FREE Master of Chemistry: Pharmaceutical Chemistry Questions and Answers
What theory of drug-receptor interactions maintains that a receptor is in a state of dynamic equilibrium between an activated form (Ro), which is responsible for the biological response, and an inactive form (To), even in the absence of drugs?
The drug-receptor interaction theory that states "even in the absence of drugs, a receptor is in a state of dynamic equilibrium between an activated form (Ro), which is responsible for the biological response, and an inactive form (To)" is the "Activation-Aggregation Theory." This theory suggests that drugs can either stabilize the activated form (Ro) or inhibit the activation, leading to the inactive form (To). The equilibrium between these forms determines the biological response to the drug.
Which of the following is an illustration of a bioisosteric replacement cyanomino group for thioamide?
Metiamide and Cimetidine are both H2 receptor antagonists used to reduce stomach acid production. Cimetidine, in particular, replaced the thioamide group in Metiamide with a cyanoimino group, leading to improved properties and reduced side effects.
By converting its phenolic groups to Bis-dimethylcarbamate, which would otherwise undergo rapid pre-systemic metabolism, bambuterol is the prodrug of this medication used to treat asthma.
Bambuterol is a prodrug that is converted to terbutaline in the body. Prodrugs are inactive or less active compounds that are converted into active drugs after administration within the body. In the case of bambuterol, it is designed to have prolonged action and reduced rapid pre-systemic metabolism by converting its phenolic groups to Bis-dimethylcarbamate, which is then metabolized to release terbutaline, an adrenergic receptor agonist used to treat asthma and other respiratory conditions.
This is the only common amino acid that contains an electrophilic side chain and can be changed with suitable nucleophilic agents when creating covalently binding enzyme inhibitors.
Serine has a hydroxyl (-OH) group on its side chain, which can act as a nucleophile in chemical reactions. This makes it suitable for forming covalent bonds with electrophilic groups on drugs designed to inhibit specific enzymes. The process of forming a covalent bond between the inhibitor and the enzyme's active site is known as "covalent inhibition" or "mechanism-based inactivation."
In the presence of sodium amide, 3-chloro-N-phenylbenzeneamine reacts with sulfur before being alkylated with 3-o-dimethylaminopropyl chloride.
Alprazolam is a benzodiazepine medication used to treat anxiety and panic disorders. The synthetic route you described is one of the methods used for the preparation of alprazolam.
Which of the following medications has two isomers, R and S, that compete with one another to engage the enzyme binding site, inhibiting the metabolism of the other isomer?
Warfarin is an anticoagulant medication used to prevent the formation of blood clots. It exists as a racemic mixture of two isomers: R-warfarin (the more potent isomer) and S-warfarin. Both isomers are metabolized by the same enzyme system in the liver, namely cytochrome P450 enzymes, particularly CYP2C9.
Which medication from the list below is not regarded as a lead molecule's fragmented analog?
Fragment-based drug design is a strategy used in drug discovery where smaller fragments of molecules are used as starting points to design and develop new drugs. The other three drugs in the options (Levorphanol, Metazocine, and Codeine) are considered as fragmented analogs of a lead molecule, which means they are derived from a lead molecule by fragmenting and modifying its structure. However, Meperidine is not typically considered as a fragmented analog in the context of this drug design approach.
In the aforementioned reaction, dichlorocarbene, a reactive intermediate, transforms phenol into 2-hydroxy benzaldehyde.
In the Reimer-Tiemann reaction, phenol reacts with chloroform (CHCl3) and a base, usually a strong hydroxide like sodium hydroxide (NaOH), to generate the dichlorocarbene intermediate. The dichlorocarbene then reacts with the phenol to yield 2-hydroxybenzaldehyde and an inorganic chloride salt.
Which of the following is an example of a medicine with a rationally chosen mechanism as its basis?
