Exam 3 Flashcards
(73 cards)
liquid dosage forms that only contain one phase
monophasic
liquid dosage forms that have dispersion
biphasic
coarse vs colloidal
types of dispersions
classification of liquid dosage forms - ready to use liquids
solutions, suspensions, emulsions
classification of liquid dosage forms - powders for reconstitution
chemically unstable drugs, solution or suspension, oral, topical, injectable
injectable, ophthalmic, some nebulized liquids, vehicles (SW, NS, etc.)
sterile liquid dosage forms
we must ensure a low bioburden by proper procedures during manufacture, storage, distribution, dispensing (classification of liquid dosage forms)
non-sterile
easier to swallow than solids (pediatric, geriatric, dysphagia), faster absorption rate, easier to adjust the dose (can be diluted, compounded), liquids are best dosage form for some routes (IV) or for some drugs
advantages of liquid dosage forms
increased chemical instability, prone to microbial contamination, inconvenient and bulky, taste issues, less accurate dosing, leakage/loss, too rapid absorption, controlled release difficult to achieve
limitations of liquid dosage forms
solvents/cosolvents, solubilizers, preservatives, sweeteners, surfactants, suspending agents, antioxidants, flavoring agents, buffering agents
excipients for liquid dosage forms
to inhibit the growth of microorganisms that might be introduced from repeatedly drawing doses (sterile), to protect from microbiological growth (non-sterile)
why preserve a product
activity against various microorganisms, safety, pKa of preservative, pH of product, solubility of preservative, stability of preservative, suppliers/cost/regulatory limits
preservative considerations
physiologically compatible, maintain stability, improve solubility
pH of liquids
routes of administration, volume of product (small vs large), way of administration (infusion or bolus injection), buffered or unbuffered, occasional dosing or repeated use
acceptable pH ranges depends on these things
pH of formulation, presence of micelles, presence of hydrophilic polymers
factors affecting preservative efficacy in solutions
_________ is a preservative that is affected by the pH of the formulation
benzoic acid because it is ionized acid
if the pH is higher than the pKa more of the acid will be in the ionized form thus potentially rendering the preservative ineffective, when the preservative is ionized it is soluble in water so it won’t have antimicrobial activity because it essentially just goes away, need to have some unionized preservative to be effective, benzoic acid only effective at pH lower than 4
preservative-pH relationship
something surrounded by phospholipids
micelles
free concentration of preservative in solution is reduced in the presence of hydrophilic polymers due to chemical interaction, preservative may be incompatible with hydrophilic polymers in formulation due to electrostatic interaction (cationic hydrophilic polymers should not be used in conjunction with acidic preservatives)
presence of hydrophilic polymers
faster onset of activity (no rate limiting dissolution process), good for children and elderly (easy to swallow), homogenous/always uniform unlike suspensions and emulsions, flexible dosing (dose titration), given by many routes of administration (including IV infusion)
advantages of solutions
expensive to ship and bulky for patient to carry, leakage from container, unsuitable for therapeutic agents that are chemically unstable in the presence of water (less stability that solids), poor solubility of certain therapeutic agents may prohibit their formulation as solutions, more pronounced taste
disadvantages of solutions
oral, topical (dermal, ophthalmic, nasal, otic, inhalants, enemas/douches), parenteral
types of solutions
homogenous mixtures of solutes dissolved in solvents
solutions
aqueous solutions containing a high concentration of sugar or sugar substitute with or without medicinal substances
syrups
