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CNS > Pharma 9: Infections of CNS > Flashcards

Pharma 9: Infections of CNS Flashcards

1
Q

The effect of inflammation on the permeability of BBB

A

Bacterial meningitis, encephalitis→ inflammation→disrupt BBB integrity→ allow substances into the brain which normally would not have been able to penetrate

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2
Q

Penicillin’s access to brain normally and in bacterial meningitis

A

NORMALLY→ must be given IT

Meningitis→IV

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3
Q

98% of low mw drugs

A

((<400Da)) DO NOT CROSS BBB

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4
Q

Large mw drugs

A

CANT ENTER BBB

these include anticancer,bacterial, monoclonal ab, gene therapies

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5
Q

To cross BBB drug must be

A
  1. lipid soluble
  2. mw <400Da
  3. <8-10 hydrogen bonds with solvents in water
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6
Q

Relationship between lipid solubility and accessibility to BBB

A

NOT LINEAR because:

if highly lipid soluble→ it will be better distributed peripherally→less for CNS

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7
Q

Which lipohilic drugs cross BBB

A

SMALL

antidepressants, anxiolytic/hypnotics, antiepileptics, opioids (except the ones that target GI)

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8
Q

Glucose GLUT 1

A

D-glucose

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9
Q

Monocarboxylic acid MCT1

A

L-lactic acid

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10
Q

Neutral amino acid LAT1

A

L-phenylalanine

L-DOPA, Gabapentin→high affinity for BBB carrier mediated transporters

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11
Q

Basic amino acid CAT1

A

L-arginine

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12
Q

Purine nucleoside CNT2

A

Adenosine

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13
Q

Principles of improving CNS drug delivery

A
  • Enhance BBB permeability
  • Chemical alterations to drug
  • Transcranial drug delivery→intracerebral polymer implants
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14
Q

Method of enhancing BBB permeability

A

chemically induced osmotic sock

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15
Q

Methods of chemically inducing osmotic shock

A
  1. Hyperosmolar MANNITOL infusion in IC artery
  2. Vasocative agents transiently increase BBB permeability like histamine (plasma albumin enters as well→ASTROGLIOSIS→not used clinically)
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16
Q

Chemical alterations made to the drug

A

Prodrug→activated in CNS eg. LEVODOPA

Lipidization→make drug more lipid soluble→downside: loss of pharmacological activity

Imitate endogenous ligands→transported by natural receptors, transporters and carries across BBB eg. LEVODOPA

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17
Q

Transcranial drug delivery process

A
  1. open cranium
  2. insert intracerebral polymer implant (GLIADEL) (up to 8) which are loaded with CARMUSTINE→anticancer
  3. The drug is released as the wafer is slowly degraded
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18
Q

How does rabies reach the brain

A

thru the nerves

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19
Q

Principles of treatment of CNS infections

A
  1. eliminate the microorganism with the use of a drug toxic to the microorganism administered at a sufficient concentration at the site
  2. treat responses secondary to the infection ie treat seizures with antiep and inflammation with gc
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20
Q

treatment of abscess

A

surgical and pharmacological

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21
Q

drugs and their concentrations in CSF

A 
Penicillin→ 5%
Vancomycin→ 10%
Ampicillin→15%
Cefotaxime→15%
Gentamycin→20%
Chloramphenicol→30%
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22
Q

direct administration of gentamycin

A

very risky

directly injected into ventricles with gram -ve→ increased mortality

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23
Q

Acyclovir MOA

A

Synthetic nucleoside analog

Guanosine’→monophosphorylated by viral thymidine kinsae→incorporated into viral dna→chain termination→inhibit dna replication

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24
Q

nuceloside analogues

A 
acyclovir
valacyclovir
peniclovir
famciclovir
ganciclovir
cidofovir
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25
Q

ACV uses

A

prophylaxis and treatment of HSV and VZV infections even immunocompromised patients

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26
Q

ACV administration

A

IV/orally→cross BBB via nucleoside transporter

topically

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27
Q

ACV side effects

A

well tolerated
BUT

nephrotoxic and neurotoxic (dose adjeusted in pt with renal failure ad drug excreted by kidneys) reversible after discontinuation

28
Q

ACV administration

A

SLOW IV

fast iv bolus→crystalluria and elevated serum creatinine→ACV crystals→obstruct renal tubular lumen

