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34 Cards in this Set
- Front
- Back
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As part of the mechanism of action of corticosteroids, what 3 things do corticosteroids inhibit?
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1) Inhibit action of phospholipase A2
2) Inhibit chemotaxis 3) Inhibit fibroblast activity |
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Other than inhibition as previously mentioned, what are the other 3 mechanisms of action of corticosteroids?
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1) Stabilize lysosomal and leukocyte membranes
2) Increase capillary selective permeability 3) Suppress T-lymphocyte, macrophage activity and IG production |
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True or false. Corticosteroid is a broad spectrum anti-inflammatory agent.
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True
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What is a risk of prolonged corticosteroid use?
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May lead to ACTH depression and atrophy of the adrenal cortex
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What are the 4 mineralocorticoid effects of corticosteroids?
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1) Sodium retention
2) Edema 3) Potassium loss 4) Metabolic alkalosis -Aldosterone! |
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What are 2 side effects of corticosteroid use (not necessarily long term usage...)?
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1) Muscle weakness, wasting
2) Depression of host defenses |
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True or false. Animals on corticosteroids usually appear better because of treatment of the underlying issue.
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False, usually steroids just mask the underlying disorder and will keep getting worse without outward signs resulting in eventual death
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What are 3 strategies to avoid adrenal atrophy from steroid usage?
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1) Administer corticosteroids in morning (evening in cat)
2) Prolonged therapy should be terminated by gradual decrease in dosage over 2 wks or more 3) Avoid long-term therapy w/ long-acting agents |
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What's the purpose of administering glucocorticoids in the morning?
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Try to match the circadian rhythm of the animal (evening in cats) so that the exogenous and endogenous corticosteroids decrease simultaneously so adrenal gland will release ACTH in response
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How is oral absorption of corticosteroids?
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Glucocorticoids are readily absorbed from GIT
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75% of glucocorticoids are bound to _________.
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Transcortin
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What is the affinity of transcortin for glucocorticoids? Capacity?
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High affinity
Low capacity (bc not a lot of endogenous corticosteroids in the body) |
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What % of glucocorticoids are bound to albumin? Affinity? Capacity?
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10-15%, low affinity, high capacity (lots of albumin!)
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What is the physiologically active form of glucocorticoids?
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The 10-15% that's free and physiologically active
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How are glucocorticoids eliminated?
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Metabolized
-First phase reactions and then conjugation to glucoronides and sulfates |
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What are 4 short acting corticosteroids?
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1) Hydrocortisone
2) Prednisone 3) Prednisolone 4) Methylprednisolone |
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The anti-inflammatory effects of corticosteroids have to do with _______ activity.
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Glucocorticoids (not mineralocorticoid activity)
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What is a long acting corticosteroid? What are the glucocorticoid: mineralocorticoid activity ratio?
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Dexamethasone
25: very weak -mainly anti-inflammatory effects |
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Why would you prefer to use prednisone or prednisolone over hydrocortisone?
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Hydrocortisone has 1:1 ratio of glucocorticoid to mineralocorticoid activity ratio
Prednisone and prednisolone 4:.8 so less likely to have adverse effects related to mineralocorticoid activity |
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What are 3 precautions and contraindications of corticosteroids?
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1) Do not combine high doses of corticosteroids with antibacterial agents in the treatment of infections, unless justified
2) In initial treatment of corneal ulcers 3) Identify and correct the primary cause before injecting glucocorticoids into joints |
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There are some safety and efficacy controversies about using corticosteroids with septic/hemorrhagic shock, but if you are going to use steroids when should they be administered?
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Early (within first 2 hours of insult)
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What is meant by a shock dose of corticosteroids?
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Shock doses are much higher than the doses used for inflammation or immune suppression
Shock> immune suppression> anti-inflammatory |
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Why is it so important to administer fluids concurrent with corticosteroid therapy for septic/hemorrhagic shock patients?
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Corticosteroids cause vasodilation and BP will drop if you don't give fluids
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How are corticosteroids administered for patients in shock?
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IV
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What corticosteroid is used for neurological trauma? What is the dose like? How is it administered?
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Methylprednisolone, high dose, IV
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When should corticosteroids be administered for neuroprotective effects? How often is it administered?
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Administer early
Frequent administration based on plasma kinetics |
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What are the neuroprotective effects of corticosteroids?
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Inhibits lipid peroxidation and has an anti-inflammatory effect
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What are 4 antihistamines (autocoid antagonists)?
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1) Diphenhydramine (Benadryl)
2) Dimenhydrate (Dramamine) 3) Clemastine (Tavist) 4) Cetirizine (Zyrtect) |
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What is the mechanism of action of antihistamines?
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Competitive inhibitions of histamine for binding to H1 receptors
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What is oral absorption of antihistamines like?
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Good oral absorption
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How do antihistamines affect the cytochrome p450 system?
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Many induce cytochrome p450 system
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All 4 preparations of antihistamines have the same mechanim of action, so why do some have a more profound sedative effect (Diphenhydramine, clemastine)?
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Depends on the ability to cross the BBB
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What are the 5 pharmacological actions of antihistamines?
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1) Relax contracted bronchiolar and intestinal smooth muscle
2) Inhibit histamine-induced vasodilation and increased capillary permeability 3) Inhibit pruritis and pain sensation 4) Sedation (Diphenhydramine >> cetirizine) 5) Prevent motion sickness |
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What are 2 adverse effects of antihistamines?
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1) CNS depression
2) Antimuscarinic effects -Blocks parasympathetic, so causes things such as dry mouth |
