Antiparasitic-Table 1 Flashcards
(150 cards)
1
Q
What is the definition of symbiosis?
A
relationship between two species for the purpose of obtaining food or habitat
2
Q
What is parasitism?
A
type of symbiotic relationship in which one species, the host, is injured by the activities of the other
3
Q
What 2 things is injury dependent on?
A
Parasite load and immunologic competence of host
4
Q
What are the protozoal diseases?
A
Malaria Giardiasis (intestinal) Amebiasis (intestinal)
5
Q
What are the Helminth diseases?
A
Necatoriasis (hookworm)
Enterobiasis (pinworm)
Ascariasis (roundworm)
Neurocysticercosis (tapeworm)
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
7
Q
What are the protozoal tx for malaria?
A
- Chloroquine, hydroxychloroquine, quinine, Mefloquine, artemisinin, pyrimethemine
- Primaquine
- Doxycycline
8
Q
What is the protozoal tx for giardiasis?
A
Metronidazole
9
Q
What is the protozoal tx for amebiasis?
A
- Paromomycin
- Diloxamide
- Metronidazole
10
Q
What drugs are effective against malaria in the tissue? RBC? Gametocytes?
A
- -primaquine, doxycycline
- -chloroquine, quinine, mefloquine
- -primaquine
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
12
Q
When is the chloroquine chemoprophylaxis used?
A
in areas where P. falciparum is susceptible
13
Q
What is the chloroquine chemoprophylaxis active against?
A
erythrocytic forms of malaria
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
15
Q
What is the MOA the chloroquine chemoprophylaxis?
A
causes membrane lysis of both parasite and RBC
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
17
Q
Is chloroquine safe in pregnancy?
A
Yes but not hydroxychloroquine
18
Q
What is the mefloquine prophylaxis? When is it used?
A
Mefloquine 250mg po weekly
Used in areas of chloroquine resistance
19
Q
What forms of malaria is mefloquine active against?
A
erythrocytic forms of malaria
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
21
Q
What are the ADRs of mefloquine?
A
dyspepsia, vertigo, insomnia, vivid dreams, SZs, depression, suicidal ideation
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)
23
Q
Is mefloquine safe in preggos?
A
Yes
24
Q
What is the atovaquone and proguanil prophylaxis?
A
250mg atovaquone/100mg proguanil: 1 tab po daily
25
When should atovaquone and proguanil prophylaxis be initiated and how long should it be continued?
1 day prior and continue for 1 week after leaving malaria-endemic area
26
What are the ADRs of atovaquone and proguanil ?
well tolerated, abdominal pain, N/V, HA, increased LFTs
27
When is atovaquone and proguanil CI?
```
Pregnant women (no data)
Patients with severe renal dysfunction (Clcr
```
28
What is the doxycycline chemoprophylaxis?
100mg po daily (very inexpensive)
29
When should doxycycline chemoprophylaxis be initiated and how long should it be continued?
1 day prior to exposure and continue for 4 weeks after leaving malaria-endemic area
30
What is doxy effective against?
erythrocytic forms of malaria
| Not effective as sole agent in treatment
31
What are the ADRs of doxy?
dyspepsia and esophagitis, vaginal candidiasis, photosensitivity
32
When is doxy CI?
Pregnant women
| Children
33
What is the tx of malaria guided by?
- Infecting species and drug susceptibility determined by geographic area
- Patient status
34
Which malarial organisms have reported resistance?
P. falciparum and P. vivax
35
Which malarial organism can cause rapidly progressive severe illness or death?
P. falciparum
36
Which organisms have hypnozoite forms that may remain dormant in the liver and need tx?
P. ovale and P. vivax
37
What Is the tx for uncomplicated adult malaria that is chloroquine sensitive?
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
38
How is P. vivax or P. ovale malaria tx in uncomplicated adults?
Above and Add primaquine 30mg po daily x 14 days (avoid in G6PD deficiency)
39
What does primaquine do?
Tissue Schizonticide---Eradicates primary exoerythrocytic forms of P. falciparum and P. vivax and secondary exoerythrocytic forms of recurring P. vivax and P. ovale
40
When is primaquine not effective?
