Podcast
Questions and Answers
What type of forces hold organic molecular complexes together?
What type of forces hold organic molecular complexes together?
What primarily contributes to the stability of donor-acceptor complexes?
What primarily contributes to the stability of donor-acceptor complexes?
Which drug inhibits thyroid action by tying up iodine?
Which drug inhibits thyroid action by tying up iodine?
What is the result of mixing benzoquinone and hydroquinone in equal molar concentration?
What is the result of mixing benzoquinone and hydroquinone in equal molar concentration?
Signup and view all the answers
Which acid forms complexes with weak bases and yields salts with strong bases?
Which acid forms complexes with weak bases and yields salts with strong bases?
Signup and view all the answers
How do caffeine and sulfonamide/barbiturate form a complex?
How do caffeine and sulfonamide/barbiturate form a complex?
Signup and view all the answers
What type of drugs possess a nitrogen-carbon-sulfur moiety?
What type of drugs possess a nitrogen-carbon-sulfur moiety?
Signup and view all the answers
What is the role of resonance in charge transfer complexes?
What is the role of resonance in charge transfer complexes?
Signup and view all the answers
What primarily characterizes the interior of the cyclodextrin (CD) cavity?
What primarily characterizes the interior of the cyclodextrin (CD) cavity?
Signup and view all the answers
Which cyclodextrin has the smallest cavity size and is less useful for pharmaceuticals?
Which cyclodextrin has the smallest cavity size and is less useful for pharmaceuticals?
Signup and view all the answers
How does complexation with cyclodextrin improve the solubility of retinoic acid?
How does complexation with cyclodextrin improve the solubility of retinoic acid?
Signup and view all the answers
What is a significant benefit of complexation for drug stability?
What is a significant benefit of complexation for drug stability?
Signup and view all the answers
Complexation with cyclodextrin can enhance the absorption of which drugs?
Complexation with cyclodextrin can enhance the absorption of which drugs?
Signup and view all the answers
Which of the following statements about β-cyclodextrin is NOT true?
Which of the following statements about β-cyclodextrin is NOT true?
Signup and view all the answers
What does complexation with β-cyclodextrin do to the physical state of Nitroglycerin?
What does complexation with β-cyclodextrin do to the physical state of Nitroglycerin?
Signup and view all the answers
Which is an application of complexation regarding drug dissolution?
Which is an application of complexation regarding drug dissolution?
Signup and view all the answers
What is a potential effect of complexation between polyethylene glycols (PEGs) and certain drugs?
What is a potential effect of complexation between polyethylene glycols (PEGs) and certain drugs?
Signup and view all the answers
What is the effect on Ajmaline's dissolution rate when complexed with polyvinylpyrrolidone (PVP)?
What is the effect on Ajmaline's dissolution rate when complexed with polyvinylpyrrolidone (PVP)?
Signup and view all the answers
What type of forces are involved in the complexation of caffeine with acidic drugs?
What type of forces are involved in the complexation of caffeine with acidic drugs?
Signup and view all the answers
What is one outcome of caffeine-drug complexation on the metabolism of benzocaine?
What is one outcome of caffeine-drug complexation on the metabolism of benzocaine?
Signup and view all the answers
What kind of complexes are also referred to as inclusion complexes?
What kind of complexes are also referred to as inclusion complexes?
Signup and view all the answers
Which of the following drugs were mentioned as forming complexes with caffeine?
Which of the following drugs were mentioned as forming complexes with caffeine?
Signup and view all the answers
What can caffeine-drug complexes improve, according to the content?
What can caffeine-drug complexes improve, according to the content?
Signup and view all the answers
What can be a consequence of caffeine's impact on drug pharmacokinetics?
What can be a consequence of caffeine's impact on drug pharmacokinetics?
Signup and view all the answers
Which type of host molecule typically forms tubular channels for guest molecules?
Which type of host molecule typically forms tubular channels for guest molecules?
Signup and view all the answers
What type of molecules are usually limited as guest components in channel complexes?
What type of molecules are usually limited as guest components in channel complexes?
Signup and view all the answers
What is a characteristic of clathrate compounds?
What is a characteristic of clathrate compounds?
Signup and view all the answers
Which of the following is an example of a clathrate?
Which of the following is an example of a clathrate?
Signup and view all the answers
What type of compounds do layer type complexes typically entrap?
What type of compounds do layer type complexes typically entrap?
Signup and view all the answers
Which compound is primarily formed from starch by bacterial amylase?
Which compound is primarily formed from starch by bacterial amylase?
Signup and view all the answers
What is the minimum number of glucose units in naturally occurring cyclodextrins?
What is the minimum number of glucose units in naturally occurring cyclodextrins?
Signup and view all the answers
What typically limits the use of layer type complexes?
What typically limits the use of layer type complexes?
Signup and view all the answers
Study Notes
Complexation and Protein Binding
- Organic molecules are held together by weak forces like donor-acceptor interactions, hydrogen bonds, van der Waals forces. Covalent bonds are not involved.
- Some molecules can polarize others, creating ionic interactions or charge transfer. These are often called charge transfer complexes.
- The difference between donor-acceptor and charge transfer complexes is that resonance plays a major role in complexation in charge transfer, while dispersion forces and dipole-dipole interactions are more important in donor-acceptor complexes.
- Many organic complexes are not stable enough to be isolated as distinct compounds.
