oral solution Flashcards
definition of pharmaceutical solutions
liquid preparations in which therapeutic agent and excipients are dissolved in liquid solvent system
aromatic waters
saturated aqueous solutions of volatile substances
elixirs
oral solutions containing alcohol
spirits
alcoholic or hydroalcoholic solutions of volatile substances, some are used as flavorings agents and some as medicines
advantages of oral solutions
fast and onset drug action
dose uniformity is assured
volume of liquid dose can be measured accurately to tailored dose
easy to swallow
easy to manufacture
disadvantages of oral solutions
less stable in solid dosage forms
colour change
precipitation
microbal growth
can be hard to dissolve in water
may have unpleasant taste or odour
packaging, transportation and storage costs are too high
why does drug concentration need to be below saturation
to avoid precipitating
why is water the most commonly used solvent
lack of toxicity
low cost
purified water is used as tap water could contain substances that interfere with drug formulation
purified water is produced by distillation, ion exchange or reverse osmosis
what is purified water used for
used for the preparation of medicines that do not have to be sterile
what is highly purified water used for
preperation of medicines where water of high biological quantity is needed, except water for injections
what is water for injections used for
used for medicines for paternal administration
must be pyrogen-free
what is steralized water for injections used for
medicines for paternal administration
water has been sterilised by heat and is suitably packaged
what are nonaqueous solvents
Used when the drug is insufficiently soluble or stable in aqueous systems, or when a
solution is intended for specific properties, such as sustained drug absorption.
viscosity enhancer (excipients)
improve pouring quality
preservatives (excpients)
prevent microbial growth
sweeteners (preservatives)
improve palatability of oral solutions
antioxidants (excipients)
improve stability of the solutions by minimizing oxidation
flavoring agents
mask unpleasant taste of drugs
what factors can affect the stability of a solution during its shelf life
interactions with container closure system such as
high temperature
pH
oxygen
UV light
catalysts
coloring agents
correlate with the flavouring agent
methods to enhance solution stability
formulate at a suitable pH
include excipients to enhance product stability
include antioxidants or metal chelators to reduce oxidation
package in containers that reduce light transmission
add nitrogen to create nitrogen headspace
what affects drug solubility and how can you increase solubility
molecular and crystal structure
solvent
pKa
PH of the medium
solubility can be increased by
pH modification
co-solvent
complexation
surfactant
look at henderson hassle bach equation
okay
how does altering pH increase drug solubility
altering pH can increase ionisation which increases drug solubility
what is a co-solvent system
a system where a water-miscible or partially miscible organic solvent is mixed with water to form a modified solution. this is called solvency
why are co solvents used
co solvents are used as many drugs are nit water soluble.
this allows them to dissolve such as ionic bonds since ‘like dissolves like’
what are cyclodextrins
a family of compounds made up of sugar molecules bound together in a ring
the 3 most important cyclodextrins are:
6- membered sugar ring
7- membered sugar ring
8- membered sugar ring
cyclodextrins complexation
they are in a hollow truncated cone shape
their effect is to increase aq solubility of drugs
when orally administered the drug is released and can absorbed by the body
regions of a surfactant and its function
the two regions are hydrophobic and hydrophilic regions
reduces the surface tension of liquids
self assembled to form micelles at the critical micelle concentration
considerations when switching between oral formulations of the same drug
administration times
bioavailability differences
excipients (allergy)
modified release formulation
site of action
