelets Anti-thrombotics - 2 forms: Anti-platelet Aggregants - High molecular heparin/ Regular/ Thromboxane synthesis Aspirin Unfractionated inhibitor - Low molecular heparin/ Fractionated MOA: Heparin - inhibits COX of platelets, therefore Regular/ HMWH/ Unfractionated Heparin decreasing levels of TXA2; (UFH) Irreversibly acetylates COX of - MOA : binds and forms an active platelets complex with anti thrombin or anti - For primary and secondary thrombin III prevention of acute myocardial - Monitoring parameters : aPTT / PTT infarction LMWH/ Fractionated Heparin and Analogues - Secondary prevention of stroke - MOA : forms active complex with antithrombin III Adverse effects: bleeding, GI intolerance, - Enoxaparin, Dalteparin, Tinzaparin ulcer, bronchospasm, hypersensitivity, - Fondaparinux (synthetic salicylism polysaccharide ADP inhibitor Thienopyridines - Ticlopidine, Clopidogrel, Prasugrel Uses: (HMWH and LMWH) - Given in for primary and secondary - When coagulation is needed for prevention of acute myocardial pregnancy (LMWH – choice for infarction (given at least 9 months pregnant women) after ACS) - When initiating anticoagulant therapy - Given post- angioplasty - Management of ACS (DOC: LMWH) - MOA: irreversible inhibitor of P2Y12 - Management of VTE (venous receptor thromboembolism) - Adverse effects: Adverse Effects: Ticlopidine : causes - Bleeding (antidote: Protamine thrombocytopenia, neutropenia, risk sulfate) of thrombotic thrombocytopenic - HIT purpurea - Osteoprosis Oral Non-Thienopyridines Oral anti-factor Xa - Ticagrelor – Given for post- - Direct factor Xa inhibitor angioplasty (to prevent acute - Rivaroxaban, Apixaban thrombosis) - Used in the management of venous GIIb / IIIa inhibitors MOA: blocks the G II b / III a receptor to thromboembolism prevent platelet cross-linking or aggregation - Less adverse effects Older agents - Abciximab, Eptifibatide, Tirofiban - VKORC (vitamin K epoxide reductase) inhibitor Module 4 – Pharmacology Page 18 of 33 RJAV 2022 - MOA: inhibits Vitamin K epoxide - Evolocumab, Alirocumab reductase resulting to inhibition of - MOA: inhibits PCSK9 resulting to increase in LDL receptors formation of active Vitamin K allowing increase in hepatic and tissue uptake or utilization of - Examples : Dicumarol, cholesterol Phenprocoumon, Indanedione - Evolocumab – used in the management of hypercholesterolemia (Phenindione, Anisindiones), that is refractory to other drug Warfarin - Adverse effects : Bleeding, RHEUMATOLOGIC DISORDERS Intracerebral hemorrhage, Abnormal bone development, Cutaneous necrosis Inflammatory Warfarin Autoimmune - Monitoring parameter: PT-INR Affects the muculoskeletal system - PT INR: < 2 : underdose | >3 Joints overdose Muscles Fibrinolytic Bones MOA: Activate the fibrinolytic system by conversion of the inactive Tendons and Ligaments proenzyme, plasminogen into the active enzyme plasmin, that degrades fibrin Streptokinase Source: Beta hemolytic streptococci INFLAMMATION Adverse effects : bleeding, hypersensitivity A non-sprecific immune reponse against an adverse Note: stimulus. - give premeds before running Microbial invasion infusion: antihistamine, Physical injury glucocorticoids Purpose: For protection and a part of healing process - avoid subsequent exposures APSAC Aminosylated plasminogen streptokinase activator complex Cardinal Signs of Inflammation Recombinant t-PA Alterplase, Teneclepase, Reteplase Used in the management of acute venous thromboembolism Within 3 hours of an acute ischemic stroke Within 30 mins of an acute myocardial infarction that is ST segment elevated Pro Coagulant Vitamin K - 3 forms : Vitamin K1 (phylloquinone or phytonadione); Vitamin K2 ( menaquinone); Vitamin K3 (menadione) - Used in the management of bleeding secondary to Vitamin K deficiency - Prevent hemorrhagic disorder in the newborn Epsilon Tranexamic acid (analogue) Calor Tumor Functio laesa aminocaproic acid MOA: inhibits the action of tPA and uPA Aprotein MOA: directly inhibits plasmin Rubor Dolor Used in the management of t-PA-associated bleeding Autoimmune Diseases DYSLIPIDEMIA Arise from overreactive immune response Abnormal lipid profile T cells Hypercholesterolemia: ↑ LDL ± ↓ HDL B cells Hypertriglyceridemia: ↑ Serum triglyceride Adversely target substances and tissues normally present in the body Drugs for Dyslipidemia HMG-COA reductase Inhibitor Rheumatologic Diseases: - MOA: inhibit the first committed step in cholesterol biosynthesis - Cholesterol synthesis: peaks at height of sleep Rheumatoid Arthritis – affects the synovium - Examples: (-statin) Arthritis – multiple, symmetrical Long acting (anytime) : Atorvastatin, Rosuvastatin Morning joint stiffness – (~1 hour) Short acting (at bedtime) : Simvastatin, Pravastatin Hand involvement - Adverse effects: Myalgia, Muscle pain (Myositis) , Rhabdomyolysis Fibric acid derivative Osteoarthritis – most common - MOA: increase activity of the enzyme lipoprotein lipase (LPL) Non-inflammatory - LPL: takes up and breaks down triglyceride into fatty acid and Not an autoimmune disease glycerides or glycerol = lowers serum triglyceride - Examples: Fenofibrate, Gemfibrozil Systemic Lupus Erythematosus - Use: Drug of choice in the management of hypertriglyceridemia “Lupus” - Adverse effects: Myositis, Myalgia, Rhabdomyolysis Butterfly-shaped rash Nicotinic acid Photosensitivity - A form of niacin - MOA: inhibits synthesis and release of VLDL from the liver Renal complications: Nephritis - Use: alternative to fibrates for hypertriglyceridemia - Adverse effects: hepatotoxicity at high doses, flushing Ankylosing Spondylitis Bile acid binding resins or Bile acid sequestrant Bamboo spine - Cholestyramine, Colestipol Enthesitis - MOA: inhibits recycling of bile acids Sacrolitis - Use: add-ons of statins Cholesterol transport inhibitor Drugs/ Agents - MOA : inhibits intestinal cholesterol uptake is mediated by NPC1L1-like transporter (Niemann Pick C1-Like-1) - Ezetemibe ANALGESICS - Used as an add-on for statins PCSK9 inhibitors Analgesia – loss of pain perception - Proprotein convertase subtilisin/kexin 9 (PCSK9) Module 4 – Pharmacology Page 19 of 33 RJAV 2022 NON-NARCOTICS Anti-inflammatory: 3.2-4 g/day - MOA : COX inhibition P-aminophenol Derivatives Anti-pyretic: 0.3-1.2 g/day - MOA : inhibits response to IL-1 and Acetaminophen or Paracetamol (Tylenol ®) cutaneous vasodilation Weak prostaglandin synthesis inhibitor in the periphery Anti-platelet: NMT 325 mg/day (COX inhibitor) - MOA : COX inhibition in the platelets → TXA2 Antipyretic activity (Potent aggregant) synthesis inhibition Lacks anti-inflammtory activity even at higher doses - ↓dose :↑ antiplatelet 1st line for OA - anti-aggregation = bleeding substitute for Aspirin Anticancer: potential use - Chronic inflammation (overexpression of Advantage: safe in pregnant and lactating women and COX-2) → Cancer among children Hepatotoxicity Toxicities: Risk factors: Gastric effects: dose > 5 mg/kg/day - gastritis, gastrointestinal bleeding (COX-1 pre-existing liver disease inhibition) concomitant use of CYP1A2 inducers - Treatments: PPI’s – 1st line NSAIDs Misoprostol – alternative Weak organic acids EXCEPT Nabumetone which is Reversible Decrease in GFR: metabolized into acetic acid derivatives - renal vasoconstriction → low GFR COX inhibitors → inhibits Hypersensitivity reaction: Prostaglandin - NSAID-induced Bronchial Asthma synthesis - Treatment: Zileuton, Montelukast, Zafirlukast Cyclooxygenase (COX) Enzymes - ASA Hypersensitivity Syndrome – Nasal polyposis, Chronic sinusitis Effects in Serum Uric Acid Levels - Aspirin, Tolmetin, Salicylates - < 2g/day: decreased renal excretion of urate → Antagonize uricosuric effect of uricosurics - C/I in Gout patients taking uricosurics CNS effects (ASA, Salicylates) - Mild: salicylism – hyperthermia, tinnitus, hyperventilation - Severe: acid-base imbalances, hallucination Cyclooxygenase (COX) Enzymes - Fatal: Respiratory depression Reye’s syndrome (ASA) NSAIDS – reduced prostanoid - Children: with Fever, Viral infection + ASA production and thus PGE2 for - Hepatic Failure instance will be lower - Encephalopathy (brain damage) Pyrazolones Phenylbutazone Dipyrone Sulfinpyrazone – Not an NSAID, Uricosuric Powerful analgesia and inflammatory Toxicities: Hemtologic: Isoforms of COX: - Thrombocytopenia (low platelet), Aplastic 1. COX-1 anemia (↓platelet, ↓RBC, ↓WBC), Agranulocytosis (↓granulocytes: BEN) Constitutive Enzymes Nephrotoxicities: PGs for homeostatic functions (e.g., gastroprotection) - Acute Tubular Necrosis, Anasarca (massive edema), Nephrotic Syndrome 2. COX-2 Indole Indomethacin Inducible Enzymes PGs for inflammation (PGE2) - Blocks COX-1 > COX-2 - High risk of GI effects Uses: NSAIDs - To enhance closure of Patent Ductus Arteriosus) Non-Selective COX inhibitors - Management of Bartters Syndrome (defect in Aspirin the reabsorption of electrolyte by the kidney) Pyrazolones - Treatment of pain in acute gout Indole Pyrrole Alkanoic Tolmetin Acid - C/I: Gout Pyrrole Alkanoic Acid Phenylacetic True phenylacetates: Phenylacetic Acid Acids - Sulindac Fenamates - Alclofenac Oxicam - Diclofenac Propionic Acids Acetic acid derivatives: - Ketorolac Specific COX-2 Inhibitors - Etodolac - Nabumetone Celecoxib Etoricoxib Sulindac – SJS/TEN Valdecoxib Ketorolac – treatment of pain after surgery Rofecoxib Fenamates Mefenamic acid - Advantage: less associated to gastric effects Meclofenamate - Increased risk of acute thrombotic events Flufenamic acid - Analgesia only Non-selective COX Inhibitors: - Used for NMT 5 days (acute pain) - Never given in children Aspirin Prototype; Irreversible COX inhibitor - Safest for children: Ibuprofen Oxicam Piroxicam Pharmacodynamics : - Bleeding and ulceration are more likely to Analgesic: >> COX-2 sites of the brain (central) and COX inhibition - highest risk of GI effect (peripheral) Module 4 – Pharmacology Page 20 of 33 RJAV 2022 Propionic Acids Ibuprofen Hyperventilation Naproxen Mydriasis Ketoprofen RhinorrheaHostility Flurbiprofen Contraindications Head trauma Pregnancy - Analgesic and anti-inflammatory D/I with full & partial agonists → - Ibuprofen and Naproxen: additional Antagonistic antipyretic - Naproxen: used for fever of malignancy Classifications: NARCOTICS Opiates Opioids Narcosis Based on Sources Synthetic Insensibility Stupor Opioid Agonists Strong Full Agonists Based on Mild to Moderate Full Agonist Papaver somniferum Pharmacodynamics Partial Agonist Brown gum → crude opium Opioid Antagonist Morphine (10%) Mechanism of Actions: Based on sources Opiates – Natural opium alkaloids 1. Opioid Peptides – endogenous Morphine - Standard comparison as analgesic Opioid-like pharmacologic properties: - Undergoes extensive first-pass effect Endorphins Enkephalins Codeine Met-enkephalin - Standard of comparison as antitussive Leu-enkephalin - Less effective than Morphine Dynorphins Thebaine - Precursor in the synthesis of Naloxone 2. Opioid Receptors Opioids Majority of opioid-mediated effects Semisynthetic: Mu: Heroin Analgesia - Diacetylmorphine/diamorphine Euphoria - common drug of abuse Miosis Constipation Apomorphine Respiratory depression - not an analgesic Kappa: - Dopaminergic: DA reuptake inhibitor; D2 agonist - Emetic Additional analgesia in women - Management of Parkinsonism Delta: Spinal analgesia Semisynthetic Morphine Derivatives Modulation of hormone and neurotransmitter release - Hydroxymorphone, Oxymorphone - 8-12x more potent than Morphine Opioid Agonists Mechanism of Action Stimulate the release and mimic the action of Semisynthetic Codeine Derivatives endogenous opiod peptides - Hydroxycodone, Oxycodone Actions Central - 8-12x more potent than Codeine Analgesia Synthetic: Euphoria Methadone Miosis - similar efficacy with Morphine Cough suppression - longer DOA Respiratory depression - less rapid development of tolerance Emesis - to wean off patients addicted to Morphine or Heroin Peripheral Meperidine (aka Pethidine) Constipation - no cardia or biliary effect Hypotension - converted to Normeperidine Bradycardia - used for acute pain only Histamine release - A/E: seizures Tocolysis Biliary contraction Levorphanol Clinical Uses Analgesics - 5-7x potent than Morphine Mild – Tramadol - D-isomer: Dextrometorphan Moderate – Codeine - Antitussive Severe – Morphine Management of acute pulmonary Loperamide & Diphenoxylate edema – Morphine - antidiarrheals Ability to reduce anxiety effect Diphenoxylate Can lower afterload and preload - causes addiction Anesthetic adjuncts - co-administer with Atropine Antidiarrheals