lower cost and some other advantages. although these penicillins are resistant to staphylococcal penicillinase, a few strains appeared, which developed "methicillin resistance not based on penicillinase. Methicillin was the first penicillinase-resistant penicillin and is still used. However, nafcillin is the most potent antibiotic in this group. Methicillin sodium (Staphcillin) is administered intramuscularly or intravenously, and the drug is quite unstable in solution. Its only advantage is in infections caused by staphylococci that are resistant to penicillin G The antibiotic may have some nephrotoxic potential. Nafcillin sodium (Unipen, Nafcil) may be administered orally, intramuscularly, or intravenously. It is more potent than methicillin, it may penetrate the spinal fluid better, and it is largely excreted in the bile. Oxacillin sodium(Prostaphlin, Bactocill) is very similar in actions and indications to nafcillin. It may be given orally or parenterally. Cloxacillin sodium(Tegopen, Cloxapen) and Dicloxacillin sodium ( Dynapen, Dycill) are very similar to oxacillin and are available in capsules for oral administration
lower cost and some other advantages. Although these penicillins are resistant to staphylococcal penicillinase, a few strains appeared, which developed “methicillin resistance” not based on penicillinase. Methicillin was the first penicillinase-resistant penicillin and is still used. However, nafcillin is the most potent antibiotic in this group. Methicillin sodium (Staphcillin) is administered intramuscularly or intravenously, and the drug is quite unstable in solution. Its only advantage is in infections caused by staphylococci that are resistant to penicillin G. The antibiotic may have some nephrotoxic potential. Nafcillin sodium (Unipen, Nafcil) may be administered orally, intramuscularly, or intravenously. It is more potent than methicillin, it may penetrate the spinal fluid better, and it is largely excreted in the bile. Oxacillin sodium (Prostaphlin, Bactocill) is very similar in actions and indications to nafcillin. It may be given orally or parenterally. Cloxacillin sodium (Tegopen, Cloxapen) and Dicloxacillin sodium (Dynapen, Dycill) are very similar to oxacillin and are available in capsules for oral administration
The cephalosporins are B-lactam antibiotics obtained originally from a cephalosporium mold. These antibiotics have the same mechanism of action as the penicillins, but differ in antibacterial spectrum, in resistance to B -lactamase, and also in pharmacokinetics. Whereas the penicillins are derivatives of 6-aminopenicillanic acid, the cephalosporins are derivatives of 7-aminocephalosporanic acid. The related cephamycins have a 7-a-methoxy group which may increase their resistance to B-lactamases The antibacterial spectrum of the cephalosporins is similar to that of the penicillinase-resistant penicillins, except that they are less effective against Hemophilus influenzae, and they are ineffective against pseudomonas several species of Proteus, Klebsiella, B. fragilis, and enterococci Because of their broad antibacterial spectrum and resistance to B-lactamase, the cephalosporins are being greatly overused in clinical situations in which the penicillins would be just as effective and less costly. For example, the cephalosporins do not penetrate well into the cerebrospinal fluid even in meningitis and they do not enter ocular fluids
The cephalosporins are β-lactam antibiotics obtained originally from a cephalosporium mold. These antibiotics have the same mechanism of action as the penicillins, but differ in antibacterial spectrum, in resistance to β -lactamase, and also in pharmacokinetics. Whereas the penicillins are derivatives of 6-aminopenicillanic acid, the cephalosporins are derivatives of 7-aminocephalosporanic acid. The related cephamycins have a 7-α-methoxy group, which may increase their resistance to β-lactamases. The antibacterial spectrum of the cephalosporins is similar to that of the penicillinase-resistant penicillins, except that they are less effective against Hemophilus influenzae, and they are ineffective against Pseudomonas, several species of Proteus, Klebsiella, B. fragilis, and enterococci. Because of their broad antibacterial spectrum and resistance to β-lactamase, the cephalosporins are being greatly overused in clinical situations in which the penicillins would be just as effective and less costly. For example, the cephalosporins do not penetrate well into the cerebrospinal fluid even in meningitis and they do not enter ocular fluids
well The cephalosporins are eliminated both by glomerular filtration and tubular secretion. probenecid prolongs the half-life of these drugs as does renal impairment. The cephalosporins may cause bone marrow depression and some of them, particularly cephaloridine, may cause renal tubular necrosis The cephalosporins are best classified on the basis of their mode of administration. The orally administered members of the group include cephalexin monohydrate(Keflex) cephaloglycin dihydrate(Kafocin), cefaclor (Ceclor), and cefadroxil monohydrate Duricef), The parenteral cephalosporins include cephalothin sodium(Keflin), sterile cephapirin sodium (Cefadyl), Cephacetrile sodium (Celospor), sterile cefazolin sodium (Ancef, Kefzol), cefamandole nafate (Mandol, and the cephamycin cefoxitin sodium(Mefoxin). Finally, cephradine(Anspor, Velosef) can be administered either orally or parenterally. The increasing number of cephalosporins are basically similar in their indications and uses.a physician could become familiar with one oral and one parenteral drug
