medicinal solutions + medicinal suspensions

what is a solution

a mixture of two or more components that form a single phase that is homogenous down to the molecular level

what does a solute (disperse phase) do

its dissolved in the solvent

what does a solvent (dispesion medium) do

dissolves solute

what can a solute and a solvent be

a solid liquid and a gas

what is a true solution

it has one phase, its homogenous, it does not separate on standing and has molecular level mixing

what is a solution

a solid dissolved in a solvent which is homogenous at molecular level

what is a syrup

an aqueous solution containing a sugar solution for flavoring or preservation

what is an elixer

sweetened hydroalcoholic (combinations of water and ethanol) solutions.

what is a spirit

hydroalcoholic solutions of aromatic materials.

what is a tincture

alcoholic or hydroalcoholic solutions of chemical or soluble constituents of vegetable drugs.

what is an advantage of a solution

the drug is distributed evenly throughout liquid. accurate dosinf providing the volume is measure accurately. there is no dissolution step which means faster absorption and it is easy to swallow.

what are disadvantages of solutions

it is less stable and unpleasant flavours are hard to mask. its bulky to carry and you need a spoon or pippete to measure the oral dose.

what is a reason for high concentration of sucrose

high concentration is necessary for stability. the high osmotic pressure is to prevent microbial growth. That is more likely to happen if diluted below 66.7%. there is an increased viscosity or sweet taste to mask bitter drugs. mic

what are some pharmaceutical solutions examples

eye drops, ear drops and enemas

what flow is exhibited by syrup bp

newtonian

what do you use if sugar bp was subsriured with a sugar free solution and you had to alter the rheological properties.

you must use a viscosity enhancer. they can be natural semi synthetic and synthetic.

example of a natural viscosity enhancer

cellulose, starch, xanthan, carageenan, hydaluronan

example of semisynthetic viscosity enhancers

cellulose esters like amc,hec,ec,cmc

example of synthetic viscosity enhancers

PAA,PVP,PEG and PEO

why do we increase viscosity

to improve retention time, reduce sedimentation, improve patient acceptability and control flow behaviour

what does polyacrilic acid (PAA) do with ph and when its low or high

it changes its behaviour, with a low ph it means there is hydrogen bonding and cloudy dispersion. with a high ph ionisation occurs so polymer chains repel each other which produces clear hydrogel. ph dramatically changes polymer viscosity and appearance.

concering the stability of a pharmaceutical solution what are some key factors

it should have a shelf life of 3 years, potency should not fall below 99% and product should look and perform the same as itdid when manufactured.

how can drug content be measure accurately

using uv visible spectroscopy to determine the drug concentrationof each time point, validation of the results would be based on a calibration curve of absorbance as a function of drug conc.

what is a pharmaceutical suspension

the dispersion of fine insoluble solid particles (disperse phase) within a liquid. components include a disperse phase which are solid drug particles and a continuous phase that is the liquid vehicle.

what is a course suspension

is when it is above 1um and it feels gritty

what is a colloidal suspension

its below 1um and tyndall effect which is blue light shattering. It's below 1 μm and has a Tyndall effect,

what are properties of well formulated suspension

a disperse phase particle should be small, uniformly sized and not settle too quickly. it should not sediment too quick which is difficult to disperse. successive doses should contain the same amount of suspended solid and uniform dose. it should be easily dispersed. it should have acceptable taste texture and ordor. and it should resist microbial growth

what are some advantages of medicinal suspensions

it has easier swallowing in children and elderly, there is good taste masking and bitterness is unoticable. high surface area makes it have faster dissolution. its very useful for absorbants and antacids as it has a high surface area.

how fast do suspensions dissolve

faster than tablets but slower than solutions

what happens when some drugs hydrolse in the presence of water

they lose their efficacy

what are disadvantages of oral suspensions

sedimentation can occur in disperse phase. it settles as a deflocculated sediment, slow sedimentatiion leading to a firm mass that is impossible to resuspend. or it settles as a flocculated sediment where fast sedimentation forms a loose cake that can be resuspended easily, both of these leads to inaccurate dosing. the presence of water can result i hydrolytic degregation with time.

what is aggregation

a collection of individual particles in a group

what is coagulation

where particles approaching each other have sufficient energy to overcome repulsive forces. it makes formation of compact aggregates. these ar held together by strong net attractive forces.

can compact aggregates be broken down

no so the product is irreversible

what happens during sedimentation of a flocculated system

the rate of sedimentation is fast and appearance can alter after a few minutes of shaking. a cloudy sediment is discernible after a few minutes. sediment exhibits higher volume due to loose open structure of floccules and large amount of liquid.

what happens during sedimentation of deflocculated suspension

the rate of sedimentation is slow and there is no apparent change for some time after shaking, it takes many hours to form a small amount of sediment. it takes weeks or months to form complete sediment. overtime the sediment becomes compacted and contains very little trapped liquid. virtually impossible to resuspend the cake.

what is true for the degree of sedimentation

they must contain the same concentration of drug, the containers must have the same dimensions, measurements should be taken when sedimentation is complete, f values are higher for flocculated suspensions

what does the b value relate to

it relates the volume of a flocculated sediment to that of a deflocculated sediment

what is a diffusible solid

it is an insoluble solid that can be suspended in a continuous phase for a sufficient length of time so that a dose can be measured.

what is an indiffusible solid

an insoluble solid that cant be suspended in a continous phase for a sufficient length of time to measure a metered dose without the use of a suspending agent

what must we ensure with the particle size of a drug

its small to ensure a slow rate of sedimentation

what does a size of less than 5um give

a gritty texture to the oral suspension

why is narrow particle size distribution is preferred

it lessens the chance of ostwald ripening. it is when small particles dissolve and recrystallise on larger particles, causing a shift in the particle size distribution.

what can hydrophillic collouds do

it coat the surface of solid hydrophobic particles with a multimolecular layer. this impacts hydrophilic character to the surface of the particle promoting wetting. they have a dual role as suspending agents due to their solution viscosity characteristics can produce a deflocculated system particularly if used at a low concentation

why is water bad at preventing the sedimentation of floculatted and defloculated suspensions

its a low viscosity newtonian fluid

how can we slow down the sedimentation of flocculated or deflocculated suspensions

adding a suspension agent which increases the viscosity of the continious phase.