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Principles Of Pharmacology > Week 9 > Flashcards

Week 9 Flashcards

1
Q

What is the overall purpose of Beta-Lactam treatment?

A

Prevention and treatment of bacterial infections.

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2
Q

By what method is Penicillin administered?

A

Injection

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3
Q

By what method are ampicillin, amoxycillin and cephalexin administered?

A

Orally

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4
Q

What is the purpose of penicillin binding protein?

A

It creates cross-links within cell walls of bacterial cells therefore giving the cells formation and strength.

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5
Q

What are the repeating units of bacterial cell walls?

A

N-acetylglucosamine and N-acetylmuramic acid.

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6
Q

Describe the structure of N-acetylmuramic acid subunits.

A

Short peptide chains with 1 proximal L-alanine chain and 2 distal D-alanine chains.

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7
Q

Outline the process by which Penicillin inhibits penicillin binding protein.

A

1) PBP binds to peptide side chains and forms cross links with the removal of D alanine from peptide side chains.
2) PBP dissociantes from the cell wall after the cross-links are formed.
3) Penicillin enters the active site of the PBP and reacts with a serine group (a amino acid used in the biosynthesis of proteins).
4) Beta-lactam ring of penicillin is irreversibly opened. Penicillin remains covalent linked to PBP which permanently blocks the active site.

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8
Q

Describe the Pharmacokinetic properties of Penicillin G.

A

Acid Labile, widely distributed, rapid renal excretion.

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9
Q

What is meant by a drug being acid labile?

A

It is easily destroyed in acidic envrionments.

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10
Q

What is the common molecular structure of beta-lactam antibiotics?

A

4 atom ring

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11
Q

By what process do beta lactase enzymes brea Beta-lactam rings?

A

Hydrolysis

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12
Q

What penicillin type is known as ‘The prototype’?

A

Penicillin G

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13
Q

Name a type of acid resistant penicillin.

A

Penicillin V

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14
Q

Name a type of penicillin which is resistant to penicillinase.

A

Methicillin

Oxacillin

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15
Q

Name some broad spectrum penicillins

A

Amoxicillin

Ampicillin

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16
Q

Name some antipseudoma penicillins

A

Aziocillin

Piperacillin

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17
Q

What type of antibiotic is Penicillinase?

A

Beta-lactamase

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18
Q

What is meant by antibiotics having a broad spectrum?

A

They act on a wide range of disease causing bacteria - may be gram-positive or gram-negative.

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19
Q

Describe the resistance of Oxacillin

A

Resistant to Penicilinase

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20
Q

What type of bacteria does Oxacillin have an effect on?

A

Gram-positive only

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21
Q

Describe the spectrum of Oxacillin

A

Narrow

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22
Q

Describe the spectrum of Ampicillin

A

Wide

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23
Q

What the of Bactria does Ampicillin have an effect on?

A

Mainly gram-negatives

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24
Q

What type of Streptococci caused diseases are Penicillins used to treat?

A

Pneumonia, Meningitis, Pharyngitis, endocarditis, rheumatic fever.

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25
Q

What type of infections are caused by Staphylococci and treated by Penicillins?

A

Skin and wound infections

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26
Q

What type of diseases are caused by Costridia and are treated with Penicillin?

A

Tenatus and Gangrene

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27
Q

What type of disease is caused by H.influenzar and is treated by penicillin?

A

Pneumonia

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28
Q

What type of diseases are caused by E.coi and Pseudomonas Enterococci and are treated using Penicillin?

A

Urinary tract infections (acute only).

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29
Q

What are the possible adverse reactions to Penicillin?

A

Tissue toxicity.
Hypersensitivity.
Immediate anaphylaxis.

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30
Q

What is anaphylaxis?

A

An acute allergic reaction to an antigen.

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31
Q

What is the overall purpose of beta-lactam?

A

Inhibits synthesis of the peptidogycan layer in bacterial cell wall.

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32
Q

What is the overall purpose of beta-lactase enzymes?

A

Break the beta-lactam ring open via hydrolysis.

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33
Q

What is Augmentin antibiotic a combination of ?

