Drug Research: Cefazolin (Cephazolin; Ancef, Kefzol)

Drug Research: Cefazolin (Cephazolin; Ancef, Kefzol)
Name
Institution
Patient Case Scenario 1
Mr. y is a 78 year old retired teacher with type 1 diabetes. He has managed this condition for close to two years and he runs a butchery business which he started after his retirement. He lives with his wife who is in her mid sixty. He was brought to hospital suffering from pneumonia. His condition can be treated with cefazolin antibiotic which is very effective in treating most of the illnesses caused by gram –positive and some gram negative bacteria. Care should be taken to avoid or minimize adverse effects or even drug interaction because of the drugs he uses to manage his diabetic condition.
Case scenario 2
Mrs. W is a young woman who is 26 years old. She is a mother of one child who is 3 years old. She lives with her husband who is tender and caring as well as the sole bread winner of the family. She came into the hospital with complains of the lower abdominal ache and back ache. On examination, the lab tests indicated that she had severe urinary tract infection caused by susceptible bacterial organisms. She was prescribed cefazolin antibiotic to treat her condition. Care should be taken to avoid drug interaction because she is on family planning pills. She should be advised accordingly to ensure that she understands how the drug works and the possible adverse effects and how to manage them.
Mechanism of Action and Therapeutic Effects
Cefazolin just like other drugs in the class of Cephalosporins exert their bactericidal action by inhibiting the later stages of bacterial cell wall formation. Specifically cefazolin inactivates one or several penicillin-binding proteins as well as blocking cross-linking of peptidoglycan structure. In addition, cephalosporins are thought to be involved in activation of bacterial cell autolysins which are likely to cause bacterial cell wall lysis (Lilley et al, 2010).
Therapeutic Uses
The therapeutic classification of cefazolin is a First-Generation –Cephalosporin and is an antibiotic that is effective against a large spectrum of antimicrobial. It is effective against Gram-positive bacteria such as MSSA (methicillin –susceptible Staphylococcus aureus), coagulase negative Staphylococci, Streptococci species, penicillin-susceptible Streptococcus pneumonia and also Gram negative bacteria such as Maraxella catarrhalis , Klebsiella pneumoniae, Escherichia coli and Proteus mirabilis (Lilley et al, 2010). The drugs classified in first class generation cephalosporin are prescribed to treat various conditions such as septicemia, pneumonia, bone and joint infections, bacteria endocarditis, otitis media, soft tissue and skin infections, urinary tract infections caused by susceptible bacterial organisms and burn wound infections. Cefazolin is the preferred drug for use in perioperative prophylaxis because it has a longer half-life (Mazuski, 2009).
Pharmacokinetic including Aspects of Absorption, Distribution, Metabolism, and Excretion of the Drug
Cefalozin is administered either through intramuscular or intravenous routes. It well absorbed and is excreted untransformed in the urine primarily through glomerular filtration and to a lesser level through tubular secretion. After 500mg of cefazolin is administered intramuscularly, 56% to 89% of it is recovered within a period of 6 hours while roughly 80% to 100% is recovered within a period of 24 hours. Following intramuscular administration of 500g and 1g of cefazolin dose, the peak urine concentration above 1000mcg/Ml and 4000mcg/mL is achieved respectively. The mean serum levels in patients undergoing peritoneal dialysis at 2L/hr is roughly 10 and 30 mcg/mL after 24 hours’ instillation of a dialysing solution that contains 50mcg/mL and 150mcg/mL respectively. Intra-peritoneal administration of this drug is typically well tolerated (Lilley et al, 2010).
Cefazolin readily infiltrates an inflamed synovial membrane reaching a concentration ion the joint space that is comparable to levels in the serum. The drug also crosses the placental barrier entering the amniotic fluid and the cord blood. It is therefore not recommended to prescribe the drug during pregnancy. However, Cefazolin concentration in milk of breastfeeding mothers is very low and the drug can therefore be prescribed to the nursing mothers (Lilley et al, 2010).
Table 1 Serum Concentrations after Intramuscular Administration (Average of two studies)
Dose / Serum Concentrations (mcg/mL)

½ hr

1 hr

2hr

4hr

6hr

8hr

250 mg

15.5

17

13

5.1

2.5

-

500mg

36.2

36.8

37.9

15.5

6.3

3

1g

60.1

63.8

54.3

29.3

13.2

7.1

Clinical pharmacology studies shows that cefazolin when administered to patients who have infections produces similar mean peak serum levels that are nearly equivalent to the levels observed in normal volunteers (AFTP, 2011).
Table 2. Serum Concentration after 1g Intravenous Dose
5 min

15 min

30 min

1hr

2hr

4hr

188.4

135.8

106.8

73.7

45.6

16.5

Adult and Paediatric Dosages and Modes of Administration
Cefazolin-AFT is either administered intravenously or intramuscularly after it has been reconstituted. The total daily dosage for either mode of administration is the same. Cefazolin-AFT should not be administered through intrathecal route of administration because it has been reported that it causes severe CNS toxicity including seizures (Lilley et al, 2010; Mazuski, 2009).
Intramuscular Administration:
The 500mg vial can be reconstituted with sterile water for injection, sodium chloride injection or bacteriostatic water for injection. However, the 1g vial is reconstituted with either bacteriostatic water for injection or sterile water for injection only. Cefazolin-AFT should only be injected into large muscle. Reconstitution should be as directed in the table below (Lilley et al, 2010).
Table 3 Dilution Table
Vial size

Diluent to be added

Approx. available volume

Approx. average concentration

500mg

2mL

2.2 mL

225mg/mL

1g

2.5 mL

3mL

330mg/mL

Intravenous Injection
The diluted solution is administered either through tubing or into the vein. The reconstituted 1g or 500mg of Cefazolin –AFT is diluted in a minimum of 10 mL sterile water for injection. The solution should be injected slowly over duration of 3 to 5 minutes (AFTP, 2011).
Adult Dosage
Type of infection

Dose

Frequency

Mild infections resulting from susceptible Gram-positive cocci

250gm- 500g

8hrs

Acute uncomplicated urinary tract infections

1g

12 hourly

Infections that are moderate to severe
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