Antihistamines, Antifungals, Antivirals

Question 1

Sources of Histamine:

Answer 1

1. Mast Cells (intestinal mucosa, skin and lungs)
2. Basophils (in blood bound to heparin)
3. CNS in neurons (in synaptic vesicles)

Question 2

Mechanism of H1 antihistamines:

Answer 2

Competitive blockade of H1 receptors (H1 receptor blockers)

Question 3

Pharmacologic effects of H1 antihistamines:

1. Absorption
2. Onset
3. Duration
4. Metabolism

Answer 3

1. Well absorbed orally
2. Rapid onset = 15-30 minutes
3. Duration = 3-6 hours
4. Metabolism primarily by over (some kidney)

Question 4

How do H1 antihistamines affect the CNS?

Answer 4

Produce depression (Sleepiness)
Treat motion sickness

Question 5

What is the action of H1 antihistamines on the Autonomic nervous system and Peripheral nervous system respectively?

Answer 5

ANS: Blocks constriction of respiratory smooth muscle

PNS: Blocks flare (wheals) and itch

Question 6

3 Adverse effects of H1 antihistamines:

Answer 6

1. Most cause sleepiness/drowsiness
2. Xerostomia (dry mouth)
3. Dry mucous membranes

• Older antihistamines caused ventricular arrhythmias

Question 7

2 types of Antihistamines

Answer 7

1. Ethanolamines
   - diphenhydramine (Benadryl)
2. Alkylamines
   - chlorpheniramine (Chlor-Trimeton)

Question 8

Name 3 non-sedating antihistamines

Answer 8

Ioratadine (Claritin) - OTC
fexofenadine (Allegra) - OTC
desloratadine (Clarinex)

Question 9

Mechanism of action for H2 antihistamines:

Answer 9

1. Competitive blockage of H2 receptors (GI tract)
   - Reduces intracellular concentration of cAMP
   - Protein kinase that drives the H+/K+-ATPase pump is shut down
   * *-Inhibits basal and nocturnal gastric acid secretion (evoked by histamine)

Question 10

Pharmacologic effects of H2 Antihistamines:

1. Absorption
2. Metabolism
3. If added to H1 blockers???

Answer 10

1. Well absorbed orally
2. Very little metabolism
3. If aded to H1 blockers, blocks all cardiovascular effects of histamine

Question 11

4 clinical uses of H2 Antihistamines:

Answer 11

1. Peptic ulcer
2. Hypersecretion of gastric acid
3. GERD
4. Zollinger-Ellison syndrome (gastrin producing tumor causing hypersecretion of stomach acid)

Question 12

Name 4 H2 Antihistamines:

Answer 12

1. cimetidine (Tagamet)
2. famotidine (Pepcid)
3. nizatidine (Axid)
4. ranitidine (Zantac)

Question 13

Adverse effects of H2 Antihistamines

Answer 13

1. Minor
2. Chronic use of these drugs is associated with headache, dizziness and fatigue
3. Elderly = confusion, slurred speech, delirium and hallucinations
4. Gynecomastia in males
5. Impotence; 40% decrease in sperm count

Question 14

What is the safest and most recommended drug in H2 Antihistamine class?

Answer 14

ranitidine (Zantac)

• Fewest drug interactions

Question 15

Which drug of the H2 Antihistamine class has the most adverse reactions

Answer 15

1. cimetidine (Tagamet)
   - Inhibits cytochrome P450 to slow the clearance and increases the serum levels of many drugs
   - increases risk for overdose reactions

Question 16

What is cromolyn (Gastrocrom)?

Answer 16

A mast cell stabilizer

- Inhibits degranulation, preventing histamine release from IgE sensitized mast cells

Question 17

What is cromolyn (Gastrocrom) used for?

Answer 17

Prophylaxis of allergies, exercise-induced asthma, and asthma

Question 18

Describe when to use topical vs systemic anti fungal treatment

Answer 18

Systemic: chronic, extensive mucocutaneous candidiasis

Topical: Local candidiasis
- **May be used in conjunction with topical corticosteroids to manage inflammation

Question 19

Which of the anti fungal therapies is preferred?