29
Q

Ara-A/foscarnet use

A

acyclovir resistant HSV-1 encephalitis

30
Q

Sorivudine use

A

VZV infections

31
Q

Ganciclovir use

A

CMV encephalitis

32
Q

Caution with gancyclovir

A

Bone marrow toxicity

Excreted by kidney→check renal function

33
Q

In HIV

A

treat according to etiology

34
Q

Bacterial meningitis according to age

A

<1 month→gram -ve and group B
1 month - 15 years→ H. influ, N.meningiditis, S. pneumo

.15yrs→N. menin, S pneumo, staph

35
Q 
Antibiotic therapy for:
 S pneumo
 streptooccus groups A and B
 L. monocytogens
 N. meningiditis,
A

penicillin G

36
Q

B lactamase -ve H influenza

A

Ampicillin

37
Q

B lactamase +ve H influenza

A

Cefotaxime

38
Q

E. coli
Kliebsella
Proteus

A

Cefotaxime/Ceftriaxone with Gentamycin

39
Q

Penicillins, Cephalosprins

classification

A

B lactams

40
Q

Penicillins, Cephalosporins

MOA

A

BACTERICIDAL (MAINLY)

inhibit peptidoglycan cross linking by binding to PBP→bacterial cell wall lysis

41
Q

Penicillins

ADMIN

A

Orally or parentally depends on stability of acid

42
Q

Penicillins

distribution

A

Throughout body tissues and fluids

43
Q

Penetration of penicillins across BBB

A

once meninges inflamed→readily penetrates to reach therapeutic retractions at CSF

44
Q

Penicllins

elimination

A

by kidney

primarily by tubular secretion

45
Q

Penicillins side effects

A

HYPERSENSITIVITY→benign rash to anaphylaxis

N/V diarrhea

CROSS ALLERGY WITH OTHER PENICILLINS or CEPHALOSPORINS

46
Q

Cephalosporin

A

Cefatoxime

47
Q

Cephalosporins similar to penicillins in terms of

A

MOA, chemistry, toxicity

48
Q

Cephalosporins advantage over penicillins

A

more resistant to b lactamases→broader spectrum

49
Q

Cephalosporins are ineffective against

A

Enterococci

L monocytogenes

50
Q

Aminoglycosides

A

Gentamycin

51
Q

Gentamycin MOA

A

Bactericidal

binds IRReversibly to 30s subunit→inhibit bacterial protein synthesis

52
Q

Gentamycin adminstered

A

IV INFUSION OVER 15-30 MINUTES BECAUSE IT ISNT ABSORBED ORALLY

53
Q

Gentamycin CNS penetration

A

Poor but effective

54
Q

Gentamycin elimination

A

glomerular filtration

55
Q

Gentamycin side effects

A

LOW TI

nephrotoxicity, ototoxicity, NM blockade

56
Q

Fungal CNS infections are common in?

A

Immunocompromised patients eg AIDS

57
Q

Similarity between fungal infections and M. TB

A

inhaled to affect lungs and sometimes CNS

58
Q

Amphoterecin B use

A

life threatening fungal infection such as histoplasmosis, coccidiomycosis

59
Q

Amphoterecin B MOA

A

Binds ergosterol of cell wall→ forms pores in cell membrane→hydrophilic core forms and ion channel→unregulated leakage of ions and metabolites

60
Q

Amphoterecin B adminstration

A

IV→reaches therapeutic levels in CSF with a risk of toxicity

61
Q

Amphoterecin side effects

A

Nephrotoxicity→sever kidney damage

62
Q

Preventing amphoterecin B toxicity

A

giver water IV and monitor kidney function

63
Q

Which form of Amphoterecin B has less side effects

A

Lipid formulations like liposomal amphoterecin B

64
Q

Flucytosine MOA

A

inhibits fungal DNA synthesis by disrupting function of RNA in protein synthesis

65
Q

Amphoterecin B and flucytosine synergic action

A

Amphoterecin B makes the cell more permeable to flucytocsin→effective against C. neoformans meningitis

66
Q

Flucytosine side effects

A

RARE

gi disturbances
anemia
neutropenia
thrombocytopenia

USUALLY causes the drug to be discontinued

CNS (28 decks)

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