Pharmacology: Drugs and Their Targets
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Questions and Answers

What is the mechanism of action of Benzodiazepines in anxiety?

  • Inhibiting serotonin re-uptake
  • Inhibiting GABA-activated Cl- channel opening
  • Blocking cyclooxygenase
  • Enhancing GABA-activated Cl- channel opening (correct)

    • Fluorouracil is an analgesic that inhibits cyclooxygenase.

    False

    What is the effect of ethanol on drug metabolism?

    increased drug metabolism leading to lower plasma concentrations

    Barbiturates increase metabolism, resulting in lower response to _______.

    <p>drugs</p> Signup and view all the answers

    Match the following drugs with their mechanisms of action:

    <p>Fluoxetine = Inhibits serotonin re-uptake Paracetamol = Inhibits cyclooxygenase Ciclesonide = Converted to active metabolite in the lung Amphetamine = CNS stimulant using noradrenaline transporter</p> Signup and view all the answers

    GABA is an excitatory neurotransmitter.

    <p>False</p> Signup and view all the answers

    What is the main site of action of Glycine?

    <p>spinal cord</p> Signup and view all the answers

    ³-aminobutyric acid (GABA) is formed from _______.

    <p>glutamate</p> Signup and view all the answers

    Why is thiopental not used for anesthesia maintenance?

    <p>It is highly lipophilic and stored in fat</p> Signup and view all the answers

    Probenecid increases the action of cephalexin by inhibiting OAT1/OAT3.

    <p>True</p> Signup and view all the answers

    What are two important drug-binding plasma proteins?

    <p>alpha 1 acid glycoprotein and human serum albumin (HSA)</p> Signup and view all the answers

    Phenobarbital ______________ CYP expression, reducing drug effects due to enhanced hepatic metabolism.

    <p>increases</p> Signup and view all the answers

    How does ritonavir cause CYP inhibition?

    <p>Irreversible inhibition of an enzyme due to formation of a complex between the enzyme and reactive metabolite via covalent bonding</p> Signup and view all the answers

    Which CYP does cobicistat inhibit?

    <p>CYP3A4</p> Signup and view all the answers

    Match the following statements with their corresponding effects:

    <p>Thiopental = Hangover effect due to slow release from fat Probenecid = Increases action of cephalexin by inhibiting OAT1/OAT3 Phenobarbital = Increases CYP expression, reducing drug effects due to enhanced hepatic metabolism Ritonavir = Irreversible inhibition of CYP3A4 due to formation of a complex between the enzyme and reactive metabolite via covalent bonding</p> Signup and view all the answers

    Ritonavir inhibits CYP2D6.

    <p>False</p> Signup and view all the answers

    What type of antifungal drug is Terbinafine?

    <p>Allylamine</p> Signup and view all the answers

    Itraconazole is a type of protease inhibitor.

    <p>False</p> Signup and view all the answers

    What is the mechanism of action of Integrase inhibitors?

    <p>Inhibiting integrase, an enzyme essential for HIV replication.</p> Signup and view all the answers

    Chloramphenicol is a type of bacterial _____________.

    <p>PSI</p> Signup and view all the answers

    What is the effect of Ritonavir on protease inhibitors?

    <p>It boosts their action</p> Signup and view all the answers

    Match the following antifungal drugs with their characteristics:

    <p>Terbinafine = Treats fungal nail infections Itraconazole = Alters cell membrane integrity or permeability Azoles = Inhibits ergosterol biosynthesis</p> Signup and view all the answers

    What is the enzyme involved in the conversion of codeine to morphine?

    <p>CYP2D6</p> Signup and view all the answers

    Esterase is involved in the hydrolysis of ______________ to tenofovir.

    <p>tenofovir disoproxil</p> Signup and view all the answers

    What is the primary effect of 5-hydroxytryptamine (5HT) on the body?

    <p>Increases motility, vasodilation, and platelet aggregation</p> Signup and view all the answers

    Glutamate is a fast-acting excitatory neurotransmitter in the CNS.

