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Aminoglycosides
 

Aminoglycosides

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    Aminoglycosides Aminoglycosides Presentation Transcript

    • AminoglycosidesAminoglycosides The Hashemite University Faculty of Nursing Pharma Project AbdulQadir Nashwan RN.
    • References  Diane S. Aschenbrenner., et al., 2006. Drug Therapy in Nursing. 2nd Ed, Lippincott’s. USA.
    • Outlines Introduction Gentamycin Amikacin Kanamycin Neomycin Streptomycin
    • Introduction  The Aminoglycosides have been in use since 1944.  They are extremely effective antibiotics for treating severe infections.  Their general use, however, is limited because of the potential for serious adverse effects, especially ototoxicity and nephrotoxicity.  Aminoglycosides include gentamicin, amikacin, kanamycin, netilmicin, tobramycin, paromomycin and streptomycin.
    • Introduction  The most frequently used aminoglycosides are gentamycin, tobramycin and amikacin.  Gentamicin is the most widely used, possibly because of its availability as a generic formulation, and its prototype drug for the aminoglycoside family.
    •  Pregnancy Category C  inhibits protein synthesis in susceptible strains of gram- negative bacteria.  Gentamicin must be transported across the cell memb. in order to enter the cell and disrupt protein synthesis. This process requires oxygen; therefore, gentamicin and other aminoglycosides are ineffective against anaerobes. Gentamicin
    • Gentamicin Action  Gentamicin, like all antibiotics, has no direct effect on the cells of the body.  It exerts its effect by entering the bacterial cell and binding to the 30S ribosomal subunit.  This event leads to a misreading of the information used within the cell to form proteins.  The cell then produces amino acids that do not link correctly.
    • Gentamicin  The result is a change in metabolic function that in turn prevents bacterial reproduction and weakens the cell wall, leading to cell wall rupture and death.  Many strains of bacteria are resistant to the aminoglycosides and do not allow them to enter the cell.  Because of this, aminoglycosides are often given with synergistic antibiotics to increase their effectiveness or to alter the cell wall so that the aminoglycoside can enter.
    •  Indications  Gentamicin is effective in managing infections caused by gram-negative bacilli.  Susceptible organisms include: Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli, Klebsiella, Enterobacter, Serratia, and Citrobacter species; and staphylococci (gram+). Gentamicin
    •  Gentamicin is NOT considered useful in treating meningitis unless it is administered intrathecally.  Gentamicin is also indicated for topical treatment of eye or skin infections caused by susceptible organisms. Gentamicin
    •  Clinically, gentamicin is useful for urinary tracts infections (UTIs), such as pyelonephritis, gynecological infections, peritonitis, endocarditis, pneumonia, bacteremia and sepsis, respiratory infections, including those associated with cystic fibrosis, osteomyelitis, and foot and other soft tissue infections associated with diabetes. Gentamicin
    •  Pharmakinetics:  Parenteral genta is widely distributed through the body in ECF; however, it does NOT penetrate appreciably into the CNS.  It crosses the placenta and is secreted in breast milk.  Genta concentrates in the kidney, reaching levels 50 times higher than those in serum. Gentamicin
    •  It is also concentrates in the endolymph and perilymph of the inner ear.  High concentration of genta in these fluids are associated with its major adverse effects “ nephrotoxicity and ototoxicity.  Parenteral genta is excreted unchanged in urine, whereas oral genta is excreted unchanged in feces. Gentamicin
    •  Because it is poorly absorbed when taken orally, genta is usually reserved for parenteral or topical use.  It may, however, be given orally to exert a local decrease in GIT bacteria before surgical or other invasive procedures. Gentamicin
    • o Most Common Adverse Effects: o Nephrotoxicity occurs most frequently in infants or elderly patients, or with prolonged or high-dose therapy. o Ototoxicity occurs most frequently when serum trough levels are elevated, in infants or elderly patients, or with prolonged or high-dose therapy. o Neuromuscular blockade may result in profound respiratory depression. It occurs most frequently in patients with myasthenia gravis and in patients receiving general anesthetics or nondepolarizing skeletal muscle relaxants. Gentamicin
    • CNS: confusion, depression, disorientation, numbness, tingling and weakness. Hemato: leukemoid rxns and depressed bone marrow function. GI: nausea, vomiting, diarrhea, w.t loss, stomatitis, and hepatic toxicity. CV: palpitations, hypotension, hypertension. Hypersensitivity rxns. Other: superinfections, fever, apnea, and joint pain may also occur. Gentamicin
