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Antiparasitic-Table 1 Flashcards

1
Q

What is the definition of symbiosis?

A

relationship between two species for the purpose of obtaining food or habitat

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2
Q

What is parasitism?

A

type of symbiotic relationship in which one species, the host, is injured by the activities of the other

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3
Q

What 2 things is injury dependent on?

A

Parasite load and immunologic competence of host

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4
Q

What are the protozoal diseases?

A 
Malaria
Giardiasis (intestinal)
Amebiasis (intestinal)
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5
Q

What are the Helminth diseases?

A

Necatoriasis (hookworm)
Enterobiasis (pinworm)
Ascariasis (roundworm)
Neurocysticercosis (tapeworm)

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6
Q

What are the 3 major potential targets for antiparasitic chemotherapy?

A
  • Unique enzymes found only in the parasite
  • Enzymes found in the both host and parasite but indispensible only to the parasite
  • Common biochemical functions found in both parasite and host but with different pharmacologic properties
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7
Q

What are the protozoal tx for malaria?

A
  • Chloroquine, hydroxychloroquine, quinine, Mefloquine, artemisinin, pyrimethemine
  • Primaquine
  • Doxycycline
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8
Q

What is the protozoal tx for giardiasis?

A

Metronidazole

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9
Q

What is the protozoal tx for amebiasis?

A
  • Paromomycin
  • Diloxamide
  • Metronidazole
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10
Q

What drugs are effective against malaria in the tissue? RBC? Gametocytes?

A
  • -primaquine, doxycycline
  • -chloroquine, quinine, mefloquine
  • -primaquine
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11
Q

What is the chloroquine chemoprophylaxis for malaria?

A 
Chloroquine 500mg (300mg of base) po weekly       OR
Hydroxychloroquine 400mg (310mg of base) po weekly
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12
Q

When is the chloroquine chemoprophylaxis used?

A

in areas where P. falciparum is susceptible

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13
Q

What is the chloroquine chemoprophylaxis active against?

A

erythrocytic forms of malaria

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14
Q

When should tx with the chloroquine chemoprophylaxis be initiated and how long should it be continued?

A

1 week before exposure and 4 weeks after leaving endemic area

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15
Q

What is the MOA the chloroquine chemoprophylaxis?

A

causes membrane lysis of both parasite and RBC

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16
Q

What are the ADRs of cholorquine?

A

Dyspepsia, vertigo, insomnia, retinal toxicity (long duration)
Discoloration of nail beds and mucous membranes with chronic administration

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17
Q

Is chloroquine safe in pregnancy?

A

Yes but not hydroxychloroquine

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18
Q

What is the mefloquine prophylaxis? When is it used?

A

Mefloquine 250mg po weekly

Used in areas of chloroquine resistance

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19
Q

What forms of malaria is mefloquine active against?

A

erythrocytic forms of malaria

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20
Q

What should the mefloquine prophylaxis be initiaited and how long should it be continued?

A

1 week before exposure (2-3 weeks is preferable) and continue for 4 weeks after leaving malaria-endemic area

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21
Q

What are the ADRs of mefloquine?

A

dyspepsia, vertigo, insomnia, vivid dreams, SZs, depression, suicidal ideation

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22
Q

What pts should you not prescribe mefloquine to?

A

Recent HX of depression, GAD, schizophrenia, psychosis or convulsions
Performing activities requiring fine coordination and spatial discrimination (eg. Pilots, machine operators)

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23
Q

Is mefloquine safe in preggos?

A

Yes

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24
Q

What is the atovaquone and proguanil prophylaxis?

A

250mg atovaquone/100mg proguanil: 1 tab po daily

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25
Q

When should atovaquone and proguanil prophylaxis be initiated and how long should it be continued?

A

1 day prior and continue for 1 week after leaving malaria-endemic area

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26
Q

What are the ADRs of atovaquone and proguanil ?

A

well tolerated, abdominal pain, N/V, HA, increased LFTs

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27
Q

When is atovaquone and proguanil CI?

A 
Pregnant women (no data)
Patients with severe renal dysfunction (Clcr
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28
Q

What is the doxycycline chemoprophylaxis?