Against the erythrocytic stage…cant use as monotherapy
41
What are the ADRs of primaquine?
- Well tolerated = GI and HA most common
- Rare = agranulocytosis and cardiac arrhythmias
- G6PD deficiency => hemolysis
- --Patients should be tested before given
42
What is the tx for uncomplicated malaria in adults with resistance?
```
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
```
43
What is quinine?
A blood schizonticide active against all 4 species of plasmodium
44
What is the MOA of quinine?
interferes with heme polymerization resulting in death
45
What are the ADRs of quinine?
- Cinchonism = tinnitus, HA, dizziness, visual disturbances, nausea (reversible)
- Hypersensitivity and blood dyscrasias (hemolytic anemia)
- Fetotoxic- no preggos
46
When is quinine used?
Reserved for severe infestations and for strains resistant to chloroquine
47
What are the quinine drug interactions?
Potentiates neuromuscular blocking agents
Increases digoxin level
Decreased absorption with Al antacids
48
What is the definition of severe malaria?
```
Impaired consciousness/coma/convulsions
Severe normocytic anemia
Renal failure
Pulmonary edema
ARDS
Circulatory shock
Spontaneous bleeding
Jaundice
High parasitemia (>5%)
```
49
What organism typically causes severe malaria?
P. falciparum
50
What is the tx for severe malaria?
Quinidine gluconate 600mg IV q12H
PLUS
Doxycycline 100mg IV q12H x 3-7 days
51
What is the resolution time for severe tx?
Fever should break within the first 48 hours and blood should clear of parasites within 5 days
52
Does malarial infection produce immunity?
NO
53
What is artemisinin?
A blood schizonticide used to tx severe multidrug resistant P. falciparum
54
What is the MOA of artemisinin?
free radical production within food vacuole following cleavage of drug’s endoperoxide bridge by heme iron in RBC
Covalently binds and damages malarial proteins
55
How is artemisinin distributed?
PO,IV, rectal
56
What are the ADRs of artemisinin?
Overall safe, N/V/D
| High doses neurotoxic and QT prolongation
57
What is pyrimethamine?
Antifolate agent for blood schizonticide and sporontocide
58
What is pyrimethamine effective against?
P. faciparum
59
What are the ADRs of pyrimethamine?
Megaloblastic anemia
- --Folic acid replacement
- --Reverse with leucovorin
60
What is the first line tx for Giardia in people >/= 8 years old?
metronidazole (Flagyl) 250mg po TID x 7 days
61
What are the ADRs of metro?
abdominal discomfort, N/V, metallic taste, disulfiram rxn with ETOH
62
What is an alternative therapy for giardia?
Nitazoxanide 500mg po BID x 3 days
63
What are the ADRs of Nitazoxanide?
abdominal pain, N/V/D, HA
64
What does the drug tx for amebiasis depend on?
Clinical presentation! This depends mainly on location
Intestinal= asymptomatic, dysentery, or colitis
Extraintestinal= primaryily liver abscess
65
How are asymptomatic patients tx for amebiasis?
Tx with luminal agents only- non absorbable agents
66
How are all symptomatic patients tx?
With a luminal agent plus a tissue amebicide
67
What are the drug choices for asymptomatic or luminal amebiasis?
Paromomycin 500mg TID x 7 days- use if preggo
| Diloxamide 500mg TID x 10 days
68
What is the tx for severe intestinal dz or liver abscess?
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
When are luminal agents effective?
To tx the asymptomatic colonization state or following tx of invasive dz
70
What are the luminal amebicides?
Iodoquinol, Diloxanide, Paromomycin
71
What is iodoquinol effective against?
E. histolytica luminal trophozoites and cyst forms only
72
What are the ADRs of iodoquinol?
GI most common (diarrhea)
| Optic neuritis, optic nerve atrophy (rare)
73
How long does a pt need to be tx with iodoquinol?
650mg po TID x 20 days
74
Pts intoletant to what should not receive iodoquinol. Why?
