Incompatibilities Flashcards
Incompatibilities
Result from undesirable reactions or antagonisms that occur when two or more drugs are compounded together
Incompatibilities
Affect the efficacy, safety, and appearance of a med.
Incompatibilities can result in
A) modification of the effect of the API, such as an increase in toxicity
B) decrease in solubility or stability
IV drugs can’t be mixed with all available IV fluids
True because micro crystals may be formed
Incompatibilities
Can occur when some preparations are diluted, eg, CHLOROXYLENOL.
Incompatibilities
May result in potentiation of one drug which may be harmful
Types of incompatibilities
- Physical
- Chemical
- Therapeutic
Tetracycline( antibiotics) + milk or iron preparations =
A non-absorbable complex
Physical incompatibilities
Physical changes that when two or more drugs subs. are mixed together
Unsightly, non-uniform products are produced, which makes the removal of accurate dose difficult.
Physical incompatibilities are caused by;
- Immiscibility
- Insolubility
- Liquefaction
Insolubility
Occurs when solute is insoluble in liquid medium Eg. Chalk, aromatic chalk, scuccinyl- sulphathiazole and sulphadimidine and calamine and zinc etc
Insolubility can be solved by
Using a thickening agent
Insolubility
Those solutes difficult to wet with water are wetted with wetting agents.
Eg. Corticosteroids, antibiotics, and sulphur.
Insolubility
Wetting agents disperse the powder and prevent the formation of a slowly dispersing solid- stabilised foam on shaking.
Wetting agents: Saponins
Sulphur containg lotions,
Wetting agents: polysorbate
for parenteral suspension of corticosteroids and antibiotics
Immiscibilit aryre
Used arthmai
Immiscibility
.rather around atgee
Liquefaction
Proceeds with eutectic mixture formation
Liquefaction subs
1.camphor
2. Thymol
3. Phenol
4. Menthol
5. Aspirin + phenanazone
Note : there’s absolutely no problem dispensing these in other forms aside powders
Liquefaction can be solved by
Adding a lot of diluent
Liquefaction
Diluents prevent drugs from coming together
Characteristics of a good diluent
- High melting point
- Large surface area
Chemical incompatibilities
Maybe caused by change in ph, double decomposition reaction, complex formation
Types of chemical incompatibilities
If product is harmless
- Adjusted chemical incompatibilities
- Tolerated chemical incompatibilities
Addition a resinous tincture to water=
Formation of indiffusible cloats
Add slowly undiluted tincture to a diluted dispersion of colloid
Dispersions of hydrophilic colloids such as polysaccharide mucilage =
Precipitated by high concentrations of alcohol or salt
Prevented by adequate dilution and addition of small amounts with vigorous stirring