A

Clavulanic acid and Amoxycillin

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34
Q

In an Augmentin antibiotic, what is the beta-lactam inhibitor?

A

Clavlanic acid

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35
Q

Describe the antibacterial activity of Clavulanic acid

A

Weak

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36
Q

What type of inhibitor is Clavulanic acid on beta-lactam?

A

Competitive and sometimes irreversible.

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37
Q

What is the main purpose of Cephalosporins?

A

Inhibit synthesis of bacterial cell walls.

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38
Q

Which drug do cephalosporins have similar ADME properties to?

A

Penicillins

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39
Q

What are the possible adverse reactions to Cephalosporins?

A

Hypersensitivity
Thrombophlebitis
Nephrotoxicity

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40
Q

What is hypersensitivity?

A

Un-desirable reactions produced by the immune system.

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41
Q

What is thrombphlebitis?

A

Inflammation of the wall of a vein associated with thrombosis.

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42
Q

What is nephrotoxicity?

A

Kidney damage due to the kidney being exposed to a drug or toxin that causes damage.

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43
Q

What is the main benefit of using Cephalosporins over Penicillins?

A

They have a lower incidence of resistance.

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44
Q

How many generations of Cephalosporins exist?

A

4

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45
Q

What causes the different generations of Cephalosporins to be produced?

A

Modifications of side chains at positions 3 and 7 of the ring.

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46
Q

What are 2nd generation Cephalosporins?

A

Methyl group on the beta-lactam ring is removed.

They have similar structure to generate 1 but are more active against gram negative bacteria

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47
Q

What type of bacteria are 2nd generation Cephalosporins most active against?

A

Gram negative bacteria and Haemophilus influenzas.

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48
Q

What are 3rd generation Cephalosporins?

A

R1 and R2 group changes so they become stable without refrigeration.
Increase activity.
Decreased activity in Gram positive Staphylococci.

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49
Q

What are 3rd generation Cephalosorins often used to treat?

A

CNS infections

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50
Q

In wha type of bacteria do 3rd generation Cephalosporins have a reduced effect?

A

Gram postive Staphylococci

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51
Q

What additional feature does 4th generation Cephalosporins have in comparison to the other generations?

A

Quaternary N-methyl Pyrrolidine at R1

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52
Q

Describe the resistance of 4th generation Cephalosporins

A

Highly resistant to beta-lactase

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53
Q

Describe the spectrum of 4th generation Cephalosporins

A

Wide spectrum for both gram positive an gam negative bacteria

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54
Q

Why do 4th generation Cephalosporins have minimal beta-lactamase activity?

A

There is rapid periplasmic penetration and high penicillin binding protein access.

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55
Q

What is the effect of Isoniazid on bacteria

A

Inhibits cell wall (mycolic acid) synthesis

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56
Q

What % of bacterial cell walls is comprised of Mycolic Acid?

A

40

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57
Q

Describe the structure of Mycolic acid

A

Alpha-alkyl and beta-hydroxyl long chain fatty acids.

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58
Q

What is the mycobacterial enzyme?

A

Peroxidase

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59
Q

What does deletion of the peroxidase gene in bacteria cause?

A

Resistance to mycobacterial infections.

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60
Q

What side effects are caused by Isoniazid ?

A

Peripheral neuropathy and other nervous system issues.

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61
Q

What can be used to aid the effects of Isoniazid?

A

Vitamin B6

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62
Q

What is Rifampicin used to treat and how?

A

Used to treat cancer, tuberculosis and leprosy.

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63
Q

How is Rifampicin used to treat Mycobacterium infections?

A

It binds to RNA polymerase and inhibits bacterial RNA synthesis by inhibits the bacterial DNA dependent RNA polymerase

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64
Q

What are the side effects of Riampicin?

A

Hepatoxicity

65
Q

What is hepatoxicity?

A

A substance which can be damaging to the liver cells

66
Q

What effect does Chloramphenicol have as an antibiotic protein synthesis inhibitor ?

A

It binds to the 50s section of the ribosome and inhibits formation of peptide bonds. Affects translation.

67
Q

What effect do Lincosamides have as antibiotic protein synthesis inhibitor?

A

They bind to the 50s section of ribosomes and inhibit the formation of peptide bonds. Affects translation.