IODINE- drug molecule contains iodine, nIncreases body iodine content which may persist for months => mild thyroid enlargement
75
What are signs of iodine toxicity to look for in pts taking iodoquinol?
Itching, rash, and fever
76
What is diloxanide used to tx?
asymptomatic shedders of cysts; not available in US or Canada
77
What are the ADRs of diloxanide?
Flatulence, dry mouth, pruritis, urticaria
78
When is diolxanide CI?
Preggo and
79
What is paromomycin?
Aminoglycoside antibiotic
80
How does paromomycin work?
cell membrane leakage
| decreases normal flora which is source of food for amebas
81
What are the ADRs of paromoycin?
GI distress and diarrhea
82
What is the mixed Amebicide?
metronidazole
83
When is metro the DOC?
For extraluminal amebiasis- kills tophozoites but not cysts
84
What is the MOA of metro?
nitro group of metronidazole serves as electron acceptor, forming reduced cytotoxic cmpd that bind proteins and DNAdeath
85
When should metro be adjusted?
In severe liver dz
86
What is the regimen for mild- mod dysentery?
flagyl + paromomycin or iodoquinol to clear cysts
87
What is the regimine for severe or extraintestinal infection?
flagyl + paromomycin
88
What are the ADRs of metro…againt?
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
What are the systemic/tissue amebicides?
Chloroquine, emetine, and dehydroemetine
90
When is chloroquine used in amebiasis?
in combo with metronidazole and diloxanide furoate to tx and prevent amebic liver abscesses
91
When are emetine and dehydroemetine used?
to treat liver abscesses unresponsive to flagyl
92
How long is the duration of tx for emetine?
Limited to 10 days d/t toxicity- dehydroeme is less toxic
93
How long is the half life of emetine?
5 day, 1 IM injection lasts one month
94
What are the ADRS of emetine?
Injection site pain, transient nausea, neuromuscular weakness, dizziness, rash, cardiotoxicity- arrhythmias, CHF
95
What worms are parasites?
Necatoriasis (hookworm)
Enterobiasis (pinworm)
Ascariasis (roundworm)
Neurocysticercosis (tapeworm)
96
What do anthelmintic drugs need to do in order to be effective?
Penetrate the cuticle of the worm
| Or gain access to its alimentary tract
97
How do anthelmintic drugs work?
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
What are the anthelmintic drugs?
Mebendazole
| Albendazole
99
What is the tx for Enterobiasis (pinworm)?
Mebendazole 100mg x 1, may repeat in 14 days
| For all persons > 2 years
100
What is the alternative tx for pinworm?
Albendazole 400mg x 1, repeat in 14 days
| For all persons > 2 years
101
What re the ADRs for Albendazole?
abdominal pain, N/V, Stevens-Johnson syndrome, hematologic effects (pancytopenia, thrombocytopenia, leukopenia, aplastic anemia), hepatotoxicity
102
How is necatoriasis (hookworm) tx?
Mebendazole 100mg po BID x 3 days
OR
Albendazole 400mg po x 1
(For all persons > 2 years)
103
How is ascariasis (roundworm) tx?
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
Why is it important to have caution when tx neurocysticercosis ( tapeworm)?
Sudden destruction of parasites may trigger inflammatory response and seizures
105
Does elimination of the parasite in tapeworm mean there will be neuro improvement?
NO
106
What are the options for tx tapeworm?
Surgery
Anticonvulsants
Albendazole 400mg BID +/- dexamethasone 6mg daily for 8-30 days
107
What is mebendazole?
Broad spectrum antihelminthic
108
How is mebendazole prescribed?
100mg x1 and repeat in 2 weeks
109
How does menendazole work?
Irreversibly inhibits glucose uptake in susceptible nematodes; also interferes with assembly of microtubules
110
What is mebendazole used to tx?
Whipworm, roundworm, hookworms, pinworms
111
How is the efficacy of mebendazole increased?
By chewing tablets- poorly absorbed
112
What are the most common ADRs of mebendazole?
Abdominal discomfort and diarrhea
113
When is mebendazole CI?
pregnant patients in first trimester, in children
114
What is albendazole?