Pharmaceutical Applications
- Disulfiram, clomethiazole, and tolnaftate: Used in treating alcohol addiction, as a sedative-hypnotic, and as an antifungal agent, respectively. These drugs contain nitrogen-carbon-sulfur moieties.
- Complex formation with iodine: Involves charge transfer from nitrogen or sulfur atoms to iodine. This can affect thyroid function in the body. Examples include drugs containing N-C=S moieties.
- Caffeine and sulfonamides/barbiturates: Form complexes through dipole-dipole forces and hydrogen bonds between carbonyl groups of caffeine and atoms on the other drug. This can impact drug efficiency.
- Quinhydrone type: Alcoholic solutions of benzoquinone and hydroquinone, mixed in equal molar concentrations, form a quinhydrone complex. Used in pH determination.
- Picric acid type: Forms complexes with weak bases, including salts. Butesin picrate, a complex with picric acid, combines antiseptic and anesthetic properties, used in 1% ointment for burns.
- Polymer type: Additives like polyethylene glycols, carboxymethyl cellulose, and carbowaxes contain nucleophilic oxygen and can form complexes with drugs (tannic acid, salicylic acid, phenols). Incompatibilities, such as precipitates, flocculation, and absorption/pharmacokinetic issues, can result.
- CMC + Amphetamine: A poorly absorbed combination. Ajmaline's dissolution rate is enhanced by complexation with PVP.
- Caffeine-drug complexes: Caffeine forms complexes with acidic compounds (e.g., sulfonamides, barbiturates). Examples include complexes with benzocaine, procaine, and tetracaine.
- Caffeine's effect on drugs: Caffeine significantly affects the absorption, distribution, metabolism, and excretion of various drugs, which can lead to changes in therapeutic responses, including therapeutic failure or toxic reactions.
Inclusion Complexes
- Inclusion compounds: Also called occlusion compounds, where one component is trapped within a lattice or cage-like structure formed by the other. This differs from other complex types, as the driving force for complexation is primarily the architecture of the molecules, not chemical affinity.
- Channel type: Host molecules crystallize into channels with specific characteristics. The guest molecule must fit the channel's stereochemistry, meaning only specific guest molecules can be incorporated.
- Example of channel complexes: Deoxycholic acid, urea, thiourea, amylase form channels to enclose compounds like paraffin, esters, acids and ethanol. Starch and iodine complexes are an example of a channel complex. Iodine molecules are trapped within channels formed by glucose residues in starch.
- Layer type: Guest molecules are entrapped between layers of host molecules. Examples include clays like montmorillonite that can enclose hydrocarbons, alcohols, and glycols.
- Clathrates: Compounds that form cage-like structures that trap guest molecules. Chemical bonds are not involved; the molecular size of the entrapped component is the primary factor.
Other Types of Complexes
- Cyclodextrins: Cyclic oligosaccharides with six or more glucopyranose units, formed by the action of bacterial amylase on starch. Aqueous solubility is improved by complexation.
- a-CD, β-CD, and γ-CD: Naturally occurring cyclodextrins with different numbers of glucose units. They vary in cavity size and usefulness in pharmaceutical applications. a-CD has the smallest cavity, while the others have larger cavities, leading to greater solubility enhancement potential. Hydrophobic interior and hydrophilic exterior contribute to complexation.
- CD complex applications: Enhanced solubility (retinoic acid, others), enhanced dissolution (famotidine), enhanced stability (aspirin, others), sustained release (ethylated β-CD) of drugs.
Applications of Complexation
- Solubility: Complexation enhances the solubility of drugs like para-aminobenzoic acid (PABA) with caffeine.
- Dissolution: Beta-cyclodextrins can enhance the dissolution rate of drugs, including phenobarbital.
- Physical state: Complexation can change the physical state of a drug (liquid to solid), improving processing characteristics, like in complexes with nitroglycerin using beta-cyclodextrin.
- Stability: Complexation often improves the stability of drugs, exemplified by beta-cyclodextrin complexes with vitamins A and D.
Further Aspects of Complexation
- Chemical stability: Complexation can inhibit chemical reactions, like the hydrolysis of benzocaine, when complexed with caffeine.
- Partition coefficient: Complexation enhances the partition coefficient of some drugs (like permanganate with benzene).
- Absorption and bioavailability: Complexation can reduce the absorption of tetracycline by binding to cations (e.g., Ca2+, Mg2+, Al3+). On the other hand, complexation can enhance the absorption of drugs like indomethacin.
- Reduced toxicity: β-Cyclodextrin can reduce the ulcerogenic effects of indomethacin.
Additional Applications
- Drug activity: 8-hydroxyquinoline complexes with iron exhibit greater antimalarial activity. Para-aminosalicylic acid with copper ions shows increased anti-tuberculosis activity.
- Metal poisoning antidote: Dimercaprol (BAL) is used to treat heavy metal poisoning.
- Therapeutic tool: EDTA is a blood preservative and anticoagulant.
- Assay of drugs: Complexometric titrations help analyze drugs containing metal ions.
- Volatility reduction: Cyclodextrins can protect volatile drugs with oily and volatile components from the air to thus improve stability and overcome unpleasant odors.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the complexation of organic molecules and their interactions in pharmaceutical applications. This quiz covers concepts like donor-acceptor interactions, charge transfer complexes, and the role of various compounds in medicine. Understand how these complexes function and their implications in drug development.
