McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 9  Antibiotics

TABLE 9.5

DRUGS IN FOCUS Penicillins and penicillinase-resistant antibiotics

Drug name

Dosage/route

Usual indications

Penicillins benzathine penicillin (Bicillin)

675 mg–1.8 g IM

Mild to moderate URTI, streptococcal infections, syphilis, rheumatic fever Treatment of infections caused by sensitive organisms; treatment of syphilis, prevention of bacterial endocarditis, wound infection and sepsis Severe staphylococcal and other gram-positive coccal infections; skin and wound infections, pneumonia, osteomyelitis Treatment of staphylococcal or other gram- positive coccal infection; pneumonia, osteomyelitis skin and wound infection Treatment of mild to moderate infections due to sensitive organisms

benzylpenicillin (BenPen)

Adult and paediatric >10 years: 300 mg IM or IV q 6 hours Paediatric 3–10 years: 150–300 mg IM or IV q 6 hours Paediatric: <3 years: 60 mg IM or IV q 6 hours Adult: 250–500 mg IV or 250 mg PO q 6 hours Paediatric: 25–50 mg/kg/day IV q 6 hours

dicloxacillin (Diclocil, Distaph)

flucloxacillin (Flopen, Staphylex)

Adult: 250 mg PO of IV q 6 hours

phenoxymethylpenicillin benzathine (Abbocillin, Cilicaine V ) phenoxymethylpenicillin potassium (Abbocillin VK, Cilicaine VK)

Adult: 250–500 mg PO q 4–6 hours Paediatric: 15–50 mg/kg/day in 3–6 divided doses

Adult: 250–500 mg PO q 4–6 hours

Treatment of mild to moderate infections due to sensitive organisms

procaine penicillin (Cilicaine)

Adult: 1.5 g/day IM for 2–5 days

Moderately severe infections due to organisms sensitive to penicillin

Broad-spectrum penicillins amoxycillin (Amoxil, Augmentin, Cilamox)

Adult: 250–500 mg PO q 8 hours Paediatric: 20 mg/kg/day PO in divided doses q 8 hours Adult: 250–500 mg IM or IV q 6 hours, then 500 mg PO q 6 hours when oral use is feasible Paediatric: 60 mg/kg/day IM or IV in 4–6 divided doses, then 250 mg PO q 6 hours Adult and paediatric >12 years: 4 g IV q 8 hours Paediatric <12 years: 100 mg/kg IV q 8 hours

Broad spectrum of uses for adults and children

ampicillin (Amicyn, Ibimicyn)

Broad spectrum of activity; useful form if switch from parenteral to oral is anticipated; monitor for nephritis

piperacillin (Tazocin, Tazopip)

Treatment of serious bacterial infections caused by sensitive organisms; lower respiratory tract infection, skin and intra-abdominal infection, bacterial septicaemia, gynaecological infection Severe infections caused by susceptible bacteria

ticarcillin (Timentin)

Adult: 1 g IM or direct IV q 6 hours; reduce dose with renal impairment Paediatric: 50–100 mg/kg/day IM or direct IV q 6–8 hours

of the cell wall, and the bacteria with weakened cell walls swell and then burst from osmotic pressure within the cell. Because human cells do not use the biochemical process that the bacteria use to form the cell wall, this effect is a selective toxicity. The penicillins are indicated for the treatment of streptococcal infections, including pharyngitis, ton- sillitis, scarlet fever and endocarditis; pneumococcal infections; staphylococcal infections; fusospirochetal infections; rat-bite fever; diphtheria; anthrax; syphilis;

and uncomplicated gonococcal infections. At high doses, these drugs are also used to treat meningococcal meningitis. See Table 9.5 for usual indications for each agent. Pharmacokinetics Most of the penicillins are rapidly absorbed from the GI tract, reaching peak levels in 1 hour. They are sensi- tive to the gastric acid levels in the stomach and should