    <p>True</p> Signup and view all the answers

    What is the effect of Suxamethonium on the body?

    <p>Neuromuscular block and paralysis</p> Signup and view all the answers

    Morphine and Codeine are linked to pharmacological effects of a drug, showing a ______________________ relationship.

    <p>dose-response</p> Signup and view all the answers

    Match the following drugs with their effects:

    <p>Penicillin = Respiratory depression TOCP = Delayed neuropathy - muscle weakness ataxia Thalidomide = Severe birth defects</p> Signup and view all the answers

    Diethylstilbestrol is a human teratogen.

    <p>True</p> Signup and view all the answers

    Fetal alcohol syndrome is characterized by effects from ______________________ exposure.

    <p>prenatal alcohol</p> Signup and view all the answers

    What type of adverse drug reaction is unexpected and unpredictable?

    <p>Type B ADR</p> Signup and view all the answers

    What is the major metabolite of morphine?

    <p>Morphine-3-glucuronide</p> Signup and view all the answers

    Sodium bicarbonate can prevent salicylate overdose by decreasing urine pH.

    <p>False</p> Signup and view all the answers

    What is the enzyme responsible for metabolizing ethanol?

    <p>alcohol dehydrogenase</p> Signup and view all the answers

    Charcoal prevents aspirin overdose by having ______________ on its surface that the drug molecules attach to.

    <p>pores</p> Signup and view all the answers

    Match the following drug transporters with their types:

    <p>MDR1 = ATP-binding cassette (ABC) drug transporter OAT1 = Solute carrier (SLC) transporter BCRP = ATP-binding cassette (ABC) drug transporter</p> Signup and view all the answers

    What is the reason why pregnant people or young children should avoid tetracyclines?

    <p>They have a high affinity for calcium and slowly accumulate in bones and teeth</p> Signup and view all the answers

    Paracetamol is metabolized by UGT2B7.

    <p>False</p> Signup and view all the answers

    What is the name of the enzyme responsible for metabolizing paracetamol?

    <p>GST (Glutathione S-transferase)</p> Signup and view all the answers

    Glutamate is a fast-acting ______ neurotransmitter in the CNS

    <p>excitatory</p> Signup and view all the answers

    5-hydroxytryptamine (5HT) activates ______ channel receptors, increases motility, vasodilation, and platelet aggregation

    <p>ion</p> Signup and view all the answers

    Suxamethonium is a ______ muscle relaxant/paralysis

    <p>short-acting</p> Signup and view all the answers

    Type A ADR shows a ______ relationship

    <p>dose-response</p> Signup and view all the answers

    Penicillin - Type B ADR is characterized by ______ adverse drug reactions

    <p>idiosyncratic</p> Signup and view all the answers

    Teratogens - Type D ADR occurs ______ use

    <p>after</p> Signup and view all the answers

    TOCP is an ______ causing delayed neuropathy, muscle weakness, and ataxia

    <p>organophosphate</p> Signup and view all the answers

    Fetal alcohol syndrome is characterized by effects from ______ exposure

    <p>prenatal alcohol</p> Signup and view all the answers

    Benzodiazepines enhance ______ -activated Cl- channel opening for anxiety

    <p>GABA</p> Signup and view all the answers

    Paracetamol is an analgesic that inhibits ______ enzyme as drug targets

    <p>cyclooxygenase</p> Signup and view all the answers

    Fluorouracil blocks ______ synthesis by replacing uracil in purine biosynthesis

    <p>DNA</p> Signup and view all the answers

    Ciclesonide is a ______ converted to active metabolite in the lung

    <p>prodrug</p> Signup and view all the answers

    Fluoxetine inhibits ______ re-uptake for antidepressant effect

    <p>serotonin</p> Signup and view all the answers

    Amphetamine is a CNS stimulant that uses ______ transporter to enter nerve terminals

    <p>noradrenaline</p> Signup and view all the answers

    GABA (³-aminobutyric acid) activates ______ channel receptors, inhibitory transmitter

    <p>ion</p> Signup and view all the answers

    Glycine activates ______ channel receptors, stimulates glycine receptors, inhibitory neurotransmitter mainly in the spinal cord

    <p>ion</p> Signup and view all the answers

    Paracetamol is associated with ______ type of DILI.

