simple liquid dosage forms HW reading

what is solution in physicochemical terms?

molecular dispersion of two or more substances (solid, liquid, gas)

what is solution in pharmaceutical terms?

liquid preparations that contain one or more substances dissolved in a suitable solvent or mixture of miscible solvents

what is solubility?

a measure of the maximum amount of a substance that will dissolve in a liquid (at a constant temperature)

what is a saturated solution?

a solution prepared at the maximum solute concentration at a given temperature

relative terms of solubility

percent weight in volume

% w/v

grams of constituent in 100 mL of preparation

(e.g., 1% w/v = 1 g constituent in 100 mL preparation)

percent volume in volume

% v/v

milliliters of constituent in 100 mL of preparation

(e.g., 1% v/v 1 mL constituent in 100 mL preparation)

percent weight in weight

% w/w

grams of constituent in 100 g of preparation

(e.g., 1% w/w = 1 g constituent in 100 g preparation)

ratio strength: weight in volume

—:— w/v

grams of constituent in stated milliliters of preparation

(e.g., 1:1000 w/v = 1 g constituent in 1000 mL preparation)

ratio strength: volume in volume

—:— v/v

milliliters of constituent in milliliters of preparation

(e.g., 1:1000 v/v = 1 mL constituent in 1000 mL preparation)

ratio strength: weight in weight

—:— w/w

grams of constituent in stated number of grams of preparation

(e.g., 1:1000 w/w = 1 g constituent in 1000 g preparation)

what is the proper administration of oral liquid dosage forms?

taken with water

measured by calibrated cups of spoons especially for potent medication

what are the solvents for pharmaceutical use?

• purified water, USP

• alcohol, USP

• diluted alcohol, NF

• rubbing alcohol

• isopropyl rubbing alcohol

• glycerin, USP

what is purified water, USP?

• common tap water contains up to 0.1% (w/v) solids

• tap water is ONLY used in cleaning, extracting, and some external use products

• purified water, USP - solid content is less than 0.001% (w/v)

• preparation: distillation, ion exchange, or reverse osmosis

• used for aq dosage forms (except parenterals)

PARENTERALS

1. water for injection, USP (not sterile by pyrogen free)

2. sterile water for injection, USP

3. bacteriostatic water for injection, USP

what is alcohol, USP?

• alcohol USP: 94.9 - 96% (v/v) ethyl alcohol

• dehydrated alcohol, USP, no less than 99.5% (v/v)

• used as solvent or co-solvent, good water miscibility, good dissolution power, antimicrobial properties

• alcohol and water mixtures are called hydroalcoholic solutions

• undesired pharmacological and potential effects of alcohol

FDA LIMITS OF ALCOHOL USE IN OTC PRODUCTS

for under the age of 6 years

less than or equal to 0.5%

FDA LIMITS OF ALCOHOL USE IN OTC PRODUCTS

for 6-12 years

less than or equal to 5%

FDA LIMITS OF ALCOHOL USE IN OTC PRODUCTS

for more than 12 years

less than or equal to 10%

what is diluted alcohol, NF?

• 50% alcohol USP in 50% purified water, USP

• actual strength is slightly higher because of 3% decrease in volume upon mixing

• used for pharmaceutical preparations and processes

what is rubbing alcohol?

• 70% ethyl alcohol by volume and the rest is water and denaturants

• contains bitter substances and organic additives that cannot easily be separated

• rubefacient, soothing rub, germicide for instruments, skin clearing

• also used as a vehicle for topical preparations

what is isopropyl rubbing alcohol (IPA)?

• 70% (v/v) IPA in water with or without colors, stabilizers and perfume oils

• used as a rubefacient externally and as a soothing rub

• vehicle for topical preparations

• for disinfecting skin before injection

• less likely to be abused than ethanol & denaturation is not necessary

what is glycerin, USP?

• clear syrupy liquid with sweet taste

• miscible with both water and alcohol

• comparable to alcohol in dissolution power

• can be used to reduce alcoholic content of preparations

• stabilizer - some preservative qualities

• viscous - drug dissolves slowly

• it is used in many internal preparations

other kinds of solutions

what are aromatic waters?

• clear aq solutions saturated with volatile oils or another aromatic or volatile substance

• orange flower oil, peppermint oil, rose oil, camphor

• uses: perfuming or flavoring agent

• no longer in widespread use for drug delivery/administration

other kinds of solutions

what are spirits?

• alcoholic or hydroalcoholic solutions of volatile substances

• usually >60% alcohol

• forms milky solution when mixed with water

• used as flavoring agent, or for the therapeutic value of the oil

• used orally, externally or by inhalation

• prepared by simple solution, maceration or distillation

• official USP spirits are:

  • camphor spirit, compound orange spirit, peppermint spirit

non-aq solutions

what are liniments?

• alcoholic, oleaginous solutions or emulsion of medications intended to be rubbed on the skin (but not on broken skin)

vehicle choice:

1. based on the use: rubefacient, counterirritant or massage

2. based on the solubility of active ingredients

• commonly used in oils: sesame, cottonseed, turpentine

• must indicate clearly not to be taken orally

• should be stored in tight containers

non-aq solutions

what are collodions?

• clear liquid preparation composed of Pyroxylin dissolved in a solvent mixture, with or without added medication

• pyroxylin - soluble gun cotton/collodion cotton, precipitates from the solution upon addition of water

• when applied to the skin with a fine camel’s hair brush, the solvent rapidly evaporates, leaving a filmy residue of pyroxylin

• provides occlusive protective coating on the skin

• uncomfortable due to a lack of flexibility

• intended for external use only