Antibacterial Drugs Pharmacology Cheat Sheet

Antibacterial drugs, also known as antibiotics, are drugs that either kill bacteria or inhibit the growth of bacteria. They’re mainly used to treat systemic (involving the whole body rather than a localized area) bacterial infections. Antibacterial drugs include:

• Aminoglycosides
• Penicillins
• Cephalosporins
• Tetracyclines
• Clindamycin
• Macrolides
• Vancomycin
• Carbapenems
• Monobactams
• Fluoroquinolones
• Sulfonamides
• Nitrofurantoin.


Antibacterial drugs


Aminoglycosides are bactericidal (they destroy bacteria). They’re effective against:
• Gram-negative bacilli
• Some aerobic gram-positive bacteria
• Mycobacteria
• Some protozoa.

Aminoglycosides currently in use include:
• Amikacin sulfate
• Gentamicin sulfate
• Kanamycin sulfate
• Neomycin sulfate
• Netilmicin sulfate
• Paromomycin sulfate
• Streptomycin sulfate
• Tobramycin sulfate.


Penicillins remain one of the most important and useful antibacterial drugs, despite the availability of numerous others. The penicillins can be divided into four groups:
• natural penicillins (penicillin G benzathine, penicillin G potassium, penicillin G procaine, penicillin G sodium, penicillin V potassium)
• penicillinase-resistant penicillins (dicloxacillin sodium, cloxacillin sodium, nafcillin sodium)
• aminopenicillins (amoxicillin, ampicillin, amoxicillin– clavulanate potassium)
• extended-spectrum penicillins (carbenicillin indanyl sodium, ticarcillin disodium).


Many antibacterial drugs introduced for clinical use in recent years have been cephalosporins. Cephalosporins are grouped into generations according to their effectiveness against different organisms, their characteristics, and their development:

• First-generation cephalosporins include cefadroxil, cefazolin sodium, cephradine, and cephalexin hydrochloride monohydrate. (See First-generation cephalosporins: Cefazolin.)
• Second-generation cephalosporins include cefaclor, cefotetan, loracarbef, cefprozil, cefoxitin, cefuroxime axetil, and cefuroxime sodium.
• Third-generation cephalosporins include cefdinir, ceftibuten, cefoperazone sodium, cefditoren, cefixime, cefotaxime sodium, cefpodoxime proxetil, ceftazidime, ceftizoxime sodium, and ceftriaxone sodium.
• Fourth-generation cephalosporins include cefepime hydrochloride.

Adverse reactions

Adverse reactions to cephalosporins include:
• confusion
• seizures
• bleeding
• nausea
• vomiting
• diarrhea.


Tetracyclines are broad-spectrum antibacterial drugs. They may be classified as:
• intermediate-acting compounds, such as demeclocycline hydrochloride and tetracycline hydrochloride
• long-acting compounds, such as doxycycline hyclate and minocycline hydrochloride.


Clindamycin is a derivative of another drug, lincomycin. Because of its high potential for causing serious adverse effects, clindamycin is prescribed only when there’s no therapeutic alternative. It’s used for various gram-positive and anaerobic organisms.


Macrolides are used to treat many common infections. They include erythromycin and its derivatives, such as:
• erythromycin estolate
• erythromycin ethylsuccinate
• erythromycin lactobionate
• erythromycin stearate.
Other macrolides include:
• azithromycin
• clarithromycin.


Vancomycin hydrochloride is used increasingly to treat methicillin-resistant S. aureus, which has become a major concern in the United States and other parts of the world. Because of the emergence of vancomycin-resistant enterococci, vancomycin must be used judiciously. As a rule of thumb, it should be used only when culture and sensitivity test results confirm the need for it.


Carbapenems are a class of beta-lactam antibacterials that includes:
• imipenem-cilastatin sodium (a combination drug)
• meropenem
• ertapenem
• doripenem.


Monobactams are used when a patient is allergic to penicillin. They bind and inhibit enzymes like other antibacterial drugs, but their composition is slightly different. Aztreonam is the first member in this class of antibacterial drugs and the only one currently available. It’s a synthetic monobactam with a narrow spectrum of activity that includes many gram-negative aerobic bacteria.


Fluoroquinolones are structurally similar synthetic antibacterial drugs. They’re primarily administered to treat UTIs, upper respiratory tract infections, pneumonia, and gonorrhea. Examples of fluoroquinolones include:
• ciprofloxacin
• levofloxacin
• moxifloxacin hydrochloride
• norfloxacin
• ofloxacin.


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