An ibuprofen suspension for infants contains 100 mg per 5.0 ml. The recommended dose is 10 mg per kilogram of body weight. How many milliliters of this suspension should be given to an infant weighing 12 lbs? (Assume 2 significant figures.)

First, we need to convert the infant's weight from pounds to kilograms since the recommended dosage is given in mg per kg of bodyweight. There are 2.20462 pounds in a kilogram.

$$ 12 \text{ lbs} \times \frac{1 \text{ kg}}{2.20462 \text{ lbs}} \approx 5.44 \text{ kg} $$

(rounded to 2 significant figures it is 5.4 kg since we're asked to use 2 significant figures.)

Now, we calculate the recommended dose for the infant as follows: $$ 5.4 \text{ kg} \times 10 \text{ mg/kg} = 54 \text{ mg} $$

The concentration of the ibuprofen suspension is 100 mg per 5.0 ml. To determine how much to administer for the 54 mg dose, use a proportion:

Given: 100 mg : 5.0 ml = 54 mg : X ml

Solving for X, we can set up the proportion as follows:

$$ \frac{100 \text{ mg}}{5.0 \text{ ml}} = \frac{54 \text{ mg}}{X \text{ ml}} $$

Cross multiply to solve for X:

$$ 100 \text{ mg} \cdot X \text{ ml} = 54 \text{ mg} \cdot 5.0 \text{ ml} $$

$$ X = \frac{54 \text{ mg} \cdot 5.0 \text{ ml}}{100 \text{ mg}} $$

$$ X = \frac{270}{100} $$

$$ X = 2.7 \text{ ml} $$

The infant should be given 2.7 ml of the ibuprofen suspension.

Extra: When it comes to medicine dosages, it's important to have an accurate measurement of weight to calculate the dose correctly. In this case, the weight needs to be converted from pounds to kilograms because the dosage of ibuprofen is prescribed in milligrams per kilogram. Dosages for children's medications are often provided this way because it allows the dose to be accurately adjusted based on the child's weight, leading to a more personalized and accurate dosage. Too little might not be effective and too much could be dangerous.

Ibuprofen is a common nonsteroidal anti-inflammatory drug (NSAID) often used to reduce fever and treat pain or inflammation. It's important to follow the dosing instructions provided by the healthcare provider or the manufacturer and to use the appropriate measuring device, such as a dosing syringe or cup, to measure liquid medicine.