A

100mg po daily (very inexpensive)

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29
Q

When should doxycycline chemoprophylaxis be initiated and how long should it be continued?

A

1 day prior to exposure and continue for 4 weeks after leaving malaria-endemic area

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30
Q

What is doxy effective against?

A

erythrocytic forms of malaria

Not effective as sole agent in treatment

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31
Q

What are the ADRs of doxy?

A

dyspepsia and esophagitis, vaginal candidiasis, photosensitivity

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32
Q

When is doxy CI?

A

Pregnant women

Children

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33
Q

What is the tx of malaria guided by?

A
  • Infecting species and drug susceptibility determined by geographic area
  • Patient status
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34
Q

Which malarial organisms have reported resistance?

A

P. falciparum and P. vivax

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35
Q

Which malarial organism can cause rapidly progressive severe illness or death?

A

P. falciparum

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36
Q

Which organisms have hypnozoite forms that may remain dormant in the liver and need tx?

A

P. ovale and P. vivax

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37
Q

What Is the tx for uncomplicated adult malaria that is chloroquine sensitive?

A

Chloroquine-sensitive
–Chloroquine (Blood Schizontocide)
–1000mg followed by 500mg 6hr later, then again at day 2 and 3
OR
–Hydroxychloroquine
–800mg followed by 400mg 6hr later, then again at day 2 and 3

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38
Q

How is P. vivax or P. ovale malaria tx in uncomplicated adults?

A

Above and Add primaquine 30mg po daily x 14 days (avoid in G6PD deficiency)

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39
Q

What does primaquine do?

A

Tissue Schizonticide—Eradicates primary exoerythrocytic forms of P. falciparum and P. vivax and secondary exoerythrocytic forms of recurring P. vivax and P. ovale

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40
Q

When is primaquine not effective?

A

Against the erythrocytic stage…cant use as monotherapy

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41
Q

What are the ADRs of primaquine?

A
  • Well tolerated = GI and HA most common
  • Rare = agranulocytosis and cardiac arrhythmias
  • G6PD deficiency => hemolysis
    - –Patients should be tested before given
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42
Q

What is the tx for uncomplicated malaria in adults with resistance?

A 
Mefloquine
750mg po x 1 then 500mg 6-12hrs later
         OR
Atovaquone-proguanil
4 tabs po daily x 3 days
         OR
Quinine + Doxycycline
Quinine 650mg TID x 3-7 days
Doxycycline 100mg BID x 7 days
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43
Q

What is quinine?

A

A blood schizonticide active against all 4 species of plasmodium

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44
Q

What is the MOA of quinine?

A

interferes with heme polymerization resulting in death

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45
Q

What are the ADRs of quinine?

A
  • Cinchonism = tinnitus, HA, dizziness, visual disturbances, nausea (reversible)
  • Hypersensitivity and blood dyscrasias (hemolytic anemia)
  • Fetotoxic- no preggos
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46
Q

When is quinine used?

A

Reserved for severe infestations and for strains resistant to chloroquine

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47
Q

What are the quinine drug interactions?

A

Potentiates neuromuscular blocking agents
Increases digoxin level
Decreased absorption with Al antacids

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48
Q

What is the definition of severe malaria?

A 
Impaired consciousness/coma/convulsions
Severe normocytic anemia
Renal failure
Pulmonary edema
ARDS
Circulatory shock
Spontaneous bleeding
Jaundice
High parasitemia (>5%)
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49
Q

What organism typically causes severe malaria?

A

P. falciparum

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50
Q

What is the tx for severe malaria?

A

Quinidine gluconate 600mg IV q12H
PLUS
Doxycycline 100mg IV q12H x 3-7 days

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51
Q

What is the resolution time for severe tx?

A

Fever should break within the first 48 hours and blood should clear of parasites within 5 days

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52
Q

Does malarial infection produce immunity?

A

NO

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53
Q

What is artemisinin?

A

A blood schizonticide used to tx severe multidrug resistant P. falciparum

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54
Q

What is the MOA of artemisinin?

