# How many milliliters are in 10 milligrams

concentrationPharmaWiki The concentration (C) is an indication of the content. For example, it indicates the mass of a substance that is dissolved in a certain volume. In pharmacy, concentrations are mainly used for liquid and semi-solid dosage forms.

synonymous: C

definition

A concentration (C) indicates the content of one substance in another as a quotient. By definition, this means the amount of a substance that is present in a certain volume. However, concentrations can also relate to masses.

In pharmacy, the concentration is often used in connection with liquid and semi-solid dosage forms. In the case of solid medicinal forms such as tablets or capsules, it is more common to indicate the mass of the active ingredients.

Mass concentration

For example, an oral oxycodone solution contains 10 milligrams (mg) of anhydrous oxycodone hydrochloride per milliliter (ml): 10 mg / ml.

This example is the so-called mass concentration with the unit gram per liter (g / L, i.e. m / V).

A physiological saline solution contains 9 g of sodium chloride (mass) per 1 liter of water (volume). Their concentration is usually given as a percentage: 0.9%. It is 9 g / L or 9 mg / ml. For the preparation, 9 g of sodium chloride are weighed out and made up to 1000 ml (not grams!). For example, a measuring cylinder can be used to determine the volume (see under Glassware in Chemistry).

Production of a sodium chloride solution 0.9%, click to enlarge. Illustration © PharmaWiki

Mass percentage

Two masses can also be related to one another. For example, 100 g of a diclofenac gel contain 1 g of diclofenac sodium. The concentration is 1% or 10 mg / g (m / m).

If such a gel is prepared, there is no need to work with volume. The gel consists of 1 g of active ingredient and 99 g of base. The components can be weighed with a scale. Note the difference from the example above.

Volume concentration

In the case of volume concentration, two volumes are related to one another. The unit is L / L. The percentages of ethanol often relate to volume.

100 ml of ethanol 20% (V / V) means that this preparation contains 20 ml of pure (anhydrous) alcohol.

Caution: Volumes with different densities cannot be added! See under → Dilutions.

Amount of substance concentration

In the case of the molar concentration (molarity), the amount of the substance is specified in the amount of substance (mol), i.e. the number of particles contained. The unit is mol per liter (mol / L), officially according to SI: mol / m3.

A 1 molar solution contains 1 mol of the substance in 1 liter of water. This is also known as a 1M.

One → mole of a substance corresponds to 6.022 140 76 × 1023 Particle (= Avogadro number).

Active ingredient salts

Active ingredients are contained in many medicinal products in the form of → salts (→ active ingredient salts). Since these have a different (higher) molecular weight than the active ingredient, the concentrations differ in relation to the active ingredient and its salt. In the above example with oxycodone, the concentration of the pure oxycodone base is only 9 mg / ml instead of 10 mg / ml (salt). This can play a role in the dosage. See also → active ingredient salts.

Changes in concentration

If the contained substance or the volume is changed, for example increased or reduced, the concentration changes. For example, if there is 1 g of sodium chloride in 1000 ml of water, the concentration is 1 g / L. If you make up to 2 liters with water, the concentration is only 0.5 g / L.

The following formula, the so-called mixing cross, is used for calculations in connection with dilutions:

• C1 (concentration 1) x V1 (volume 1) = C2 (concentration 2) x V2 (volume 2)

C: percent or molar concentration

You can find detailed information in the article → Dilutions

Calculate with concentrations

Example:

An ibuprofen suspension contains 20 mg / ml ibuprofen. You want to give a five-year-old child a single dose of 100 mg ibuprofen for a fever. How much suspension do you need?

Solution: 5 ml

Plasma concentration, mass, volume, amount of substance, density, dilutions

literature
• European Pharmacopoeia PhEur
• Specialist literature
• Chemistry textbooks
• Pharmaceutical Technology Textbooks
author

Conflicts of Interest: None / Independent. The author has no relationships with the manufacturers and is not involved in the sale of the products mentioned.

Support PharmaWiki with a donation!

© PharmaWiki 2007-2021 - PharmaWiki provides independent and reliable information about medication and health.