    <p>intrinsic</p> Signup and view all the answers

    NSAIDs are associated with ______ type of DILI.

    <p>idiosyncratic</p> Signup and view all the answers

    Diclofenac causes ______ liver injury.

    <p>idiosyncratic</p> Signup and view all the answers

    Penicillin inhibits ______ wall synthesis.

    <p>bacterial cell</p> Signup and view all the answers

    Aminoglycosides inhibit ______ protein synthesis.

    <p>bacterial</p> Signup and view all the answers

    Amphenicols inhibit ______ protein synthesis.

    <p>bacterial</p> Signup and view all the answers

    Macrolides inhibit ______ synthesis.

    <p>protein</p> Signup and view all the answers

    Echinocandin is an ______ drug inhibiting cell wall synthesis.

    <p>antifungal</p> Signup and view all the answers

    ______ are synthetic antifungal drugs altering cell membrane integrity or permeability

    <p>Allylamines</p> Signup and view all the answers

    ______ is an allylamine treating fungal nail infections

    <p>Terbinafine</p> Signup and view all the answers

    Azoles are synthetic antifungal drugs, altering cell membrane __________ or permeability

    <p>integrity</p> Signup and view all the answers

    Tenofovir disoproxil fumarate is a prodrug for HIV reverse _________ inhibition

    <p>transcriptase</p> Signup and view all the answers

    Tenofovir alafenamide is a prodrug of tenofovir with improved oral absorption for _________ treatment

    <p>HIV</p> Signup and view all the answers

    Ritonavir is a potent _________ inhibitor used to boost protease inhibitors

    <p>CYP3A4</p> Signup and view all the answers

    Esterase hydrolyses _________ disoproxil to tenofovir

    <p>tenofovir</p> Signup and view all the answers

    Codeine is converted to morphine by the enzyme _________

    <p>CYP2D6</p> Signup and view all the answers

    Morphine is metabolised to morphine-3-glucuronide and morphine-6-glucuronide by the enzyme ______.

    <p>UGT2B7</p> Signup and view all the answers

    Entero-hepatic recirculation involves ______ metabolism, conjugates excreted into bile, and glucuronides in the GI tract being hydrolysed by B-glucuronidase.

    <p>hepatic</p> Signup and view all the answers

    Paracetamol is metabolised by the enzyme ______.

    <p>GST</p> Signup and view all the answers

    Activated charcoal prevents aspirin overdose by having ______ on its surface that the drug molecules attach to.

    <p>pores</p> Signup and view all the answers

    Sodium bicarbonate prevents salicylate overdose by ______ urine pH, increasing salicylic acid ionsisation, and decreasing reabsorption.

    <p>alkalising</p> Signup and view all the answers

    Three important ATP-binding cassette (ABC) drug transporters are ______, MRP2, and BCRP.

    <p>MDR1</p> Signup and view all the answers

    Ethanol is metabolised to acetaldehyde by the enzyme ______.

    <p>alcohol dehydrogenase</p> Signup and view all the answers

    Pregnant people or young children should avoid tetracyclines because they have a high affinity for ______ and slowly accumulate in bones and teeth.

    <p>calcium</p> Signup and view all the answers

    Study Notes

    Benzodiazepines

    • Enhance GABA-activated Cl- channel opening for anxiety

    Analgesic

    • the enzyme responsible for the production of prostaglandins, which are hormones that can cause pain and inflammation. This inhibition explains paracetamol's use as an analgesic and anti-inflammatory medication.

