Posology : מינונים

4.2      Posology and method of administration

Posology
The dosage depends on the susceptibility of the pathogens, and the severity of the disease.
Adults

The usual dosage in adults is shown in the following table:

Type of infection                     Dose           Dosing interval          Total daily dose Mild infections (caused by           500 mg           every 8 hours                1.5 g Gram-positive pathogens )              1g            every 12 hours                 2g Uncomplicated urinary tract            1g            every 12 hours                 2g infections
Moderate to severe infections          1g            every 6 - 8 hours           3g–4g (caused by Gram-negative pathogens )
Life-threatening infections          1 g -1.5 g          every 6 hours               4g–6g 
In individual cases, doses of up to 12 g were administered.

In adult patients with renal insufficiency, the dosage regimen below should be followed: 
Creatinine clearance        Serum creatinine        Total daily dose            Dosing interval (ml/min/1.73 m²)             (mg/100 ml)
 55                     1.5                   usual dose               unchanged 35-54                    1.6-3.0                 usual dose             12-hour interval 11-34                    3.1-4.5            half the usual dose         12-hour interval  10                      4.6            quarter the usual dose       24-hour interval 
In patients undergoing haemodialysis, the dosage regimen depends on the conditions of dialysis.

For perioperative use to prevent infections, doses depend on the type and duration of surgery.
The doses below are recommended:
30 minutes to 1 hour prior to surgery an initial dose of 1 g to 2g is administered I.V. or I.M.
For longer surgeries (2 hours or more) another dose of 500 mg to 1 g is administered I.V. or I.M. intraoperatively. The dose level and the timing depend on the type and duration of surgery.
Postoperatively, 500 mg to 1 g are administered I.V. or I.M. at intervals of 6 to 8 hours for 24 hours.

If potential infections are likely to be very dangerous for the patient (e.g. after cardiac surgery or major orthopaedic surgery such as total joint replacement), it is advisable to continue postoperative dosing for 24 up to 48 hours.

Elderly patients
No dose adjustments are needed in elderly patients with normal renal function.

Paediatric population
A total daily dose of 25 - 50 mg/kg body weight divided in 3 - 4 single doses, is effective in most mild to moderate infections.
In severe infections, the total dose may be increased to the maximum recommended dose of 100 mg/kg body weight.

Dose instructions for infants, toddlers and children (indicative values) 
Body weight         25 mg/kg daily in 3 doses               25 mg/kg daily in 4 doses dosing intervals volume to be           dosing intervals volume to be of approx. 8       withdrawn at a       of approx. 6       withdrawn at a hours              concentration of     hours              concentration of 125 mg/ml                              125 mg/ml
4.5 kg             40 mg                0.35 ml             30 mg              0.25 ml
9.0 kg             75 mg                0.6 ml              55 mg              0.45 ml 13.5 kg            115 mg               0.9 ml              85 mg              0.7 ml 18.0 kg            150 mg               1.2 ml              115 mg             0.9 ml 22.5 kg            190 mg               1.5 ml              140 mg             1.1 ml

Body weight        50 mg/kg daily in 3 doses                50 mg/kg daily in 4 doses dosing intervals volume to be            dosing intervals volume to be withdrawn at a        of approx. 6       withdrawn at a of approx. 8       concentration of      hours              concentration of 225 mg/ml                                225 mg/ml hours

4.5 kg             75 mg                0.35 ml             55 mg              0.25 ml
9.0 kg             150 mg               0.7 ml              110 mg             0.5 ml 13.5 kg            225 mg               1.0 ml              170 mg             0.75 ml 18.0 kg            300 mg               1.35 ml             225 mg             1.0 ml 22.5 kg            375 mg               1.7 ml              285 mg             1.25 ml

Neonates: Safety of use in neonates has not been established (see section 4.4).

Children with renal insufficiency
Creatinine clearance          Dose of cefazolin (mg/kg)              Dosing interval (h) (ml/min/1.73 m2)
> 50                      7 (up to 500 mg/dose)                     6-8 25-50                                 7                               12

10-25                              7                               24 - 36 < 10                              7                               48 - 72 
Children undergoing haemodialysis are given 7 mg/kg body weight at the beginning of treatment. As cefazolin serum levels drop by 35% to 65% during dialysis, a dose of 3 to 4 mg/kg body weight is administered between dialysis sessions (dialysis interval = 72 hours).

Duration of treatment
The duration of treatment depends on the course of the disease. In keeping with the general principles of antibiotic therapy, cefazolin should be continued for at least 2 to 3 days after the fever has subsided or proof is obtained for the eradication of the pathogens.

Method of administration
The prepared solution is administered by deep intramuscular or intravenous injection.
See also section 6.6.
Intramuscular administration
For I.M. administration the medicine should be dissolved in 0.5% lidocaine solution.
Intramuscular doses (max. 1g) should be injected into a large muscle mass.
The I.M. administration should only be used for uncomplicated infections.
Reconstitute with 0.5% lidocaine solution according to the following dilution table: 
Vial size                             Volume of solvent
1g                                    4 ml

Intravenous administration
Solutions for I.V. injections are prepared by dissolving the powder in water for injection or 0.9% sodium chloride solution. Use at least 4 ml of the solvent for each gram of powder.


Direct intravenous injection
Up to a dose of 1 g cefazolin may be administered by slow I.V. injection (3-5 minutes) made directly into a vein or through the cannula.

Solutions of cefazolin in lidocaine must not be administered by the intravenous route.

For instructions on reconstitution of the medicinal product before administration, see section 6.6.