Broad spec antihelminthic that enters the CNS and cysts and is larvicidal
115
How is albendazole administered?
On an empty stomach for luminal parasites and with a fatty meal for extraluminal dz
116
Short term albendazole has few ADRS( hA/N). what is the risk with high doses or long term therapy?
Hepatotoxicity, pancytopenia, inflammation in CNS HA, voniting, hyperthermia, mental changes, convulsion
117
What should you do if giving high or long doses of albendazole to your pt?
baseline LFT’s and a CBC every 2 weeks
118
When is albendazole CI?
pregnant patients in first trimester, in children
119
What is the MOA of niclosamide?
Inhibition of mitochondrial anaerobic phosphorylation of ADP no energy
120
What is the ROA of niclosamide?
PO- little is absorbed from the GI
121
When is niclosamide indicated?
Tapeworm infestation- Cestodes
122
What are the ADRs of niclosamine?
Very little since not absorbed from GI
| Some mild GI disturbance
123
What do you need to give your pt prior to niclosamide?
Laxatives to purge the OVA
124
What is pyrantel pamoate used for?
Roundworms, pinworms, hookworms
| Poorly absorbed and used only for intestinal parasites
125
How does pyrantel pamoate work?
Acts as a depolarizing neuromuscular blocker inducing worm paralysis
126
What are the ADRs of pyrantel pamoate?
mild, infrequent and transient = most common = GI (N/V/D)
127
Is pyrantel pamoate available OTC?
Yes as Pin-Rid or Pin-X
128
What is pyrantel pamoate not active against?
Migratory stage and ova
129
What are the CI to pyrantel pamoate?
pregnant patients in first trimester, in children
130
What is the MOA of praziquantel?
Increases cell membrane permeability to calcium causing paralysis, dislodgement and death
131
When is praziquantel effective?
wide variety of nematode, trematode and cestode infections
132
How is praziquantel absorbed and excreted?
PO and urine/bile
133
What should you admin to a pt with tapeworms following praziquantel?
of a purgative- dead worms may release embryos that may mature and become infectious
134
How long should praziquantel therapy be prescribed for?
ONE DAY
135
What should your pts be educated about when taking praziquantel?
Should be taken after meals with full glass of water and never chewed
136
What are the most frequent ADRs of praxiquantel?
drowsiness, dizziness, HA, GI upset – appear within 24 hours and go away in the next 24-48
137
Which drugs may interact with praziquantel and cause tx failure?
anticonvulsants
138
Should praziquantel be taken when preggo?
Nope
139
What is the MOA of thiabendazole?
affects microtubular aggregation
140
What is thiabendazole active against?
threadworms, cutaneous larva migrans and early stages of trichinosis (nematodes)
141
What are the ADRs of thiabendazole?
N/V, anorexia, dizziness
| Erythema multiforme, SJSfatalities
142
When is thiabendazole CI?
Preggos
143
What is diethylcarbamazine used to tx?
filariasis (elephantiasis) by immobilizing microfilariae thus susceptible to host defenses
Combine with abendazole
144
What are the ADRs of diethylcarbamazine caused by?
host rxn to killed organisms
Severity related to parasite load…fever, malaise, rash, myalgias, arthralgias, HA, leukocytosis tx with steroids, antihistamines
145
What is the causative organism in onchocerciasis? What carries it?
Onchocerca volvulus
Black fly
Microfiliaria(offspring) cause the actual dz
146
What are the symptoms of onchocerciasis ( river blindness)?
Severe itching, subcutaneous nodules, ocular lesions often resulting in blindness (blindness due to years of assault)
147
What is the tx for river blindness?
Ivermectin- can also use against scabies and threadworm
148
How often should ivermectin be used?
Tx once yearly until the adult worms are dead
149
What is the ADR of ivermectin?
Allergic/inflammatory response: Mazotti-like reaction (fever, HA, dizziness, somnolence, hypotension, arthralgia, edema, lymphadenopathy, ocular damage, rash, pruritis, synovitis)
150
When is ivermectin CI?
Preggo