    • Contraindications:  Pregnancy and lactation  Known allergy to any aminoglycoside Cautions:  Renal and Hepatic disease  Dehydration  Pre-existing hearing loss  Myasthenia gravis  Parkinsonism  Infant botulism Gentamicin
    • Maximizing Therapeutic Effects  Make sure that patients receive the full course as prescribed.  Coordinate the administration of drugs to decrease potential drug interactions.  Evaluate C/S reports to make sure that genta is the appropriate drug.  Administer extended penicillins, such as carbenicillin or ticarcillin at least 2 hrs apart to ensure the efficacy of genta. Gentamicin
    • Minimizing Adverse Effects: To reduce the occurrence of adverse effects, it is imperative to maintain blood levels of genta within a therapeutic margin that is very narrow. To do this, Peak and Trough drug levels are monitored throughout therapy. Blood for Peak levels is drawn 30 minutes after the completion of IV administration and 1 hr after IM administration. Bloods for Trough levels is drawn just before the next dose. Gentamicin
    • Monitor for signs of ototoxicity. Before administering each dose, assess the patient’s balance and gross hearing. Monitor for signs of nephrotoxicity. Assess the hydration status of the patient and be alert for dilute urine or proteinuria. Monitor the patient for gentamicin-induced diarrhea because diarrhea may also cause dehydration. Gentamicin
    • If CNS effects occur, safety measures should be instituted to protect the patient. Small, frequent meals can be arranged for patient with GI effects, and frequent mouth care and ice chips can be offered to relieve stomatitis and sore mouth. If a patient receiving genta requires surgery, the chart should indicate prominently that genta has been given. Remember that genta may interact with neuromuscular blocking agents commonly used during surgery. Gentamicin
    • Monitor lab. Tests such as renal and hepatic functions ( KFT & LFT ), Peak and Trough levels of genta, and the fluid intake and output status of the patient. Gentamicin
    • Memory Chip “ GentamicinGentamicin”  Used for serious gram-negative infections.  Major contraindications: hypersensitivity, pregnancy, and breast-feeding.  Most common adverse effects: nausea, vomiting, diarrhea, and w.t loss.  Most serious adverse effects: nephrotoxicity, ototoxicity, neuromuscular blockade.
    •  Maximizing therapeutic effects: administer al least 2 hrs before or after extended infusions of penicillins.  Minimizing adverse effects: monitor Peak and Trough levels throughout therapy.  Most important patient education: teach the patient the S&S of both nephrotoxicity and ototoxicity and also the importance of contacting the health care provider immediately if any symptoms should occur. Memory Chip “ GentamicinGentamicin”
    • AmikacinAmikacin  Amikin ®  Is a parenteral aminoglycoside with a broader spectrum of activity than gentamicin for gram-negative bacilli.  AmikacinAmikacin is also less likely to induce bacterial resistance.  Although some hospitals use AmikacinAmikacin as first-line treatment of systemic infection because of an increased resistance to gentamicin, may others reserve its use for infections that do not respond to other aminoglycoside antibiotics.  Its contraindications, adverse effects, drug interactions, and patient management are similar to those of gentamicin.
    • KanamycinKanamycin  Kantrex ®  Is used orally to reduce ammonia-forming bacteria in hepatic coma and as an adjunctive therapy to decrease GI flora.  It use for systemic infections is limited by the number of bacteria that are resistant to it and the availability of genta in its less expensive generic formulation.  Its contraindications, adverse effects, drug interactions, and patient management are similar to those of gentamicin.
    • NeomycinNeomycin  Mycifradin ®  Has the highest risk for toxicity of all of the aminoglycosides.  Because it is so toxic, it is not administered parenterally.  It is available orally to decrease GI flora as a preparation for bowel surgery and to treat hepatic encephalopathy.  Because it is not absorbed from the GI tract, it frequently causes superinfection within the bowel.  Neomycin is also available in OTC drugs as a topical antibiotic.  Its contraindications, adverse effects, drug interactions, and patient management are similar to those of gentamicin.
    • StreptomycinStreptomycin  Is a parenteral aminoglycoside.  It is used as part of combination therapy for both active TB and for treating streptococcal or enterococcal endocarditis.  As a single agent, it is used for mycobacterial infections, plague, tularemia, and brucellosis.  In addition to ototoxicity and nephrotoxicity, streptomycin may include neurotoxicity.
    • The End