    Anti-Cancer Drug

    • Fluorouracil blocks DNA synthesis by replacing uracil in purine biosynthesis

    Prodrugs

    • Ciclesonide is converted to active metabolite in the lung
    • Codeine is converted to morphine via CYP2D6
    • Tenofovir disoproxil is hydrolysed to tenofovir by esterase

    Neurotransmitters

    • GABA, also known as γ-aminobutyric acid, is a major inhibitory neurotransmitter in the central nervous system, responsible for reducing the activity of neurons.
    • Glycine is an inhibitory neurotransmitter, activates ion channel receptors, and is mainly found in the spinal cord
    • Glutamate is a fast-acting excitatory neurotransmitter, activates ion channel receptors, and is found in the CNS
    • 5-hydroxytryptamine (5HT) activates ion channel receptors, increases motility, vasodilation, and platelet aggregation

    Adverse Drug Reactions (ADRs)

    • Type A ADRs are related to pharmacological effects and show a dose-response relationship (e.g., morphine)
    • Type B ADRs are idiosyncratic and unpredictable (e.g., penicillin)
    • Type D ADRs are time-related and occur after use (e.g., teratogens)
    • Type F ADRs are unexpected failures of a drug to produce therapeutic effects (e.g., antibiotic resistance)

    Organophosphates

    • TOCP causes delayed neuropathy, muscle weakness, and ataxia

    Teratogens

    • Diethylstilbestrol is a synthetic estrogen linked to severe birth defects
    • Thalidomide causes severe birth defects
    • Fetal alcohol syndrome is caused by prenatal alcohol exposure

    Antifungal Drugs

    • Allylamines alter cell membrane integrity or permeability (e.g., terbinafine)
    • Azoles alter cell membrane integrity or permeability and inhibit ergosterol biosynthesis (e.g., itraconazole)

    Anti-HIV Drugs

    • Integrase inhibitors (e.g., elvitegravir) and protease inhibitors (e.g., ritonavir) are used to treat HIV
    • Tenofovir disoproxil fumarate is a prodrug for HIV reverse transcriptase inhibition

    Metabolism

    • Enterohepatic recirculation involves lipophilic drug absorption, hepatic metabolism, conjugate excretion into bile, and hydrolysis by B-glucuronidase
    • Ethanol is metabolized to acetaldehyde via alcohol dehydrogenase
    • Probenecid inhibits OAT1 and OAT3, increasing the action of Cephalexin is a first-generation cephalosporin antibiotic that inhibits bacterial cell wall synthesis. It is effective against a wide range of gram-positive and gram-negative bacteria, including Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, and E. coli. Cephalexin is often used to treat respiratory tract infections, skin and soft tissue infections, and urinary tract infections.

    Drug Interactions

    • Ritonavir, also known as Norvir, is a potent inhibitor of cytochrome P450 3A4 (CYP3A4), one of the primary enzymes responsible for the metabolism of various medications. Its primary use is as a pharmacokinetic enhancer for protease inhibitors, increasing their bioavailability and potency.
    • Cobicistat is a pharmacokinetic enhancer that is used in combination with elvitegravir, an HIV-1 integrase inhibitor, to treat HIV infection. Cobicistat increases the bioavailability and efficacy of elvitegravir by inhibiting its metabolism.
    • Phenobarbital induces CYP expression, reducing drug effects due to enhanced hepatic metabolism

    Benzodiazepines and Anxiety

    • Benzodiazepines enhance GABA-activated Cl- channel opening for anxiety.

    Analgesic and Anti-Cancer Drugs

    • Paracetamol is an analgesic that inhibits cyclooxygenase.
    • Fluorouracil is an anti-cancer drug that blocks DNA synthesis by replacing uracil in purine biosynthesis.

    Respiratory and Antidepressant Drugs

    • Ciclesonide is a prodrug converted to active metabolite in the lung.
    • Fluoxetine inhibits serotonin re-uptake for antidepressant effect.

    CNS Stimulants and Toxicity

    • Amphetamine is a CNS stimulant that uses noradrenaline transporter to enter nerve terminals and replace/release neurotransmitters noradrenaline and serotonin.
    • Ethanol increases drug metabolism leading to lower plasma concentrations.
    • Chronic ethanol consumption leads to evidence of toxicity including acute toxicity - CNS depression and chronic toxicity - alcohol-related liver disease.

