Medication Summary
The goals of pharmacotherapy are to reduce morbidity, to prevent complications, and to eradicate associated infection. Agents used include antibiotics, loop diuretics, vasodilators, and calcium channel blockers.
Antimicrobials (Antibiotics)
Class Summary
In streptococcal infections, early antibiotic therapy may prevent antibody response to exoenzymes and render throat cultures negative, but may not prevent the development of PSGN.
Penicillin V
Penicillin V is more resistant than penicillin G to hydrolysis by acidic gastric secretions and is absorbed rapidly after oral administration. 250 mg of penicillin V = 400,000 U of penicillin.
Cephalexin (Keflex)
Cephalexin is a first-generation cephalosporin that inhibits bacterial replication by inhibiting bacterial cell wall synthesis. It is bactericidal and effective against rapidly growing organisms forming cell walls.
Resistance occurs by alteration of penicillin-binding proteins. It is effective for the treatment of infections caused by streptococci or staphylococci, including penicillinase-producing staphylococci. It may bed used to initiate therapy when streptococcal or staphylococcal infection is suspected.
Cephalexin is used orally when outpatient management is indicated. It is at least as effective as erythromycin in eradicating GABHS infection.
Erythromycin (E.E.S., Ery-Tab, Erythrocin)
The recommended dosing schedule of erythromycin may result in GI upset, causing one to prescribe an alternative macrolide or to change to thrice-daily dosing. Erythromycin covers most potential etiologic agents, including mycoplasmal species.
Erythromycin is less active against H influenzae. Although 10 days seems to be a standard course of treatment, treating until the patient has been afebrile for 3-5 days seems to be a more rational approach. It inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest. It is indicated for staphylococcal and streptococcal infections.
In children, age, weight, and severity of infection determine the proper dosage. When twice-daily dosing is desired, half the total daily dose may be taken every 12 hours. For more severe infections, double the dose.
Erythromycin has the added advantage of being a good anti-inflammatory agent by inhibiting the migration of polymorphonuclear leukocytes.
Oral erythromycin is an acceptable alternative for patients allergic to penicillin or cephalosporin antibiotics and is effective in the treatment of streptococcal pharyngitis. Erythromycin estolate and erythromycin ethylsuccinate are both effective, although note local antibiotic resistant rates because up to 5% of isolates of S pyogenes may be resistant to erythromycin.
Loop Diuretics
Class Summary
Loop diuretics decrease plasma volume and edema by causing diuresis. The reductions in plasma volume and stroke volume associated with diuresis decrease cardiac output and, consequently, blood pressure.
Furosemide (Lasix)
Furosemide increases excretion of water by interfering with the chloride-binding cotransport system, inhibiting sodium and chloride reabsorption in the ascending loop of Henle and the distal renal tubule.
Furosemide is rapidly absorbed from the gastrointestinal (GI) tract. The diuretic effect is apparent within 1 hour of oral (PO) administration, peaks by the second hour, and lasts for 4-6 hours. After intravenous (IV) administration, diuresis occurs within 30 minutes; the duration of action is about 2 hours; 66% of the dose is excreted in the urine.
Vasodilators
Class Summary
These agents reduce systemic vascular resistance, which, in turn, may allow forward flow, improving cardiac output.
Sodium nitroprusside (Nitropress)
Sodium nitroprusside is a potent, rapidly acting IV antihypertensive agent. Its effect is immediate and usually ends as soon as infusion is stopped because of its rapid biotransformation. Sodium nitroprusside produces vasodilation and increases inotropic activity of the heart. At higher dosages, it may exacerbate myocardial ischemia by increasing heart rate. Use this agent only for treatment of acute severe hypertension or malignant hypertension that is refractory to standard therapy.
Hydralazine
Hydralazine lowers blood pressure by exerting a peripheral vasodilating effect through direct relaxation of vascular smooth muscle. Sodium retention and excessive sympathetic stimulation of the heart may be precluded by coadministration of a thiazide diuretic and a beta-blocker.
Calcium Channel Blockers
Class Summary
In specialized conducting and automatic cells in the heart, calcium is involved in the generation of the action potential. Calcium channel blockers inhibit the movement of calcium ions across the cell membrane, depressing both impulse formation (automaticity) and conduction velocity.
Nifedipine (Afeditab CR, Nifediac, Adalat CC, Procardia, Procardia XL)
Nifedipine is a dihydropyridine calcium channel blocker. The specific mechanisms by which nifedipine reduces blood pressure have not been fully determined but are believed to be brought about largely by its vasodilatory action on peripheral blood vessels. Nifedipine relaxes coronary smooth muscle and produces coronary vasodilation, which, in turn, improves myocardial oxygen delivery.
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Light microscopy (hematoxylin and eosin stain X 25): Photograph showing enlargement of glomerular tuft with marked decrease of urinary space and hypercellularity. The hypercellularity is due to proliferation of endogenous cells and polymorphonuclear leukocyte infiltrate. Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.
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Light microscopy (periodic acid-Schiff stain X 40): Photograph showing enlargement of glomerular tuft with marked decrease of urinary space and hypercellularity. The hypercellularity is due to proliferation of endogenous cells and polymorphonuclear leukocyte infiltrate. Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.
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Immunofluorescence (X25): Fine granular deposits of immunoglobulin G (IgG) along the basement membrane and mesangium, with "starry sky" appearance. Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.
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Ultrastructure (electron microscopy): Photograph showing proliferation of endothelial cells and mesangial cells and leukocyte infiltrate associated with presence of large, subepithelial, electron-dense deposits (ie, "hump") (see arrow). Photograph courtesy of Madeleine Moussa, MD, FRCPC, Department of Pathology, London Health Sciences Centre, London, Ontario, Canada.