A

free radical production within food vacuole following cleavage of drug’s endoperoxide bridge by heme iron in RBC
Covalently binds and damages malarial proteins

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55
Q

How is artemisinin distributed?

A

PO,IV, rectal

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56
Q

What are the ADRs of artemisinin?

A

Overall safe, N/V/D

High doses neurotoxic and QT prolongation

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57
Q

What is pyrimethamine?

A

Antifolate agent for blood schizonticide and sporontocide

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58
Q

What is pyrimethamine effective against?

A

P. faciparum

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59
Q

What are the ADRs of pyrimethamine?

A

Megaloblastic anemia

  • –Folic acid replacement
  • –Reverse with leucovorin
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60
Q

What is the first line tx for Giardia in people >/= 8 years old?

A

metronidazole (Flagyl) 250mg po TID x 7 days

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61
Q

What are the ADRs of metro?

A

abdominal discomfort, N/V, metallic taste, disulfiram rxn with ETOH

62
Q

What is an alternative therapy for giardia?

A

Nitazoxanide 500mg po BID x 3 days

63
Q

What are the ADRs of Nitazoxanide?

A

abdominal pain, N/V/D, HA

64
Q

What does the drug tx for amebiasis depend on?

A

Clinical presentation! This depends mainly on location
Intestinal= asymptomatic, dysentery, or colitis
Extraintestinal= primaryily liver abscess

65
Q

How are asymptomatic patients tx for amebiasis?

A

Tx with luminal agents only- non absorbable agents

66
Q

How are all symptomatic patients tx?

A

With a luminal agent plus a tissue amebicide

67
Q

What are the drug choices for asymptomatic or luminal amebiasis?

A

Paromomycin 500mg TID x 7 days- use if preggo

Diloxamide 500mg TID x 10 days

68
Q

What is the tx for severe intestinal dz or liver abscess?

A

Aspirate and drain

The metro 750mg po TID x 10 days followed by luminal course then reassess the abscess with imaging 3 mo later

69
Q

When are luminal agents effective?

A

To tx the asymptomatic colonization state or following tx of invasive dz

70
Q

What are the luminal amebicides?

A

Iodoquinol, Diloxanide, Paromomycin

71
Q

What is iodoquinol effective against?

A

E. histolytica luminal trophozoites and cyst forms only

72
Q

What are the ADRs of iodoquinol?

A

GI most common (diarrhea)

Optic neuritis, optic nerve atrophy (rare)

73
Q

How long does a pt need to be tx with iodoquinol?

A

650mg po TID x 20 days

74
Q

Pts intoletant to what should not receive iodoquinol. Why?

A

IODINE- drug molecule contains iodine, nIncreases body iodine content which may persist for months => mild thyroid enlargement

75
Q

What are signs of iodine toxicity to look for in pts taking iodoquinol?

A

Itching, rash, and fever

76
Q

What is diloxanide used to tx?

A

asymptomatic shedders of cysts; not available in US or Canada

77
Q

What are the ADRs of diloxanide?

A

Flatulence, dry mouth, pruritis, urticaria

78
Q

When is diolxanide CI?

A

Preggo and

79
Q

What is paromomycin?

A

Aminoglycoside antibiotic

80
Q

How does paromomycin work?

A

cell membrane leakage

decreases normal flora which is source of food for amebas

81
Q

What are the ADRs of paromoycin?

A

GI distress and diarrhea

82
Q

What is the mixed Amebicide?

A

metronidazole

83
Q

When is metro the DOC?

A

For extraluminal amebiasis- kills tophozoites but not cysts

84
Q

What is the MOA of metro?

A

nitro group of metronidazole serves as electron acceptor, forming reduced cytotoxic cmpd that bind proteins and DNAdeath

85
Q

When should metro be adjusted?

A

In severe liver dz

86
Q

What is the regimen for mild- mod dysentery?

A

flagyl + paromomycin or iodoquinol to clear cysts

87
Q

What is the regimine for severe or extraintestinal infection?

A

flagyl + paromomycin

88
Q

What are the ADRs of metro…againt?

