3 ml of LA solution contains 2% lignocaine with 1:100000 epinephrine how many milligrams of each are present in the solution?
## Core Concept
The question tests the understanding of local anesthetic (LA) solutions, specifically the calculation of the amount of active ingredients (lignocaine and epinephrine) present in a given volume. Lignocaine (lidocaine) is a commonly used local anesthetic, and epinephrine is often added to prolong the duration of action and reduce systemic toxicity.
## Why the Correct Answer is Right
To solve this, we need to understand the concentrations given:
- 2% lignocaine means 2 grams of lignocaine per 100 ml of solution.
- 1:100,000 epinephrine means 1 gram of epinephrine per 100,000 ml of solution.
Given 3 ml of solution:
- The amount of lignocaine = 2% of 3 ml = 2 g/100 ml * 3 ml = 0.06 g or 60 mg.
- The amount of epinephrine = 1 g/100,000 ml * 3 ml = 0.00003 g or 0.03 mg.
## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because it does not match our calculations for either lignocaine or epinephrine.
- **Option B:** This option is incorrect as it inaccurately represents the milligrams of lignocaine and epinephrine in the solution.
- **Option D:** This option is incorrect because it also does not align with the calculated amounts of lignocaine and epinephrine.
## Clinical Pearl / High-Yield Fact
A key point to remember is that when calculating drug concentrations, it's crucial to understand the units (e.g., percentage, ratio) and to be able to convert them into milligrams or micrograms per milliliter as needed. This skill is essential in clinical practice for accurately preparing and administering medications.
## Correct Answer Line
**Correct Answer: C.**