Mea A. Weinberg - The Dentist's Drug and Prescription Guide

Now, the correct dose to give to the pediatric patient must be calculated ( Table 3.3).

How is the prescription written ( Table 3.4)?

Dose required: <12 year: 15–30 mg/kg/d q6–8 h; max. 3 g/day × 7–10 days (this is an established dosage. There is a dose range, so it depends on the weight of the patient and severity of the infection).

How supplied: 250, 500 mg tabs.

Calculate the dose of amoxicillin suspension in mL for a 10‐year‐old child weighing 32 kg (70 lbs) ( Table 3.6).

Dose required: 25–45 mg/kg/day divided bid or 20–40 mg/kg/day q8h (this is given by the manufacturer). Table 3.5 How to calculate dose if the child can swallow tabletsStep 1 Convert pounds to kg:70 lb × 1 kg/2.2 lb = 31.8 kgStep 2 Calculate the dose in mg:31.8 kg × 15 mg/kg/day = 477 mg/dayStep 3 Divide the dose by the frequency:477 mg/day ÷ 3 (tid) = 159 mg/dose q8hThe total dose is 159 mg every 8 hours. Since the tablets only come in 250 and 500 mg, it is probably best to prescribe the oral suspension to be more precise. Table 3.6 Calculating the dose of amoxicillin suspension in mL for a 10‐year‐old child weighing 70 lbStep 1 Convert pounds to kg:70 lb × 1 kg/2.2 lb = 31.8 kgStep 2 Calculate the dose in mg:31.8 kg × 40 mg/kg/day = 1272 mg/dayStep 3 Divide the dose by the frequency:1272 mg/day ÷ 3 (tid) = 424 mg/dose bidStep 4 Convert the mg dose to mL:424 mg/dose ÷ 125 mg/5 mL = 3.39 mL bidStep 5 Convert mL into teaspoonfuls a 3.39 mL ÷ 5 mL = 0.68 teaspoonful Rx: amoxicillin oral suspension 125 mg/5 mLDisp: 100 mL bottleSig: Take 3.4 cc orally three times a day for 7 days for dental infectionNote: mL (milliliters) is sometimes referred to as cc or cubic centimeters. Usually, a medical dropper will have markers in cc which is the same as mL. There is probably less misinterpretation when mL is used rather than cc. a Each teaspoonful is 5 mL.

How supplied: suspension comes in concentrations of 125 mg/5 mL, 250 mg/5 mL, 250 mg/mL, 400 mg/mL (100 mL bottle).

Advise the parent to get a medicine dropper/spoon rather than using an ordinary teaspoon because of variations in measurements of a teaspoonful. After amoxicillin solution is mixed, it is best to store it in a refrigerator between 2 °C and 8 °C (36–46 °F); do not freeze. Throw away any unused medicine after 14 days.

Dose required: 25–45 mg/kg/day divided bid or 20–40 mg/kg/d q8h (this is given by the manufacturer).

How supplied: chewable tabs 125, 400 mg.

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

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

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

a Each teaspoonful is 5 mL.

Table 3.10 Pediatric dosage schedule

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

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

Dose required: 10 mg/kg/day q24h × 3 days.

How supplied: oral suspension comes in concentrations of 100 mg/5 mL, 200 mg/5 mL, 1 g powder packet.

1 Q. When should the 100 mg/5 mL suspension be prescribed?

2 A. The 100 mg/5 mL strength is prescribed for younger children weighing less than 44 lb (20 kg). Table 3.12 Calculating the dose of azithromycin oral suspension in mL for a 10‐year‐old child weighing 70 lb and how the prescription should be writtenStep 1 Convert pounds to kg:70 lb × 1 kg/2.2 lb = 31.8 kgStep 2 Calculate the dose in mg:31.8 kg × 10 mg/kg/day = 318 mg/dayStep 3 Divide the dose by the frequency:318 mg/day once a day = 318 mg/doseStep 4 Convert the mg dose to mL:318 mg/dose ÷ 200 mg/5 mL = 7.9 mL q24h Rx: azithromycin oral suspension 200 mg/5 mLDisp: 1 bottle (100 mL)Sig: Take 7.9 mL orally once a day for 3 days for dental infection Table 3.13 Calculating the dose of azithromycin tablets in mg for a 10‐year‐old child weighing 70 lbStep 1 Convert pounds to kg:70 lb × 1 kg/2.2 lb = 31.8 kgStep 2 Calculate the dose in mg:31.8 kg × 10 mg/kg/day = 318 mg/dayStep 3 Divide the dose by the frequency:318 mg/day once a day = 318 mg/dose once a dayThe strengths of tablets are 250, 500, or 600 mg. Since the dose is 318 mg once a day, it is probably more precise to prescribe the oral suspension. Table 3.14 Calculating the dose of clindamycin oral solution in mL for a 10‐year‐old child weighing 70 lb and how the prescription should be writtenStep 1 Convert pounds to kg:70 lb × 1 kg/2.2 lb = 31.8 kgStep 2 Calculate the dose in mg:31.8 kg × 10 mg/kg/day = 318 mg/dayStep 3 Divide the dose by the frequency:318 mg/day ÷ 3 (tid) = 106 mg/dose q8hStep 4 Convert the mg dose to mL:106 mg/dose ÷ 75 mg/5 mL = 7 mL tidStep 5 Convert mL into teaspoonfuls a 7 mL ÷ 5 mL = 1.4 teaspoonful Rx: Clindamycin oral solution 75 mg/5 mLDisp: 1 bottleSig: Take 1.4 teaspoonful orally three times a day for 7 days for dental infection a Each teaspoonful is 5 mL.