Читать книгу The Dentist's Drug and Prescription Guide - Mea A. Weinberg - Страница 24

 Dose required: 25–45 mg/kg/day divided bid (given by the manufacturer).

 How supplied: capsules 250, 500 mg.

Table 3.7 Calculating the dose of amoxicillin chewable tablets in mg for a 10‐year‐old child weighing 70 lb

Step 1 Convert pounds to kg:	70 lb × 1 kg/2.2 lb = 31.8 kg
Step 2 Calculate the dose in mg:	31.8 kg × 30 mg/kg/day = 954 mg/day
Step 3 Divide the dose by the frequency:	954 mg/day ÷ 3 (tid) = 378 mg/dose bid

Since chewable tablets only come in strengths of 125 and 400 mg, it is recommended to always use the lower dose and then increase the number of days of therapy or to use the suspension instead, which may be more precise.

Table 3.8 Calculating the dose of amoxicillin capsules in mg for a 10‐year‐old child weighing 70 lb

Step 1 Convert pounds to kg:	70 lb × 1 kg/2.2 lb = 31.8 kg
Step 2 Calculate the dose in mg:	31.8 kg × mg/kg/day = 1272 mg/day
Step 3 Divide the dose by the frequency:	1272 mg/day ÷ 2 (bid) = 636 mg/dose bid

The dose is 636 mg bid; either 500 mg capsules can be prescribed and increase the number of days of therapy or it may be best to use the oral suspension.

1 Q. If the child in Case 1 (above) were allergic to penicillin, what other antibiotics could be prescribed?

2 A. Clarithromycin (Biaxin®) (Table 3.9)

 Dose required: 15 mg/kg/day divided q12h (Table 3.10).

 How supplied: oral suspension comes in concentrations of 125 mg/5 mL, 250 mg/5 mL (100 mL bottle) (Table 3.11).

Table 3.9 Calculating the dose of clarithromycin (Biaxin) in mL for a 10‐year‐old child weighing 70 lb

Step 1 Convert pounds to kg:	70 lb × 1 kg/2.2 lb = 31.8 kg
Step 2 Calculate the dose in mg:	31.8 kg × 15 mg/kg/day = 477 mg/day
Step 3 Divide the dose by the frequency:	477 mg/day ÷ 2 (bid) = 238.5 mg/dose bid
Step 4 Convert the mg dose to mL:	238.5 mg/dose ÷ 250 mg/5 mL = 4.77 mL q12h
Step 5 Convert mL into teaspoonfulsa	4.77 mL ÷ 5 mL = 0.954 teaspoonful bid

^a Each teaspoonful is 5 mL.

Table 3.10 Pediatric dosage schedule

Source: Adapted from www.rxlist.com/biaxin‐drug.htm

Weight (kg)	Weight (lb)	Dosage (q12h) (tablets)	125 mg/5 mLa (suspension)	250 mg/5 mL (suspension)
9	20	67.5 mg q12h	2.7 mL q12h	1.35 mL q12h
18	40	136 mg q12h	5.4 mL q12h	2.7 mL q12h
25	55	187.5 mg q12h	7.5 mL q12h	3.75 mL q12h
34	75	255 mg q12h	10 mL q12h	5 mL q12h

^a A teaspoonful is 5 mL.

This is an easy‐to‐follow table for prescribing clarithromycin to pediatric patients; the usual recommended dosage is 15 mg/kg/day divided q12h for 10 days.

Table 3.11 How the clarithromycin (Biaxin) prescription should be written

Rx: clarithromycin oral suspension 250 mg/5 mL

Disp: 1 bottle (100 mL)

Sig: Take 1 teaspoonful orally twice a day for 7 days for dental infection