Renal Agents Flashcards
ADH allows for:
Water permeability in the CCT
Alcohol inhibits this
Osmotic Diuretics
Mannitol
Glucose in lumen
Promotes H2O retention in the tubular fluid
Diuretics
Are natureitcs
- loop diuretics
- thiazides
Interfere with active or passive uptake of Na+
Acetazolamide
Carbonic anhydrase inhibitor - inhibits carbonic anhydrase, excreted in PT
Acts on the PT after the glomerulus
Effectiveness decreases after several days because there is enhanced NaCl reabsoprtion at other sites due to bicarbonate depletion
Acetazolamide
Blocks Na bicarbonate reabsorption -> decrease in NaCl reabsorption -> increase in water retention
Might result in:
- hypercloremia
- metabolic acidosis
Mannitol
Osmotic agent
- expands the ECV
- inhibits renin release
Poorly absorbed, so must be given parents rally
Acts in the Thin Descending Limb
Oral Mannitol
Eliminates toxic substances
To potential the effects of K+ binding resins
Furosemide
Loop diuretic
Acts in the Thick Ascending Limb
Blocks the NKCC2 transporter
Thiazides
Make the distal convoluted tubule impermeable to H20
Blocks the Na/Cl transporter = NCC
Adenosine A1 Receptor Antagonists
Caffeine, Rolofyline
Enhances reabsorption of the Na+, counteracts diuresis
Activates tubuloglomerular feedback (TGF)
- stimulates afferent constriction
- decreases GFR
^inhibiting these mechanisms, increase diuretic responsiveness, maintain kidney function
Dorzolamide
Briazolamide
Topical Carbonic Anhydrase Inhibitors
- used to correct for pts with metabolic alkalosis
Adverse effects of carbonic anhydrase inhibitors
Parenthesis
Somnolence
Renal K+ wasting
Allergic Rxns to those sensitive to sulfonamides
Contraindications of Carbonic Anhydrase Inhibitors
Hepatic cirrhosis
Decrease in NH4+ excretion might contribute to hepatic encephalopathy
Osmotic diuretics
Increase H20 secretion in preference to Na+ excretion
- reduces intracranial/intraocular pressure
- removes renal toxins (e.g. post-radio contrast agents)
Toxicity of Osmotic Diuretics (Mannitol)
ECV expansion causes hyponatremia
Headache/Nausea/vomiting
Dehydration
Furosemide, Bumetanide, Torsemide, Ethacrynic Acid
Loop diuretics
2-6 hour until it takes effect
Loop Diuretics
-mide
Blocks the NKCC cotransporter (Na+, K+, 2Cl)
Causes high Mg2+ and Ca2+ excretion!
Develop a positive lumen potential
Furosemide = less toxic, few GI problems, wider dose-response curve
Loop Diuretics
Furosemide/bumetanide/torsemide
- block Tubuloglomerular feedback by inhibiting salt transport in macula densa
- induces synthesis of renal prostaglandins (FGE2) by increasing COX II
> increases blood flow and inhibits transport
NSAIDs ca interfere w/ loop diuretics by inhibiting COX
Uses for loop diuretics
Acute pulmonary edema Edematous conditions Acute Hypercalcemia (Ca2+ wasting) Hyperkalemia Acute Renale Failure Anion OD (bromide, fluoride, iodide)
- not used to treat hypertension bc of short half lives
Thiazides
Block the Na/Cl cotransporter
- increases Na/Ca exchange (enhances Ca reabsorption)
Like CA inhibitors, thiazides have unsubstituted sulfoamide group
Hydrochlorothiazide
Thiazide
Increases Ca2+ absorption
Orally: less lipid like, must be given in high doses
- slowly absorbed, therefore longer duration of action
Indications for thiazides
Hypertension
HF
Neprolitiasis (bc of hypercalciuria)
Thiazides
Act on distal convoluted tubule
Some members retain significant carbonic anhydrase inhibitor activity.
Can be inhibited by NSAIDs.
Thiazide toxicities:
Hypokalemia Metabolic Alkalosis
- Hyperuricemia: Similar to loop diuretics.
- Impaired Carbohydrate tolerance.
- Hyperlipidemia
- Hyponatremia
- Allergic reactions: Since thiazides are sulfonamides
Late Distal Tubule and Collecting Duct
Major site of K+ secretion (where virtually all diuretic-induced changes in K+ metabolism occur) and acidification of urine.
Loop Diuretics are used for..
Think Edema!
