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Which of the following is a characteristic of macromolecular complexes formed with poorly soluble drugs?
Which of the following is a characteristic of macromolecular complexes formed with poorly soluble drugs?
What is the primary benefit of adding a soluble material to a poorly soluble drug to form a complex?
What is the primary benefit of adding a soluble material to a poorly soluble drug to form a complex?
In the context of chemical modification to enhance solubility, what is the purpose of forming a salt from poorly soluble acids and bases?
In the context of chemical modification to enhance solubility, what is the purpose of forming a salt from poorly soluble acids and bases?
Which of the following is NOT a reason for using nonaqueous solutions in pharmaceuticals?
Which of the following is NOT a reason for using nonaqueous solutions in pharmaceuticals?
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Which solvent is primarily used for the injection of medications like Diazepam and is known to be toxic?
Which solvent is primarily used for the injection of medications like Diazepam and is known to be toxic?
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What is the characteristic of cyclodextrins that enables them to improve the solubility of poorly water-soluble drugs?
What is the characteristic of cyclodextrins that enables them to improve the solubility of poorly water-soluble drugs?
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Which of the following fixed oils is NOT typically used for parenteral products?
Which of the following fixed oils is NOT typically used for parenteral products?
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Which of the following statements about dimethylsulphoxide (DMSO) is accurate?
Which of the following statements about dimethylsulphoxide (DMSO) is accurate?
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Which of the following solvents is commonly used in cosmetics and is also known for its role as a non-therapeutic cosolvent?
Which of the following solvents is commonly used in cosmetics and is also known for its role as a non-therapeutic cosolvent?
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What characteristic differentiates fixed oils from volatile oils?
What characteristic differentiates fixed oils from volatile oils?
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Study Notes
Complexation
- Combining a poorly soluble drug with a soluble substance creates a soluble intermolecular complex.
- Most complexes are macromolecular and inactive, as they cannot cross lipid membranes. Complex formation is easily reversed.
- Many complexes are not water-soluble, resulting in prolonged drug release.
- Example: Polyvinylpyrrolidone (PVP) and iodine improve iodine's aqueous solubility.
- Another example: Cyclodextrins are a series of glucopyranose units forming hollow cylindrical structures (conical).
- The inside surface of cyclodextrins is hydrophobic (-CH₂), while the outer surface is hydrophilic (OH).
- Poorly water-soluble drugs fit within the hydrophobic interior of cyclodextrins, forming a freely water-soluble inclusion complex.
Chemical Modification
- Increasing the aqueous solubility of poorly soluble acids and bases involves converting them to salts.
- Example: The synthesis of sodium phosphate salts of hydrocortisone, prednisolone, and betamethasone.
Nonaqueous Solutions - Uses
- Stability: propionate and benzoate esters of testosterone and estradiol form depot preparations.
- Choice: factors for selecting non-aqueous solvents include toxicity, irritancy, sensitization, flammability, cost, stability, and compatibility with other excipients.
Classification of Nonaqueous Solvents - 1: Fixed Oils
- Vegetable origin, non-volatile, primarily fatty acid esters of glycerol.
- Almond oil (oleic acid): for oily phenol injections.
- Castor oil: solvent for miconazole eye drops.
- Other oils (olive, sesame, maize, cottonseed, soya, castor): used parenterally or externally (emulsions).
Classification of Nonaqueous Solvents - 2: Alcohols
- Ethyl alcohol: external use (e.g., cooling lotions, salicylic acid lotions).
- Industrial methylated spirit (IMS).
- Isopropyl alcohol: use in pharmaceuticals, but potential for abuse/denaturation.
Classification of Nonaqueous Solvents - 3: Polyhydric Alcohols
- Glycols: toxic.
- Propylene glycol: used in Diazepam Injection, Co-trimoxazole IV Infusion, Chloramphenicol Ear Drops, and hydrocortisone ear drops.
- PEG400: cosolvent with water (glycerol), used in water-miscible ointment bases and clotrimazole topical solutions.
Classification of Nonaqueous Solvents - 4: Dimethyl Sulfoxide (DMSO)
- Highly polar.
- Aids drug penetration through skin; primarily used in veterinary drugs.
- Idoxuridine (application to human skin).
Classification of Nonaqueous Solvents - 5: Ethyl Ether
- Not for internal use (therapeutic).
- Cosolvent in some collodions and used in crude drug extraction.
Classification of Nonaqueous Solvents - 6: Miscellaneous Solvents
- Isopropyl myristate/isopropyl palmitate: cosmetics.
- Xylene: used in ear drops and to dissolve earwax.
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Description
This quiz explores the concepts of complexation in pharmaceuticals, focusing on how poorly soluble drugs can be made more soluble through the formation of intermolecular complexes. It covers examples such as cyclodextrins and the chemical modification of drugs to enhance solubility, including the conversion of acids and bases to salts.