68
Q

What effects do Streptomycin have as antibiotic synthesis protein inhibitors?

A

Change the shape of the 30s portion of ribosomes and cause the mRNA code to change and be read differently.

Affects translation

69
Q

What effects do Aminoglycosides have as antibiotic protein synthesis inhibitors?

A

They prevent f-met binding and the formation of the initiation complex during translation.

70
Q

What type of antibiotic is erythromycin?

A

A macrolide

71
Q

When is Erythromycin often used as an antibiotic treatment?

A

When people are allergic to penicillin

72
Q

What treatment is often used for people who are allergic to penicillin ?

A

Erythromycin

73
Q

How does Erythromycin work as an antibiotic inhibitor of protein synthesis?

A

It causes removal of the tRNA molecules and translocation of the peptide tRNA.

74
Q

How does the synthesis of precursors cause antibiotic inhibition?

A

Prevents formation of purine and pyrimidine bases.

75
Q

How do inhibitors of DNA replication act as antibiotic resistors?

A

They prevent the action of bacterial gyrase

76
Q

How do inhibitors of RNA polymerase act as antibiotic inhibitors?

A

They prevent RNA synthesis and have a higher affinity to bacterial RNA polymerises.

77
Q

What are the different classes of antiviral drug treatments used against HIV?

A

Enty Inhibitors

Protease Inhibitors

Nucleoside reverse transcriptase inhibitors and nucleotide reverse transcriptase inhibitors.

Non-nucleoside reverse transcriptase inhibitors.

78
Q

How are entry inhibitors used to treat HIV?

A

They interfere with binding, fusion and entry of HIV to hose cells by blocking one of several targets.

79
Q

How do protease inhibitors work when treating HIV?

A

Inhibit activity of protease

80
Q

How do nucleoside reverse transcriptase inhibitors work to treat HIV?

A

Inhibit reverse transcription by incorporation into newly synthesised viral DNA strands as faulty nucleotides.

81
Q

How are non-nucleoside reverse transcriptase inhibitors used to treat HIV?

A

They inhibit reverse transcriptase by binding to the allosteric site of the enzyme and acting as a non-competitive inhibitor of reverse transcriptase.

82
Q

What is Acyclovir ?

A

A nucleoside reverse transcriptase inhibitor used to treat Herpes and HIV.

83
Q

What is Acyclovir used to treat?

A

Herpes and HIV

84
Q

What causes Acyclovir to be a prodrug?

A

After phosphorylation to acyclovir-GTP, it has a 100x greater affinity for viral polymerase.

85
Q

How does Acyclovir work against Herpes and HIV?

A

Incorporation into viral DNA causes premature chain- termination and prevents viral replication.

86
Q

What effect does Acyclovir have on HIV-1?

A

Its progress is delayed.

87
Q

What are the possible mechanisms of antibiotic resistant?

A

Target site alteration.
Access to target site modification.
Inactivation of antibiotics.
Extrusion.

88
Q

How does target site alteration act as a mechanism of antibiotic resistance?

A

Target site alteration is used to reduce the affinity of the antibiotic without impairing norma cellular function.

89
Q

How does target site alteration of cell walls occur as a method of antibiotic resistance?

A

Penicillin binding proteins shit in the amino acid sequence and reduce the affinity for penicillin.

90
Q

How does target site alteration of protein synthesis occur as a method of antibiotic resistance?

A

The covalent bonding in ribosomes is altered due to changes in the amino acid sequence. This reduces the affinity for Erythromycin and tetreacycline.

91
Q

What effect does access to target side modification have on antibiotic resistance?

A

Affects the ability of an antibiotic to enter the bacterial cell and gain access to the target site.

92
Q

How is the access to the target site of a bacterial cell altered as a mechanism of antibiotic resistance?

A

There are alterations to the composition of the bacterial membrane or cell wall which can reduce permeability for an antibiotic.

93
Q

How is the inactivation of antibiotics caused by effecting cell walls?

A

Occurs as beta-lactamases inactvative penicillin by catalysing lactam ring cleavage.

94
Q

How does inactivation of antibiotics occur due to affecting protein synthesis?