Answer 19

Topical versus systemic is preferred

Question 20

How long to treat during anti fungal therapies

Answer 20

Treat for a minimum of 48 hours after symptoms subside
- usual treatment period is for 1-2 weeks

Re-evaluate at 14 days after therapy

Question 21

4 topical antifungal agents

Answer 21

1. Liquids
2. Troches
3. Pastilles
4. Powders

Question 22

nystatin (Mycostatin) mechanism of actions

Answer 22

Binds to sterols in fungal cell membrane, changing cell wall permeability allowing for leakage of cellular contents
-Topical

Question 23

nystatin comes in what forms?

Answer 23

• pastilles/troches = 4-5 troches/day for 14 days
• oral suspension = 1 tsp 4-5 times/day; rinse and hold in mouth for 2 minutes; do not eat/drink afterwards for 30 minutes; soak dentures
• ointment/cream = 4-5 times per day; may be applied to dentures prior to insertion
• powder = sprinkle over dentures prior to insertion 4-5 times per day

Question 24

When is clotrimazole (Mycelex) used?

Answer 24

when nystatin is not effective

- Not for systemic fungal infections. Topical use only

Question 25

Describe dosages of different forms of clotrimazole (Mycelex)

Answer 25

1. Troche - dissolve 1 troche 5 times/day for 14 days 2. Cream - apply twice daily 3. Solution - rinse twice daily

Question 26

What is the adverse effect of clotrimazole

Answer 26

abnormal liver function

Question 27

Name the two topical antifungals

Answer 27

1. nystatin (Mycostatin) | 2. clotrimazole (Mycelex)

Question 28

Name the systemic antifungals

Answer 28

Azole antifungals - itraconazole (Sporanox) - fluconazole (Diflucan)

Question 29

Why do you avoid systemic anti fungal drugs

Answer 29

1. Promotes resistance of fungal organisms 2. Many dangerous drug interactions 3. Hepatotoxic 4. itraconazole = severe cardiovascular side effects; neuropathy

Question 30

T or F, Reserve systemic antifungal agents for severe cases

Answer 30

True

Question 31

Name the parenteral anti fungal drug

Answer 31

amphotericin

Question 32

How is amphotericin given?

Answer 32

by IV

Question 33

amphotericin is the most effective drug for what?

Answer 33

against deep-seated mycotic infections | - used for fungal infections associated with HIV

Question 34

Treatment for viral infections includes combination therapy of?

Answer 34

Antiviral drug Topical anesthetics Fluids, vitamins/minerals, rest

Question 35

Vesicular viral lesion =

Answer 35

Contagious

Question 36

Viral vesicle breaks =

Answer 36

Open lesion with draining fluid = contagious

Question 37

How long do viral lesions last?

Answer 37

10 days

Question 38

Are antibiotics effective for viral infections? Is anything else contraindicated?

Answer 38

No, they are ineffective | - Systemic corticosteroids are contraindicated for use during viral illnesses

Question 39

Mechanism of Acyclovir (Zovirax)

Answer 39

Inhibits viral DNA polymerase preferentially, inhibiting viral replication

Question 40

How is Acyclovir administered?

Answer 40

Systemically and topically Systemic: recurrent mucosal and cutaneous herpes simplex infections Topical: herpes labialis, mucocutaneous infections

Question 41

Dosage forms of acyclovir

Answer 41

oral cream/ointment suspension injection

Question 42

2 different prescription examples for Herpes Simplex (primary infection)

Answer 42

1. Zovirax 200 mg capsules Disp: 50 capsules Sig: Take 1 capsule 5 times/day for 10 days 2. Zovirax 200 mg capsules Disp: 60 capsules Sign: Take 2 capsules 3 times/day for 10 days

Question 43

What is Xerese

Answer 43

Acyclovir 5% and hydrocoritsone 1% | External use only: lips and face

Question 44

What is Penciclovir (Denver)?

Answer 44

For Herpes labialis: apply only to lips and face | Effect not established in immunocompromised patients

Question 45

What is Famciclovir (Famvir) used for?

Answer 45

In immunocompetent patients

Question 46

Primary use for Valacyclovir (Valtrex)

Answer 46

genital herpes suppression therapy

Question 47

Side Effects of all antiviral drugs taken systemically

Answer 47

``` Bone marrow suppression Blood dispraises -Thrombocytopenia - Leukopenia - Aplastic anemia ```