Vigabatrin is an example of a rationally designated mechanism-based inactivator drug. Rationally designated mechanism-based inactivators, also known as suicide inhibitors, are drugs that are specifically designed to bind to an enzyme's active site and undergo a chemical reaction that leads to the irreversible inactivation of the enzyme. These drugs are often used in the treatment of diseases where inhibiting a specific enzyme is therapeutically beneficial. Vigabatrin is an antiepileptic drug that acts by irreversibly inhibiting the enzyme GABA transaminase, which increases gamma-aminobutyric acid (GABA) levels in the brain, leading to reduced seizure activity.
The 4-amino-5-nitrosopyrimidine and phenylacetonitrile process was originally used to create which of the following drugs?
Trimethoprim is an antibiotic used to treat various bacterial infections, particularly urinary tract infections. The synthesis of Trimethoprim involves the reaction of 4-amino-5-nitrosopyrimidine with phenylacetonitrile to form the active pharmaceutical ingredient, Trimethoprim.
Which of the following types of enzyme inhibitors is irreversible?
A suicide inhibitor, also known as a mechanism-based inactivator or a rationally designated irreversible inhibitor, is a type of enzyme inhibitor that irreversibly binds to the enzyme's active site and inactivates it. It forms a covalent bond with the enzyme, leading to the permanent loss of the enzyme's activity. This type of inhibitor is usually designed to mimic the substrate and undergo a chemical reaction with the enzyme, resulting in its inactivation.
Which of the following chemical reactions produces 2,3-epoxyalcohols from primary and secondary allylic alcohols in an enantioselective manner?
In the Sharpless epoxidation, a chiral, stoichiometric or catalytic, metal-based oxidizing agent (often using titanium or other transition metals) is used to selectively introduce an oxygen atom into the allylic double bond of an allylic alcohol, leading to the formation of a chiral epoxide (2,3-epoxyalcohol). The reaction is highly enantioselective, meaning it produces predominantly one enantiomer of the product, which is valuable in asymmetric synthesis and the preparation of complex chiral molecules.
In this described reaction, which is thought to take place in two phases and involves an aldehyde, a dicarbonyl, and ammonia, the dicarbonyl and ammonia first condense to produce a diimine with an unusual orientation of N-H groups:
In the Debus-Radziszewski imidazole synthesis, the first step involves the reaction of a dicarbonyl compound (usually a 1,2-diketone) and ammonia to form a diimine intermediate. This diimine intermediate has an unusual orientation of N-H groups, which makes it different from the usual imines. In the second step, the diimine reacts with an aldehyde, leading to the formation of an imidazole ring. The reaction sequence is an important method for the synthesis of imidazoles, which are heterocyclic compounds containing a five-membered ring with two nitrogen atoms.
Which of the following is a xanthene oxidase enzyme inhibitor that works to stop the production of uric acid and treat gout?
Allopurinol is a medication used to lower uric acid levels in the blood. It works by inhibiting the activity of xanthine oxidase, an enzyme involved in the breakdown of purines in the body. By inhibiting xanthine oxidase, allopurinol reduces the production of uric acid, which is beneficial in the treatment and prevention of gout, a condition characterized by elevated levels of uric acid leading to painful joint inflammation.
Which of the following antitubercular medications is known to cause blindness while the (S,S)-(+)-enantiomer is used to treat tuberculosis?
Ethambutol is an important component of the first-line treatment for tuberculosis. It is used in combination with other antitubercular drugs to effectively treat the disease. However, ethambutol can cause optic neuropathy, which can lead to vision loss, especially when the (R,R)-(-)-enantiomer is present in the drug formulation. The (S,S)-(+)-enantiomer is less likely to cause this side effect and is used for its therapeutic effects against tuberculosis.
Which of the following antiviral medications inhibits DNA polymerase and is an adenosine analog?
Vidarabine, also known as adenine arabinoside or Ara-A, is an antiviral medication that is structurally similar to adenosine. It interferes with the replication of DNA viruses by inhibiting the action of viral DNA polymerase, an enzyme essential for viral DNA synthesis. Vidarabine is mainly used to treat viral infections caused by herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) and varicella-zoster virus (VZV).