A doctor orders phenytoin 15 mg/kg loading dose p.o., then 300 mg/d. You have the following drug available.

a. How many mg of this anticonvulsant would you administer to a client who weighs 80 kg?

body weight = 80 kg, order = 15 mg/kg, dose = ?

$80\mathrm{ kg}\times \frac{15\mathrm{ mg}}{1\mathrm{ kg}}=1200\mathrm{ mg}$

The client should receive 1200 mg of phenytoin for the loading dose.

b. How many tablets would you administer?

$1200\mathrm{ mg}\times \frac{1\mathrm{ tablet}}{100\mathrm{ mg}}=12\mathrm{ tablets}$

The loading dose is equivalent to 12 tablets of phenytoin.

An order of Vibramycin (doxycycline calcium) 2 mg/lb q.d. p.o. for 10 days. Use the label to determine how many millilitres of this antibiotic you would administer to a client who weighs 90lb.

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client weight = 90 lb, order: 2 mg/lb, strength = 25 mg/5 mL

First, we need to calculate the dose based on the weight of the client and the order.

$90\mathrm{ lbs}\times \frac{2\mathrm{ mg}}{1\mathrm{ lb}}=12\mathrm{ mg}$

Every 5 mL of the solution contains 25 mg of the drug,

$180\mathrm{ mg}\times \frac{5\mathrm{ mL}}{25\mathrm{ mg}}=36\mathrm{ mL}$

The client should receive 36 mL of Vibramycin every day for 10 days.

The physician orders Biaxin (clarithromycin) 7.5 mg/kg p.o. q.12.h.. If the drug strength is 250 mg/5 mL, how many mL of this antibiotic drug should be administered to a client who weighs 154 pounds?

Since the weight of the client is given in pounds, but the order is in kilograms, we have to convert the client's weight into kilograms. Since $1\mathrm{ kg}=2.2\mathrm{ lbs}$

$154\mathrm{ lbs}\times \frac{1\mathrm{ kg}}{2.2\mathrm{ lbs}}=70\mathrm{ kg}$

Now, we find the dosage required for the order based on the size of the client.

$70\mathrm{ kg}\times \frac{7.5\mathrm{ mg}}{1\mathrm{ kg}}=525\mathrm{ mg}$

Finally, we convert into millilitres.

$525\mathrm{ mg}\times \frac{5\mathrm{ mL}}{250\mathrm{ mg}}=10.5\mathrm{ mL}$

The client should receive 10.5 mL of Biaxin by mouth every 12 hours.

A 3-year-old child weighing 30 lb is prescribed to receive vancomycin hydrochloride (Vancocin) 30 mg/kg/day q.i.d. How many milligrams of the medication will the nurse provide the child for each dose?

Converting the child's weight to kg:

$30\mathrm{ lbs}\times \frac{1\mathrm{ kg}}{2.2\mathrm{ lbs}}=13.63636\mathrm{ kg}$

The order states 30 mg/kg/day. We can find the mg per day now that we have the child's weight in kg.

$\frac{30\mathrm{ mg}}{1\mathrm{ kg}}\times 13.63636\mathrm{ kg}=409.0909\mathrm{ mg}$

Each day, the child receives 409.0909 mg of Vancocin. Q.i.d. represents four times a day, the final step is to find the mg in each dose.

$\frac{409.0909\mathrm{ mg}}{1\mathrm{ day}}\times \frac{1\mathrm{ day}}{4\mathrm{ dose}}=102.2727\mathrm{ mg}$

The child will receive 102.3 mg (rounded to nearest tenth of a mg) of Vancocin each dose.