    Barbiturates and Neurotransmitters

    • Barbiturates increase metabolism resulting in lower drug response.
    • GABA (³-aminobutyric acid) activates ion channel receptors and is an inhibitory transmitter formed from glutamate.
    • Glycine activates ion channel receptors, stimulates glycine receptors, and is an inhibitory neurotransmitter mainly in the spinal cord.
    • Glutamate activates ion channel receptors, stimulates glutamate receptors, and is a fast-acting excitatory neurotransmitter in the CNS.
    • 5-hydroxytryptamine (5HT) activates ion channel receptors, increases motility, vasodilation, and platelet aggregation.

    Muscle Relaxants and Pharmacological Effects

    • Suxamethonium is a long-acting agonist causing neuromuscular block and is a short-acting muscle relaxant/paralysis.
    • Morphine and codeine are linked to pharmacological effects and show a dose-response relationship.
    • Morphine and codeine are associated with type A ADR, which includes respiratory depression.

    Adverse Drug Reactions (ADRs)

    • Type B ADR is idiosyncratic, unpredictable adverse drug reactions, such as anaphylaxis seen with penicillin.
    • Type D ADR is time-related, occurs after use, and includes agents causing birth defects by altering fetal growth.
    • Type F ADR is antibiotic resistance, which is an unexpected failure of a drug to produce therapeutic effects.

    Teratogens and Toxic Substances

    • Diethylstilbestrol is a synthetic estrogen linked to severe birth defects, including clear-cell adenocarcinoma in the vagina of female offspring of DES-treated mothers.
    • Thalidomide is a sedative causing severe birth defects.
    • Fetal alcohol syndrome results from prenatal alcohol exposure, including facial defects.

    Liver Injury and Toxicity

    • Paracetamol type DILI is intrinsic, predictable, common, dose-related, and reproducible in animal models.
    • NSAIDs type DILI cause idiosyncratic liver injury, which is rare, unpredictable, not dose-related, and not reproducible in animal models.
    • Diclofenac causes idiosyncratic liver injury due to reactive metabolites causing mitochondrial injury and oxidative stress.

    Antibacterial Drugs

    • Penicillin inhibits bacterial cell wall synthesis.
    • Amoxicillin is a broad-spectrum penicillin not β-lactamase resistant.
    • Clavulanic acid is a β-lactamase inhibitor, semisynthetic.
    • Augmentin is a combination drug for penicillin resistance, consisting of amoxicillin and clavulanic acid.
    • Cephalosporin inhibits bacterial cell wall synthesis.

    Anti-HIV Drugs

    • Integrase inhibitors are a mechanism of action for anti-HIV drugs, including INSTIs such as elvitegravir.
    • Protease inhibitors are anti-HIV drugs that inhibit viral protease, including PIs such as navir.

    miscellaneous

    • Codeine is a prodrug example, converted to morphine by CYP2D6 (dealkylation).
    • Esterase hydrolyzes tenofovir disoproxil to tenofovir.
    • Morphine is metabolized to morphine-3-glucuronide and morphine-6-glucuronide by UGT2B7.
    • Enterohepatic recirculation occurs with morphine, undergoing absorption, hepatic metabolism, conjugates excreted into bile, glucuronides in the GI tract hydrolysed by β-glucuronidase, and generating unconjugated drug.

    Drug Metabolism and Elimination

    • Paracetamol is metabolized to NAPQI by GST.
    • Activated charcoal prevents aspirin overdose by adsorbing the drug, which is then excreted from the body.
    • Sodium bicarbonate prevents salicylate overdose by alkalizing urine, increasing urine pH, increasing salicylic acid ionization, and decreasing reabsorption.
    • MDR1, MRP2, and BCRP are important ATP-binding cassette (ABC) drug transporters.
    • OAT1 and OAT3 are solute carrier transporters (SLC).
    • Ethanol is stored in total body water.
    • Ethanol is metabolized to acetaldehyde by alcohol dehydrogenase (oxidation).
    • Ethanol follows zero-order kinetics.
    • Tetracyclines should be avoided in pregnant people or young children due to their high affinity for calcium, which slowly accumulates in bones and teeth.

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