A

Most common = nausea, HA, paresthesias, metallic taste
–GI side effects decreased by giving with food
–CNS side effects include paresthesias
Disulfiram-like reaction
—May cause N,V, flushing if alcohol is ingested during therapy- most unpleasant. I do not recommend tequila and metro!

89
Q

What are the systemic/tissue amebicides?

A

Chloroquine, emetine, and dehydroemetine

90
Q

When is chloroquine used in amebiasis?

A

in combo with metronidazole and diloxanide furoate to tx and prevent amebic liver abscesses

91
Q

When are emetine and dehydroemetine used?

A

to treat liver abscesses unresponsive to flagyl

92
Q

How long is the duration of tx for emetine?

A

Limited to 10 days d/t toxicity- dehydroeme is less toxic

93
Q

How long is the half life of emetine?

A

5 day, 1 IM injection lasts one month

94
Q

What are the ADRS of emetine?

A

Injection site pain, transient nausea, neuromuscular weakness, dizziness, rash, cardiotoxicity- arrhythmias, CHF

95
Q

What worms are parasites?

A

Necatoriasis (hookworm)
Enterobiasis (pinworm)
Ascariasis (roundworm)
Neurocysticercosis (tapeworm)

96
Q

What do anthelmintic drugs need to do in order to be effective?

A

Penetrate the cuticle of the worm

Or gain access to its alimentary tract

97
Q

How do anthelmintic drugs work?

A

Damaging or killing the worm directly.
Paralysing the worm
Damaging the cuticle of the worm so that host defences, such as digestion and immune rejection, can work.
Interfering w/worm metabolism.

98
Q

What are the anthelmintic drugs?

A

Mebendazole

Albendazole

99
Q

What is the tx for Enterobiasis (pinworm)?

A

Mebendazole 100mg x 1, may repeat in 14 days

For all persons > 2 years

100
Q

What is the alternative tx for pinworm?

A

Albendazole 400mg x 1, repeat in 14 days

For all persons > 2 years

101
Q

What re the ADRs for Albendazole?

A

abdominal pain, N/V, Stevens-Johnson syndrome, hematologic effects (pancytopenia, thrombocytopenia, leukopenia, aplastic anemia), hepatotoxicity

102
Q

How is necatoriasis (hookworm) tx?

A

Mebendazole 100mg po BID x 3 days
OR
Albendazole 400mg po x 1
(For all persons > 2 years)

103
Q

How is ascariasis (roundworm) tx?

A

Mebendazole 100mg po BID x 3 days
OR
Albendazole 400mg po x 1
For all persons > 2 years…if there is a severe obstruction surgery is needed

104
Q

Why is it important to have caution when tx neurocysticercosis ( tapeworm)?

A

Sudden destruction of parasites may trigger inflammatory response and seizures

105
Q

Does elimination of the parasite in tapeworm mean there will be neuro improvement?

106
Q

What are the options for tx tapeworm?

A

Surgery
Anticonvulsants
Albendazole 400mg BID +/- dexamethasone 6mg daily for 8-30 days

107
Q

What is mebendazole?

A

Broad spectrum antihelminthic

108
Q

How is mebendazole prescribed?

A

100mg x1 and repeat in 2 weeks

109
Q

How does menendazole work?

A

Irreversibly inhibits glucose uptake in susceptible nematodes; also interferes with assembly of microtubules

110
Q

What is mebendazole used to tx?

A

Whipworm, roundworm, hookworms, pinworms

111
Q

How is the efficacy of mebendazole increased?

A

By chewing tablets- poorly absorbed

112
Q

What are the most common ADRs of mebendazole?

A

Abdominal discomfort and diarrhea

113
Q

When is mebendazole CI?

A

pregnant patients in first trimester, in children

114
Q

What is albendazole?

A

Broad spec antihelminthic that enters the CNS and cysts and is larvicidal

115
Q

How is albendazole administered?

A

On an empty stomach for luminal parasites and with a fatty meal for extraluminal dz

116
Q

Short term albendazole has few ADRS( hA/N). what is the risk with high doses or long term therapy?