Diphenoxylate Tramadol Loperamide - mild pain Antitussives - derivative of codeine Dextromethorphan Fentanyl & related drugs Toxicities Respiratory depression - Alfentanyl & Sufentanyl greatest threat - 100x more potent than Morphine Increase in Intracranial Pressure C/I: head trauma Pentazocine Tolerance: - partial kappa agonist 2-3 weeks of chronic use Physical dependence withdrawal symptoms: Frequent yawning Module 4 – Pharmacology Page 21 of 33 RJAV 2022 Based on Pharmacodynamics - Management of severe hyperuricemia; Strong Full Agonists Morphine and related drugs reduce risk of urate stone formation Fentanyl - Prevent or Management of Tumor Lysis Heroin syndrome Methadone - Adverse effect: Rash or SJS-TEN); Oxymorphone Aplastic anemia; Hepatitis; Renal failure Hydromorphone Febuxostat - Indication: the same as allopurinol Meperidine - Used if patient cannot tolerate allopurinol Levorphanol - Advantage: not associated with SJS-TEN Mild to Moderate Full Agonist Codeine and related drugs - Adverse effects: increase cardiovascular Hydrocodone mortality, myocardial infarction Oxycodone - Contraindication: CAD Tramadol Xanthine oxidase MOA : facilitate conversion of urate to a more Partial Agonist Nalbuphine inhibitors soluble product, allantoin. Butorphanol Recombinant Urate Oxidase Pentazocine Buprenorphine Pegloticase Opioid Antagonist - Treatment of Narcotic - For patient with refractory poisoning - CI: presence of G6PD deficiency Rasburicase Naloxone - Used in patients who are at risk of Naltrexone developing tumor lysis syndrome Nalorphine - Management of elevated uric acid levels Nalmefene - Adverse effects: hemolytic anemi Levallorphan DMARDs GOUT Disease-modifying antirheumatic drugs Metabolic disorder Chemically diverse agents Increase deposition of monosodium urate crystals in the Alter or reverse disease progression tissue + hyperuricemia (increase of total uric acid in the body Aka SAARDs (Slow – acting ARDs) Signs and symptoms : Full effect: 6–12 months Acute arthritis : Cardinal features of inflammation ( rubort, tumor, Classifications: calor, function laesa) Small molecule drugs usually monoarticular ( one joint | 1st Nonbiologic Agents Metarsophalangeal joint) In elderly women : polyarticular usually arthritic Large molecule drugs joint Biologic Agents Recombinant DNA technology Chronic gout : (+) tophus – subcutaneous deposit of MSU crystal Nonbiologic Agents (+) gouty nephropathy – form of chronic kidney Methotrexate - 1st line DMARD disease - MOA: blockade of AICAR transformylase (+) uric acid stone formation and Thymidylate synthetase → ↑ AMP → enhance release of Adenosine Drugs for Gout - Hence: inhibition of inflammation Acute Gout - blocks chemotaxis Pain control - NSAIDs (except aspirin and salicylates) - low dose; higher doses = anticancer - Drug of choice: short acting and lipid effect soluble Antimalarials - 2nd line DMARDs - Indomethacin - Hydroxychloroquine, Chloroquine - Ibuprofen - MOA: blocks T lymphocyte responses to - Diclofenac mitogens; inhibits chemotaxis and inhibits Anti-inflammatory Colchicine DNA & RNA synthesis - MOA: inhibits microtubule synthesis - T/E: Optic neuritis, cinchonism (tinnitus, - Adverse effects: hematologic (aplastic headache, dizziness) anemia, hemolytic anemia, Gold Compounds - Parenteral: Aurothiomalate, thrombocytopenia); acute hepatitis; renal Aurothioglucose failure; bloody diarrhea - Oral: Auranofin - Contraindication: elderly, presence of renal Sulfasalazine - Metabolized to: Sulfapyridine (active for failure DMARD), 5-aminosalicylate - Note: Diarrhea is the first indication of (Meselamine: IBD) toxicity - A/E: Nausea and vomiting, skin rashes Oral glucocorticoids and discoloration, hematotoxicities - Prednisone Leflunomide - metabolized to: A77-1726 - For polyarticular arthritis in elderly patients - inhibits dihydroorotate dehydrogenase Adrenocorticotropic hormone (IM ACTH) - inhibits ribonucleotide synthesis - For refractory polyarticular acute gout for elderly patients with renal failure Biologic Agents Chronic Gout Abatacept - T cell modulating biologic Hypouricemic therapy - inhibits activation of T cells - Goal : decrease serum uric acid;