How many fluid ounces of the isotonic solution should be used to prepare 0.65 % ophthalmic drops

How many fluid ounces of the isotonic solution should be...

Key Concepts

Percentage Concentration

This concept refers to the proportion of the active pharmaceutical ingredient in a solution, typically expressed as a percent weight-by-volume (w/v). It determines how much of the drug is present per 100 mL of solution, which is crucial in preparing formulations with accurate dosing and efficacy.

Dilution Principle

The dilution principle involves reducing the concentration of a solution by mixing it with an appropriate quantity of solvent. In the context of this problem, it is used to calculate how much isotonic solution must be added to achieve the desired 0.65% concentration of timolol in the final ophthalmic drops.

Dimensional Analysis

Dimensional analysis is a systematic method used to convert units and ensure that the calculations for pharmaceutical compounding are consistent. It is particularly important when converting between units such as grams, milliliters, and fluid ounces, which is essential for accurate medication preparation.

Isotonic Solution

An isotonic solution is one that has the same osmotic pressure as bodily fluids, making it suitable for ophthalmic applications. Understanding its properties is important in formulation to avoid irritation or damage to the eye, ensuring that the final ophthalmic drops are safe and comfortable for use.

Transcript

00:01 Problem 46 reads, a nurse wants to add water to 30 ounces of a 10 % solution of benzalconium chloride to dilute it to an 8 % solution.

00:09 How much water must she add? hence, water is 0 % benzalconium chloride.

00:15 So to start off, i made a chart that has the solution, the water, the mix, and uses the equation amount, time strength is equal to the amount of chloride.

00:23 So we're going to start with the solution that is 30 ounces.

00:32 And is 10 % benzene chloride, so 10 % as a decimal 0 .10.

00:39 And then we want to figure out how much water needs to be mixed, and water is 0 % or 0 as a decimal strength of chloride.

00:51 And then the mix is going to be 30 plus x in terms of its amount, and the strength of it is going to be 0 .08.

01:03 So to find the amount of chloride in each, each liquid, we have to multiply the amount times of strength.

01:09 So for the solution, it's going to be three since 30 times 0 .10 is 3.

01:14 And then for water, it's going to be 0x or just 0.

01:19 And then for now, just write 0x, 0 times x.

01:23 And then for the mix, it's going to be 0 .08 times 30 plus x.

01:38 From here, we're going to add the amount of chloride in the solution and in the water and make it equal to the amount of chloride in the mix.

01:46 Our equation is going to be 3 plus 0x, which is just 0, is equal to 0 .08 times 30 plus x, then you're going to want to multiply or distribute the 0 .08 to the 30 into the x.

02:16 But before we're going to do that, we actually want to get rid of the decimal in 0 .08.

02:20 So we're going to multiply both sides of the equation by 100...

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