A

Aminoglycoside modifying enzymes and chloramphenicol transferases prevent disruption of protein synthesis by modifying antibiotic structure.

95
Q

What is extrusion in terms of antibiotics?

A

Antibiotic enters bacteria, but rapid expulsion lowers cytoplasmic antibiotic concentration.

96
Q

What is meant by specific drug resistance?

A

Organism resistant to one drug

97
Q

What is multi drug resistance ?

A

Organisms resistant to more than one drug

98
Q

Define Chemotherapy

A

The use of drugs to treat disease.

99
Q

Define Antimicrobial

A

A drug that inhibits growth of microorganisms.

100
Q

Define Antibacterial

A

Substances used to disinfect non-living surfaces.

101
Q

Define antibiotic

A

Class of drugs used to treat bacterial infections by producing a microbe, in small amounts, that will inhibit another microbe.

102
Q

Define anti-fungals

A

A class of drugs used to treat fungal infections.

103
Q

Define antivirals

A

A class of drugs used to treat viral infections

104
Q

In what year did Fleming discover Penicillin?

A

1928

105
Q

Which strain of Penicillin did Fleming initially discover?

A

Peicillium Notatum

106
Q

When were the first clinical trials of Penicillin carried out and by who?

A

1940 by Howard Florey and Ernst Chain

107
Q

In the first treatment with Penicillin, what was used when the dose of Penicillin ran out?

A

The patients urine was purified and re-injected.

108
Q

How are antibiotics classified?

A

By their mechanisms of action, their chemical structure, their spectrum of activity

109
Q

What is meant by the spectrum of an antibiotic ?

A

The different types of microorganism (from gram-positive to gram-negative) that it can act on.

110
Q

What are the possible target sites for antibiotics?

A

Inhibition of cell wall synthesis.

Inhibition of protein synthesis.

Inhibition of nucleic acid replication and transcription.

Injury to the plasma membrane.

Inhibition of synthesis of essential metabolites.

111
Q

What are the desirable antimicrobial properties of an antimicrobial?

A

Selectivity
Broad Spectrum
‘Cidal activity

112
Q

What is ‘cidal activity?

A

Kills bacteria without reliance on the patients immune system.

113
Q

What are the desirable pharmacological properties of an antimicrobial?

A

Non-toxic to the host.

Good tissue distribution.

Low plasma protein binding.

Oral and parenteral dosing forms.

No interference with other drugs.

114
Q

What is meant by the therapeutic index of a drug?

A

The ratio of the toxic dose and the therapeutic dose.

115
Q

Define therapeutic dose of a antibiotic

A

The level of antimicrobial required for clinical treatment of a particular infection.

116
Q

Define toxic dose of a antibiotic

A

The level of antimicrobial at which the antibiotic becomes too toxic for the host.

117
Q

What is meant by antibiotics being bactericidal?

A

Antibiotics that target bacteria cell wall or membrane or interfere with enzymes have bactericidal activity.

118
Q

What are antibiotics that are bacteriostatic?

A

They usually target protein synthesis in bacterial cells.

119
Q

Are bactericidal or bacteriostatic drugs generally more effective?

A

Bactericidal

120
Q

What value is used to determine the effectiveness of an antibiotic?

A

The MIC (Minimum inhibitory Concentration).

121
Q

What is the MIC (Minimum Inhibitory Concentration) of an antibiotic ?

A

The west concentration of an antibiotic that prevents growth of the bacterium.

122
Q

Name factors that affect antibiotic concentration.

A 
Dose
Route of Administration
Absorption
Extent of Protein Binding
Rate of metabolism
Rate of excretion
123
Q

What concentration must an antibiotic have in the body to be effective?

A

Must have a concentration at the site of infection that is above the MIC of the bacterium it is targeting.

124
Q

In what year was antibiotic inhibition of bacterial cell wall synthesis discovered?

A

1947

125
Q

Outline the mechanism for antibiotic inhibition of bacterial cell wall synthesis.

A

Selectively acts on membranes rich in phosphatidlethanolamine.

126
Q

What type of bacteria does the method of antibiotic inhibition of cell wall synthesis work on?