well. The cephalosporins are eliminated both by glomerular filtration and tubular secretion. Probenecid prolongs the half-life of these drugs as does renal impairment. The cephalosporins may cause bone marrow depression and some of them, particularly cephaloridine, may cause renal tubular necrosis. The cephalosporins are best classified on the basis of their mode of administration. The orally administered members of the group include cephalexin monohydrate (Keflex), cephaloglycin dihydrate (Kafocin), cefaclor (Ceclor), and cefadroxil monohydrate (Duricef), The parenteral cephalosporins include cephalothin sodium (Keflin), sterile cephapirin sodium (Cefadyl), Cephacetrile sodium (Celospor), sterile cefazolin sodium (Ancef, Kefzol), cefamandole nafate (Mandol), and the cephamycin cefoxitin sodium(Mefoxin). Finally, cephradine (Anspor,Velosef) can be administered either orally or parenterally. The increasing number of cephalosporins are basically similar in their indications and uses. A physician could become familiar with one oral and one parenteral drug
without having to learn about all members of the group It should be remembered that these antibiotics should not be considered drugs of first choice in most infections, althoug h they may be very useful in the prevention of infections in surgery. However, for this indication, the cephalosporins should not be given for prolonged periods before and after surg Cephalothin and cephapirin are not significantly different as regards pharmacokinetics, ptency, and indications. Cefazolin gives higher serum levels, although it is bound to proteis to a greater extent and has a serum half-life of 1.8 hours compared to 0.5 hour for cephalothin. It is s aso claimed to penetrate human tissues, such as bone and bile more effectively, although ie does not penetrate int the cerebrospinal fluid The newer cephalosporin, cefamandole and cefoxitin(a cephamycin), may have somewhat greater effectiveness in certain gram-negative bacillary infections but are less active against penicillinase-producing staphylococci. Cefoxitin is the most active drug in this class against b fragilis. There is clearly a clinical equivalence between cephalexin and cephradine, and cephalothin and cephapirin. The newer
without having to learn about all members of the group. It should be remembered that these antibiotics should not be considered drugs of first choice in most infections, although they may be very useful in the prevention of infections in surgery. However, for this indication, the cephalosporins should not be given for prolonged periods before and after surgery. Cephalothin and cephapirin are not significantly different as regards pharmacokinetics, ptency, and indications. Cefazolin gives higher serum levels, although it is bound to proteis to a greater extent and has a serum half-life of 1.8 hours compared to 0.5 hour for cephalothin. It is also claimed to penetrate human tissues, such as bone and bile more effectively, although ie does not penetrate int the cerebrospinal fluid. The newer cephalosporis, cefamandole and cefoxitin (a cephamycin), may have somewhat greater effectiveness in certain gram-negative bacillary infections but are less active against penicillinase-producing staphylococci. Cefoxitin is the most active drug in this class against B.fragilis. There is clearly a clinical equivalence between cephalexin and cephradine, and cephalothin and cephapirin. The newer
cephalosporins, cefamandole and cefoxitin, should be reserved for situations in which they offer clear-cut advantages The aminoglycoside antibiotics-streptomcin, neomycin, kanamycin, gentamicin, and tobtamycin-are bactericidal drugs, which are indicated for the treatment of serious infections caused by many gram-negative bacilli and some gram-positive organisms. However, for the latter indications penicillin and the cephalosporins may be preferable The aminoglycosides have a broad antibacterial spectrum, but streptococci, pneumococci, clostridia, Bacteroides, and fungi are usually resistant. The essential features of several aminoglycosides are shown in Table 53-2. The aminoglycosides include streptomycin, gentamicin, kanamycin, neomycin, tobramycin, paromomycin, and spectinomycin. The most commonly used antibiotic in this group is gentamicin. The aminoglycosides are not absorbed well following oral administration. For that reason they are generally administered intramuscularly or intravenously except in the case of neomycin and paromomycin, which have some
cephalosporins, cefamandole and cefoxitin, should be reserved for situations in which they offer clear-cut advantages. The aminoglycoside antibiotics-streptomcin, neomycin, kanamycin, gentamicin, and tobtamycin-are bactericidal drugs, which are indicated for the treatment of serious infections caused by many gram-negative bacilli and some gram-positive organisms. However, for the latter indications penicillin and the cephalosporins may be preferable. The aminoglycosides have a broad antibacterial spectrum, but streptococci, pneumococci, clostridia, Bacteroides, and fungi are usually resistant. The essential features of several aminoglycosides are shown in Table 53-2. The aminoglycosides include streptomycin, gentamicin, kanamycin, neomycin, tobramycin, paromomycin, and spectinomycin. The most commonly used antibiotic in this group is gentamicin. The aminoglycosides are not absorbed well following oral administration. For that reason they are generally administered intramuscularly or intravenously except in the case of neomycin and paromomycin, which have some