- furosemide, torsemide, bumetanide
Action of Loop Diuretic
Blocks the co-transporter NKCC2 in thick, ascending limb
- prevents Na+ absorption
Must monitor the K+ levels = low K+ can cause arrhymias
Action of Loop Diuretic
Think edema, pulmonary congestion
- Blocks the NKCC2 co-transporter
- Induces prostaglandin and NO generation from endothelial cells
- reduces pulmonary congestion and mobilizes fluid out of lung
Furosemide
Most widely used
6 hr duration
Loop diuretic
Ethacrynic Acid
For pts allergic to sulfoamides
- can cause more otoxicity than furosemide
Decreases preload (as a loop diuretic)
Thiazides
Chlorothiazide, hydrocholorthiazide, chlorthalidone, metalazone, indapamide
Thiazide role
Blocks the Na/Cl - NCC cotransporter in the distal convoluted tubule
Used in combo with loop diuretics for those refractory to loops (furosemide)
Side effects of thiazides
Hyperkalemia Metabolic alkalosis Hyponatremia Hyperuricema Hyperglycemia Hypercalcemia
- decreases afterload, therefore the BP is at level where easier pumping blood through
- decreases pulmonary congestion
K-Sparing Diuretics:
Blockers of ENaC and Na+ channel
Trina Terence
Amiloride
K-Sparing Diuretics:
Aldosterone Antagonists
Spironolactone
Eplernone
Direct aldosterone antagonists
- oppose aldosterone in late distal tubule and collecting duct
- prevents myocardial and. Vascular fibrosis
Aldosterone Antagonists: K+ sparing diuretic
Reduce cardiac remodeling
Prevention Na+ retention
Side effects: spironolactone
- gynecomastia
- hypocholremic metabolic acidosis
- hyperkalemia
Diuretic - decrease ECF
Gynecomastia
Endocrine abnormalities
Impotence, benign prostatic hyperplasia - reported with spironolactone
Use eplerenone instead
Side effects of K+ sparing diuretics:
Hypercholermic metabolic acidosis
They inhibit H+ secretion, therefore acidosis might occur
Hyperkalemia: oral K+ should be discontinued if aldosterone antagonists are administered
Gynecomastia - reported with spironolactone
ADH
Increase permeability of principal cells in late distal tubule to water
Increases up regulation of AQP2 channels
Contraindications of K+ sparing diuretics
- chronic renal insufficiency
- Liver disease -> dosing carefully adjusted
CYP34A inhibitors - increase the blood levels of eplerenone
ADH Receptor antagonists = VAPTANS
Treatment of euvolemic hyponatremia
Conivaptan
ADH receptor antagonist
Conivaptan
IV use
ADH receptor antagonist at V1/V2 receptors
Lixivaptan/Tolvaptan
Selective ADH antagonist for V2 receptor
Li+ (demeclocyline)
No selective agent
Decreases production of cAMP
reduces cell responsiveness to ADH
Used to treat SIADH
Clinical Indications of ADH antagonists
- SIADH
- Elevated ADH
Complications associated with diuretic pt 2-3 wks
- initial Na+ loss
- gradually counteracted by antinatriuetric factors (decreasing Na excretion, like aldosterone)
ADH antagonist toxicity
Might cause:
- nephrogenic diabetes insipidus
- renal failure: Li+.demeclocycline causes renal failure
Li+ therapy:
- tremors
- mental obtundation
- cardiotoxicity
- thyroid dysfunction
Spironolactone/Eplerenone
Competitive aldosterone antagonist
K+ sparing diuretic
Eplerenone: more selective and less side effects
Triamtere/Amiloride
Blocks ENaC Na+ channel in apical cells of the collecting duct
K+ sparing diuretic
Spironolactone/Triamtere = dependent on prostaglandin secretion, therefore might be inhibited by NSAIDs
Blockers of ENaC Na+ channel
K+ sparing diuretic
Used to treat hypertension in Liddle Syndrome (where there is an increase in ENaC activity)
Late distal tubule and CCT
Site of aldosterone
Site of K+ secretion
What is aldosterone?
Increases Na+ reabsorption
K+ and H+ secretion
K+ sparing diuretic
Useful in states of:
- mineralcorticoid excess
Primary hypersecretion- Conn Syndrome, ectopic ACTH production
Secondary Aldosteronism: HF, hepatic cirrhosis, nephrotic syndrome
Oral Androgens have…
Low oral bioavailability
- slow and continuously absorbed form
- chemically modified derivative that pay passes liver metabolism
Type A Oral Androgen
Esterification of the C17 hydroxyl group
- longer the chain=more prolonged the action
- more soluble / lipophillic
- must be hydrolysis back to become active
Type B Oral Androgen
Alkylation of C17 alpha
- inhibits hepatic catabolism (bypasses 1st metabolism)
- more suitable for oral
- can bind directly to the androgen receptor
Prolonged use = associated with liver toxicity (cholestasis, pelosis, hepatic cysts, neoplasms
Type C Oral Androgen
Modifications of A,B,C ring
- enhances androgenic potency
- usually occurs with C17 alpha methylation
- increases bioavailability of drug
- increases the half life
- does not make a stronger Kd
Stanozolol, Oxandrolone
Pure anabolic steroids
GnRH androgen synthesis blockers
Leuprolide Gosenelin Buserelin Histrelin “Chemical castration”
Estrogen Treatment - Androgen Synthesis Blocker
Estradiol
Diethylstilbestrol (DES)
Estradiol - negatively feedbacks to inhibit GnRH/LH “chemical castration”
1st generation androgen synthesis blocker
Ketoconazole
2nd generation androgen synthesis blocker
Abiratenone
Inhibitors of DHT biosynthesis
Finesteride
Dutasteride
Side effects of Androgen Therapy
Increase in cholesterol Increase in acne Baldness Liver damage Polycythemia Mood disorders
Increase in BP, fluid retention
Androgen Therapy Side Effects in Males
Decrease size of testes
Decrease sperm
Impotence
Gynecomastia
Androgen therapy side effects in Females
Infertility
Menstrual irregularities
Hisutism
Decrease in breast size
Anti-Androgens
Block the synthesis of androgen
Block the androgen receptor
Used for:
- prostate cancer (initially dependent on androgens for survival)
- benign prostate hyperplasia
- male pattern hair loss
- hirsutism (females)
Castration Levels cause..
<50ng/dL of testosterone
Ketoconazole
1st generation androgen synthesis blocker
- potent, non selective inhibitor of steroid biosynthesis
- inhibits 3/4 of enzymes involved in biosynthesis in Leydig cels
- inhibits CYP3A4
Binds to cytochrome 450 active site
Blocks cortisol/aldosterone synthesis too
Abiraterone
2nd generation
Selective inhibitor of CYP17 in testes and adrenal context
Does not inhibit CYP3A4
“Pyridine moiety”