A

Works on many gram-negative rods but is ineffective against gram-positives.

127
Q

Describe the effectiveness of antibiotics crossing cell membranes.

A

Very poor

128
Q

Where are antibiotics excreted in the body?

A

Via the kidneys

129
Q

Describe the distribution properties of antibiotics

A

Don’t distribute very well

130
Q

What locations are antibiotics which inhibit bacterial cell wall synthesis usually used in?

A

Used in topical locations

131
Q

What are the adverse reactions of antibiotics which inhibit cell wall synthesis?

A

Nephrotoxicity and Neurotoxicity

132
Q

Outline the mechanism of action of Polymyxin B

A

After binding Lipopolysaccharides in the outer membrane of gram-negative bacteria, Polymxins disrupt both the outer and inner membranes of bacteria.

133
Q

Why is the hydrophobic tail of Polymyxin B important to inhibiting cell wall synthesis of bacterial cells?

A

Is causes membrane damage with a detergent-like model of action.

134
Q

Which is the cell wall an ideal target for chemotherapy?

A

Cell walls are present in bacterial and fungal cells but not in mammalian cells.

135
Q

Where does peptidoglycan precursor formation for bacterial cell wall production occur ?

A

Inside the cell

136
Q

What inhibitor is used to block peptidoglycan precursor formation when forming bacterial cell walls?

A

Cycloserine

137
Q

Where in a bacterial cell does transport and peptidoglycan formation occur?

A

Cell membrane

138
Q

What inhibitor is used to inhibit transport and peptidoglycan formation in bacterial cells?

A

Bacitracin Vancomycin

139
Q

Where in bacterial cells does cross linking of peptidoglycan chains occur?

A

Outside the cell

140
Q

What inhibitor is used to inhibit the cross linking of peptidoglycan chains in bacterial cell walls?

A

Penicillins Cephalosporins

141
Q

What are cycloserine structurally similar to?

A

D-alanine

142
Q

In what type of organisms is cycloserine found?

A

Gram positive peptidoglycan tetra peptide

143
Q

What are the clinical uses Cycloserine?

A

Used in tuberculosis treatment.

144
Q

What is the purpose of Bacitracin in bacterial cells?

A

It is requires as a carrier during peptidoglycan synthesis.

145
Q

How does Bacitracin create a carrier for bacteria?

A

Inhibits the dephosphorylation of udecaprenyl phosphate to produce a carrier.

146
Q

Outline the mechanism by which Vancomycin inhibits cell wall production in bacterial cells.

A

It is a glycopeptide which binds with high affinity D-ala-D-ala terminus of the cell wall precursor units.
This prevents cross-linking and disrupts peptidoglycan synthesis.

147
Q

What type of molecule is Vancomycin?

A

Glycopeptide

148
Q

Describe the spectrum of Vancomycin

A

Narrow

149
Q

What are the side effects of Vancomycin as an antibiotic?

A

It can be Ototoxic

150
Q

What is Ototoxicity?

A

Toxic to the ear

151
Q

What are the clinical uses of Vancomycin?

A

Used to treat MRSA

152
Q

How does Vancomycin affect sensitive bacteria?

A

It binds to 2 D-ala residues on the ends of peptide chains. This prevents the peptide chains from interacting with cell wall cross-linking enzymes. The cell wall strands are synthesises but not cross linked, so the cell walls fall apart.

153
Q

How does Vancomycin affect resistant bacteria?

A

Vancomycin cannot bind D-lactate residues, peptide chains interact with cell wall cross-linking enzymes and form stable cross-links.

154
Q

What is the structure of beta-lactam?

A

A 4 membered cyclic amide ring.

155
Q

What are beta-lactam’s attached to a 6 membered ring called?

A

Cephalosporins

156
Q

What are beta-lactam’s attached to a 5 membered ring called?

A

Penicillins or Penems

157
Q

What are beta-lactams attached to no rings called?

A

Monobactams

158
Q

Why are penicillin binding proteins essential for cellular survival and growth in bacteria?

A

They create cross links in cell walls.

159
Q

How can Penicillin binding proteins be identified?

A

By the binding of radioactive benzylpenicillin.

Principles Of Pharmacology (11 decks)

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