A

Hepatotoxicity, pancytopenia, inflammation in CNS HA, voniting, hyperthermia, mental changes, convulsion

117
Q

What should you do if giving high or long doses of albendazole to your pt?

A

baseline LFT’s and a CBC every 2 weeks

118
Q

When is albendazole CI?

A

pregnant patients in first trimester, in children

119
Q

What is the MOA of niclosamide?

A

Inhibition of mitochondrial anaerobic phosphorylation of ADP no energy

120
Q

What is the ROA of niclosamide?

A

PO- little is absorbed from the GI

121
Q

When is niclosamide indicated?

A

Tapeworm infestation- Cestodes

122
Q

What are the ADRs of niclosamine?

A

Very little since not absorbed from GI

Some mild GI disturbance

123
Q

What do you need to give your pt prior to niclosamide?

A

Laxatives to purge the OVA

124
Q

What is pyrantel pamoate used for?

A

Roundworms, pinworms, hookworms

Poorly absorbed and used only for intestinal parasites

125
Q

How does pyrantel pamoate work?

A

Acts as a depolarizing neuromuscular blocker inducing worm paralysis

126
Q

What are the ADRs of pyrantel pamoate?

A

mild, infrequent and transient = most common = GI (N/V/D)

127
Q

Is pyrantel pamoate available OTC?

A

Yes as Pin-Rid or Pin-X

128
Q

What is pyrantel pamoate not active against?

A

Migratory stage and ova

129
Q

What are the CI to pyrantel pamoate?

A

pregnant patients in first trimester, in children

130
Q

What is the MOA of praziquantel?

A

Increases cell membrane permeability to calcium causing paralysis, dislodgement and death

131
Q

When is praziquantel effective?

A

wide variety of nematode, trematode and cestode infections

132
Q

How is praziquantel absorbed and excreted?

A

PO and urine/bile

133
Q

What should you admin to a pt with tapeworms following praziquantel?

A

of a purgative- dead worms may release embryos that may mature and become infectious

134
Q

How long should praziquantel therapy be prescribed for?

135
Q

What should your pts be educated about when taking praziquantel?

A

Should be taken after meals with full glass of water and never chewed

136
Q

What are the most frequent ADRs of praxiquantel?

A

drowsiness, dizziness, HA, GI upset – appear within 24 hours and go away in the next 24-48

137
Q

Which drugs may interact with praziquantel and cause tx failure?

A

anticonvulsants

138
Q

Should praziquantel be taken when preggo?

139
Q

What is the MOA of thiabendazole?

A

affects microtubular aggregation

140
Q

What is thiabendazole active against?

A

threadworms, cutaneous larva migrans and early stages of trichinosis (nematodes)

141
Q

What are the ADRs of thiabendazole?

A

N/V, anorexia, dizziness

Erythema multiforme, SJSfatalities

142
Q

When is thiabendazole CI?

143
Q

What is diethylcarbamazine used to tx?

A

filariasis (elephantiasis) by immobilizing microfilariae thus susceptible to host defenses
Combine with abendazole

144
Q

What are the ADRs of diethylcarbamazine caused by?

A

host rxn to killed organisms
Severity related to parasite load…fever, malaise, rash, myalgias, arthralgias, HA, leukocytosis tx with steroids, antihistamines

145
Q

What is the causative organism in onchocerciasis? What carries it?

A

Onchocerca volvulus
Black fly
Microfiliaria(offspring) cause the actual dz

146
Q

What are the symptoms of onchocerciasis ( river blindness)?

A

Severe itching, subcutaneous nodules, ocular lesions often resulting in blindness (blindness due to years of assault)

147
Q

What is the tx for river blindness?

A

Ivermectin- can also use against scabies and threadworm

148
Q

How often should ivermectin be used?

A

Tx once yearly until the adult worms are dead

149
Q

What is the ADR of ivermectin?

A

Allergic/inflammatory response: Mazotti-like reaction (fever, HA, dizziness, somnolence, hypotension, arthralgia, edema, lymphadenopathy, ocular damage, rash, pruritis, synovitis)

150
Q

When is ivermectin CI?

Pharm3- fixed (12 decks)

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