Article Figures & Data
Figures
- FIGURE 1.
Schematic representation of sites of action of different classes of diuretics. Furosemide is loop diuretic acting on thick ascending portion of loop of Henle in nephron.
- FIGURE 2.
Flow chart of renin-angiotensin-aldosterone system response to decreased blood flow (solid lines). Inhibition of this response (dashed lines) can be undertaken by ACE inhibitors acting to prevent conversion of angiotensin I to angiotensin II or by ARBs antagonizing angiotensin receptor at numerous sites of action.
- FIGURE 3.
Schematic representation of release of cholecystokinin to produce gallbladder contraction directly and via vagal afferents. Implications of exogenous sincalide are demonstrated. Relaxation (cholecystokinin) and contraction (morphine) effects on sphincter of Oddi are illustrated. Phenobarbital stimulation of biliary excretion independently of vagal nerve is also illustrated.
Tables
Drug Indication Dose Pharmacokinetics Mechanism of action Contraindications/cautions Adverse effects/interactions Furosemide Diuretic challenge for obstructive uropathy on renal scan 20–40 mg intravenously in adults and 1 mg/kg intravenously over 1–2 min in children Onset, 5 min; peak, 15–30 min; half-life, 1.5–2 h; duration, 2–3 h; 99% plasma protein–bound Loop diuretic that inhibits sodium, potassium, and chloride transport in ascending portion of loop of Henle Contraindicated in anuria, sulfonamide hypersensitivity, and sodium or fluid depletion; caution in kidney or liver disease, diabetes, gout, lupus, pregnancy, and after urologic procedures Tinnitus, allergic reaction, nausea, vomiting, dizziness, blurred vision, headache, hypotension, dehydration; potential interactions with aspirin, diuretics, digoxin, lithium, antihypertensives, and NSAIDs Captopril Renal artery stenosis in renovascular hypertension renal scan 25–50 mg tablet orally 60 min before renal scan Onset, 15 min; peak, 45–70 min; half-life, 2–3 h; duration, 6–12 h; 30% plasma protein–bound Blocks conversion of angiotensin I to II, blocking blood pressure compensation and reducing glomerular filtration Contraindicated in angioedema, high renin levels, dehydration, salt depletion, recent dialysis, aortic stenosis, pregnancy, and hypersensitivity; caution in scleroderma, lupus, depression, diabetes, liver dysfunction, peripheral vascular disease, and dialysis Hypotension, dizziness, tachycardia, chest pain, loss of taste, fever, and rash; can cause dry cough; potential interactions with other ACE inhibitors or ARBs, diuretics, hypertensives, NSAIDs, digoxin, and lithium Enalapril As above Oral dose, 20–40 mg; 0.04 mg/kg in 10 mL of saline intravenously over 3–5 min to maximum dose of 2.5 mg Onset, 60 min; peak, 4–6 h; half-life, 11 h; duration, 24 h; 50%–60% plasma protein–bound; if given intravenously, onset is 15 min and peak effect is at 1 h As for captopril except is ester prodrug converted to enalaprilat in liver after absorption As above As above Duration is period of significant or measurable effect. Some adverse effects are more likely when used therapeutically than in single interventional doses.
Drug Indication Dose Pharmacokinetics Mechanism of action Contraindications/cautions Adverse effects/interactions Sincalide Gallbladder ejection fraction on biliary scan 0.02 μg/kg in 10 mL of saline intravenously over 3–5 min Onset, 5–15 min; peak, 40 min; limited data Synthetic active portion of cholecystokinin that stimulates gallbladder contraction and relaxes sphincter of Oddi Contraindicated in known hypersensitivity, intestinal obstruction, and pregnancy (spontaneous abortion); caution with opioids Abdominal pain, nausea, dizziness, flushing, urge to defecate, and allergic reaction; no documented interactions Morphine Differentiation of acute and chronic cholecystitis on biliary imaging 0.04 mg/kg in 10 mL of saline intravenously over 1–2 min (range of 2–4.6 mg); this is subanalgesic dose Onset, 5 min; peak, 20 min; half-life, 2 h; duration, 20–50 min; 35% plasma protein–bound Opioid agonist that constricts sphincter of Oddi to increase pressure in common bile duct Contraindicated in known hypersensitivity, respiratory depression, and coma; caution in renal or liver impairment, pregnancy, seizures, head injuries, asthma, hypotension, hypothyroidism, pheochromocytoma, addiction, and dyspnea Respiratory depression, hypotension, vomiting, dysphoria, urinary retention, dizziness, sedation, nausea, and constipation; potential interactions with narcotic analgesics, central nervous system depressants, benzodiazepines, and monoamine oxidase inhibitors Phenobarbital Biliary imaging 2.5 mg/kg twice daily orally for 5 d before study Onset orally, 30–60 min; peak, 2–12 h; half-life, 75–120 h; duration, 4 h to 2 d; 5%–60% plasma protein–bound Increases radiotracer uptake and biliary excretion by inducing hepatic enzymes Contraindicated in known allergy to phenobarbital and severe respiratory depression; caution in liver, kidney, or lung dysfunction, elderly, children, and acute pain Sedation, anxiety, respiratory depression, vomiting, dizziness, nausea, headache, and paradoxical excitement; potential interactions with drugs metabolized by liver and central nervous system depressants Duration is period of significant or measurable effect. Some adverse effects are more likely when used therapeutically than in single interventional doses.
