Liquid Dosage Forms Flashcards
What are the two physical states of liquid dosage forms?
True solutions and dispersions
What dosage forms are considered dispersions?
Suspensions and emulsions
What is the definition of a solution?
Liquid preparation that contains one or more chemical substances dissolved in a suitable solvent or mixture of miscible solvents (drug is individual molecules surrounded by solvent molecules)
What are the two delivery modes of liquid dosages and how are they given?
Systemic (oral, injection, sometimes to other membranes like nasal or rectal) and local (direct application to skin, eye)
Are drugs in solution absorbed into the body quickly or slowly?
Quickly, because the drug is already in solution and ready to pass through a biological membrane
What are some advantages of liquids?
They are easy to swallow and easy to spread, easy to administer (except injection), easy to make dose adjustments, and they are rapidly absorbed
How do you adjust the dose of a solution?
Changing the volume of a solution adjusts the dose
What is a co-solvent’s role in a solution and how does it work?
Co-solvents are necessary to help dissolve poorly soluble drugs, and they work by modifying the dielectric constant so the solution dissolves the drug easier
Liquids that contain ethanol as a co-solvent are called…
elixirs
What are some common ingredients found in liquid dosage forms?
Water and co-solvents (if needed), sweeteners (oral doses), preservatives (multi-dose containers), buffers, flavors and colors
What are the two kinds of preservatives and what are their roles?
Antimicrobial (inhibits bacteria and mold) and chemical (prevents degradation of the product, especially because of oxygen)
What is the role of buffers in liquid doses?
Controls pH
What are the three solvent vehicles that are suitable for oral administration?
Simple, Syrup, Elixir
What is contained in a simple solvent?
Water and minimum ingredients (may contain buffers, preservatives)
What is contained in a syrup solvent?
Large amounts of sucrose, flavors, and sweeteners
What is contained in an elixir solvent?
Water and ethanol, as well as sweetener if oral
What are some disadvantages of solutions?
The shelf life of a solution is not as long as solid state products (drug degrades faster), they are not very portable (inconvenient to carry large volumes around), poor taste can lower compliance, most drugs not very soluble
What is the ideal volume for adults that a drug should be soluble enough to be administered in?
5-15 milliters
Which drugs, polar or nonpolar, tend to be poorly water soluble?
Non-polar
What are the three common co-solvents?
Ethanol, propylene glycol, glycerin
What is a disadvantage of using co-solvents?
They have pharmacologic activity and so can’t be used in very high concentrations
At high concentrations, what effects does glycerin have?
Strong GI discomfort (diarrhea), and also supports microbial growth
At high doses, what effect does propylene glycol have?
Can be cardiotoxic
What kind of water is never used in pharmacy products?
Drinking water
What is required of sterile water for injection?
That it be both sterile and pyrogen-free
What are pyrogens?
Organism by-products like cell membrane fragments and lipo-proteins
Which are the three sterile waters might contain preservatives?
Sterile water for inhalation, purified water (distilled water), sterile water for irrigation
What is the purpose of preservatives in sterile water for inhalation?
Large batches could be made at one time, or the pt could be inhaling the solution over a long period of time
What is the most common sterilization method?
Steam sterilization
What symptom do pyrogens cause?
Fever
Which solution, opthalmic or otic, must be sterile?
Opthalmic
Are ear, eye, and nasal solutions made to be absorbed into the bloodstream?
No, they are made to act locally
What are the three types of sterile solutions applied directly to the eye and what are they for?
Washes (get rid of debris), therapeutic effect on surfaces (cornea and conjunctiva), therapeutic effect on deeper structures (must pass through cornea)
Why is it important for therapeutic eye treatments not to irritate the eye?
Eye irritation promotes tearing and crying, which would wash the drug out of the eye
What is an aerosol solution?
A drug solution broken up into very small droplets
What size droplet is required for an aerosol solution to fully penetrate the lungs?
droplets 5 microns in diameter
When trying to deliver drug to the nasal cavity, where is the drug deposit goal area?
Turbinate regions (systemic seems to work best specifically at Superior Turbinate)