Classifications of Solutions:
Oral
Optic
Opthalmic
Topical
aqueous solutions containing sugar
Syrup
sweetened hydroalcoholic solutions (H2O + C2H6O)
Elixirs
solutions of
- aromatic materials (if the alcoholic)
- aromatic water (if the solvent is aqueous)
Spirits
“Fluid extracts”; solutions prepared by extracting active constituents from crude drugs.
Tinctures
Characteristics of Solutions:
advantage:
easy to swallow (pediatric, geriatric)
fast absorption rate
flexible dosing
disadvantage:
less stable < solid dosage forms
color change
precipitation
microbial growth
chemical gas formation
Solution: Steps/Processes
Step 1: Raw Material Selection
Solutes
- Active ingredients (solutes; organic medicinal agents, weak acids/weak bases)
- Excipients (stabilizers, coloring/flavoring, preservatives)
Solvents
- match specific solute (solubility, clarity, palatability, toxicity, viscosity, color, economic feasibility)
ex. H20/Aromatic H2O, OH, glycerin
Methods: Simple Solution
other ingredients: Stabilizer/solubilizer
- calcium hydroxide topical solution USP (Lime H2O)
- sodium phosphate oral solution USP
- strong iodine solution USP
Methods: Solution by chemical reaction
Preparation (reacting 2 or more solutes + suitable solvent)
ex. Magnesium citrate (magnesium carbonate w/citric acid + flavoring, sweetening agents, filtering talc & carbonating it by potassium or sodium bicarbonate)
Methods: Solution by Extraction
Methods: Solution by Distillation
Extraction (vegetable/animal origin) w/ suitable solvent. Classified as extractives.
Distilling the volatile principles from a drug inside a copper wire cage which allows the free passage of vapors and
boiling water.
Machines & Equipements (SOLUTIONS)
SOLUTION examples:
Syrups
• Ambroxol (Ambrolex) Syrup
• Ascorbi Acid (Ceelin) Syrup
• Carbocisteine (Ceascol) Syrup
• Lagundi Ascof Syrup
• Paracetamol (Tempra) Syrup
Spirits
• Aromatic ammonia spirit
• Camphor spirit
• Ethyl nitrate spirit
Elixir
• Chlorpheniramine maleate (USP) (Antihistaminic)
• Diphenydramine HCI (Antihistaminic)
Otic Solutions
• Ciprodex (ciprofloxacin/dexamethasone)
• Vosol HC (acetic acid/hydrocortisone)
• Cortisporin Otic (hydrocortisone)
Ophthalmic Solutions
• Ketorolac
• Tromethamine
• Diclofenac
• Flurbiprofen
Topical Solutions
• Aluminum acetate solution
• Calcium hydroxide topical solution
• Povidone lodine Solution
a heterogeneous system consisting of 2 phases; internal phase is dispersed uniformly throughout the external phase.
Suspension
CHARACTERISTICS of SUSPENSION:
Process SUSPENSION:
Formulation Flow:
Finely divided particles -> Particles are added in dispersion medium -> Wetting agent is added -> Deflocculated suspension
Methods: Precipitation
Three precipitation methods used:
1. Organic solvent precipitation - H2O insoluble drugs can be precipitated by dissolving them in water- miscible organic solvent and then + organic phase to distilled water under standard conditions.
Eg. Organic solvents used are ethanol, methanol, propylene glycol and polyethylene glycol.
2. Precipitation by pH - changing the pH of medium is more readily accomplished and does not present the same difficulties associated with organic solvent precipitation. Applicable only to those drugs in which solubility is dependent on pH value.
Eg. Estradiol Suspension and Insulin Suspension.
3. Double Decomposition - involves simple chemistry,
Eg While Lotion (NF XIII).
Method: Dispersion
Vehicle must be formulated so that solid phase is easily wetted & dispersed.
Use of surfactant is desirable to ensure uniform wetting of hydrophobic solid.
Use of suspending agent such as synthetic polymer, natural gums and others may be indicated depending upon specific application.
Actual dispersing of solids may/may not cause particle size reduction. If particle size reduction occurs, the particles obtained may have different solubilities and this may lead to super saturation of the system.
Method: Use of Controlled Flocculation
Controlled flocculation of particles is obtained by adding flocculating agents, which are: Electrolytes, Surfactants, Polymers
GENERATING NEW DESIGNS FOR DRUG FORMULATION:
Machines/Equipment SUSPENSION:
SUSPENSION examples:
Dry, solid substance, finely divided drugs with/without excipient that is intended for internal/external use.
Finely divided state (10nm-1000 μm)
Obtained by crushing, grinding, or comminuting.”
Powders
Methods in Powders:
POWDERS CAN BE CLASSIFIED AS:
1 Based on use.
2 Based on particle size
3. Based on dispensing
CLASSIFICATION BASED ON USE:
a. Pharmaceutical powders for internal use - A preparation that consist of solid, loose dry particles that can be taken orally, can be administered through the nose as snuffs or blown into the body.
b. Pharmaceutical powders for external use - Known as powders for cutaneous application thatcontain one or more active substances, with or without excipients.
CLASSIFICATION BASED ON PRTICLE SIZE
a. Very coarse powder: No. 8 sieve
b. Coarse powder: No. 20 sieve
c. Moderately coarse: No. 40 sieve
d. Fine: No. 60 sieve
e. Very fine: No. 80 sieve
CLASSIFICATION BASED ON DISPENSING:
a. Bulk powders - mixture of all the materials packed into a properly designed bulk containers, such as a tight, wide-mouthed glass or plastic bottle.
The dose of bulk powders can be affected by many factors, including: measuring device (spoon), storage humidity, degree of settling, patient factors.
b. Divided powders - are single doses of powdered drug mixtures individually enclosed in paper, plastic laminates, or metallic foil wrappers or packets