Why is it difficult to treat viral nfxn
- Viruses use host cell enzymes and substrates to reproduce
- Drugs that affect these viruses will also affect the host
- Successful drugs affect the biochemical processes unique to viral replication.
Herpes Simplex Viruses (Type 1)
- Type 1 (HSV 1)
- Cause classic cold sore
- Severity increases with age and immunosupression
Herpes Simplex Commonalities
- There is not really a clear divide between the two types, however. HSV1 can also cause genetal sores, and vise versa.
- Both viruses lay dormant within a nerve route until outbreak.
- Most infective at time period immediately before outbreak (lesion).
- After primary infection the virus remains in the body in a dormant state in the nerve ganglia
- patient is asymptomatic
- Reactivation of infection triggers the virus to travel the pathway of the nerve to the skin surface
- Triggers may be:
- Physical or psychological stress
- How spread
- Direct contact
- Autoinnoculation (Spread of either type from one body part to another)
- Last 3-10 days
- Active shedding
- First 3-5 days
- Spread by:
- Respiratory droplets
- Direct contact with active lesion
- Virus containing fluid
- 1 in 4 women will acquire HSV
- Current testing decreased risk of acquiring by 75%
- Did not effect HSV1 if already infected
- Not effective for men
- Did not ultimately come to market.
- AKA Shingles
- Caused by reactivation of latent Varicella-zoster virus
- Those previously exposed to chicken pox
- Contagious to those never exposed to chickenpox
- Dormant virus resides in the dorsal root ganglia of the sensory cranial and spinal nerves
- Multiple lesions occur on the skin innervated by the infected nerve
- Disease of immunosuppression
- Vaccine for chicken pox/shingles
- For those over 60
- Prevents shingles in over half of those over 60---reduces pain in others.
- Allergic reactions to gelatin
- Allergic reactions to neomycin (aminoglycocides)
- Weakened immune system
- Cancer treatment
- Hx of leukemia, lymphoma
- Temp over 101
Purine Nucleoside Analogs
- DNA polymerase inhibitors
- Suppresses synthesis of viral DNA
- First choice for infections caused by herpes simplex and varicella-zoster virus
- Administered topically, orally and IV
Acyclovir (Zovirax) Adverse Effects
- Intravenous therapy
- Oral therapy
- Stinging sensations
Acyclovir (Zovirax) Pt education
- Acyclovir IS NOT A CURE
- It will not prevent spread to others
- Use of condoms (Genital Herpes)
- No sexual contact when active lesions are present
- Use of OTC lotions, creams may delay healing and cause spread of lesions, may lead to selfinnoculation!
- CMV is related to the herpes virus and is present in almost everyone.
- Especially seen in those who are immunosuppressed
- AIDS (brought CMV to the forefront), Chemo, Transplants
- Infections of the eye are very common.
- Spots, bugs and spider-webs
- Light Flashes
- Blind Spots
- Blurred Vision
- Obstructed areas of vision
- Sudden decrease in vision
Basically destroys vision
- Prodrug version of ganciclovir (acyclover). Becomes identical to acyclover after metabolism.
- Can be given orally
- Adverse effects: Blood dyscrasias (decreases of WBCs, RBCs, and platelets)
- Should be taken with food
- Has potential for mutagenesis and carcinogenesis….handle carefully
- Take intact…no crushing or chewing, increases mutagenic and carcinogenec properties. Prep should be done under a hood, with gloves, wash hands.
- If pregnant, DO NOT HANDLE GANCYCLOVIR
- HCW use cytotoxic chemo precautions
- 6 types of Viral Hepatitis: A; B; C; D; E; G
- Vary by:
- Mode of transmission
- Manner of onset
- Incubation periods
- Enteral Forms: A and E (Vaccine for A)
- Parenteral (needle sticks) Forms: B,C E G (Vaccine for B)
- E occurs in both, so its more virulent.
- C is more contagious than HIV, so use precautions when treating pt with HepC.
Accute vs. Chronic Hepatitis
- Lasts ~ 6 months
- Liver inflammation, jaundice, Elevation of Liver enzymes
- Usually resolves spontaneously.
- All forms can be accute.
- Only B, C ,D and G can cause chronic hepatitis (not A and E).
- 90% caused by B and C
- 1.5% of Americans have chronic infection with HBV or HCV
- 5 times more than the number infected with HIV
- Interferon Family (used to treat) can be Alpha, Beta, Gamma
- Parenterally, IM or SQ
- Therapeutic effects
- Improved liver histology in 40%
- After 12 months-40-50% have normalized liver function
- Adverse effects
- Flu-like syndrome
- Available in 2 formulations
- Inhaled (For Respiratory Syncytal Virus –RSV )
- Oral ( For Chronic Hepatitis )
Action is really unknown although several actions are thought to be actively anti-viral
Contraindicated for use in pregnancy nor should pregnant nurses administer the drug (Aerosol)
DO NOT CRUSH!
REBETRON: RIBAVIRIN PLUS INTERFERON ALFA-2B
Current treatment for chronic hepatitis C
- Ribavirin-nucleoside analog; Mechanism unknown
Kit—contains two drugs, Ribavirin - PO, Interferon Alfa - SQ
- Flu-like symptoms
- Hemolytic anemia
- Birth defects
- Treatment of HCV
- Approved for stand-alone therapy… initial research seems to identify improved effectiveness with ribavirin
- Long-acting form of interferon alpha 2b
- Half life of 40 hours vs 2-3 hrs
- Can be given 1x week vs 3 times a week
- Identical side and toxic effects
Drugs for Flu
- Influenza Vaccine
- Annual. Changes every year in accordance with what is predicted to come to the US from Asia the year before. Not always accurate.
- Inactivated virus. Cannot get flu from vaccine, but may have rxn due to egg content in vaccine serum.
- 70-90% effective
- Protection lasts 6 months
- Elderly population works only 30-40%, and will last only ~ 4 months
- Given IM
- Always ask "Are you allergic to eggs? Have you ever had a rxn to flu vaccine?"
- Use to give a live virus called Guillin Berette. Could cause paralysis. Will have some pts who will not take flu vaccine now because they're still afraid of it.
- Live, attenuated (virulent components removed) Influenza Vaccine (LAIV)
- Temperature sensitive (Cold Adapted). Must be kept cold, almost frozen.
- Trivalent; composed of and specific to three viruses.
- Intranasal, rub nares together, do not blow nose afterwards.
- Approved last year
- Not for everyone
You should NOT use Flu Mist if you:
- are under 5 years of age
- are aged 50 years or over
- have asthma or other reactive airway diseases
- have chronic underlying medical conditions that may predispose you to severe flu infections
- have problems with immune suppression, including those with immune deficiency diseases, such as AIDS or cancer, and people who are being treated with drugs that cause immunosuppression
- are allergic to eggs or to a previous dose of the vaccine
- children or adolescent receiving aspirin or other salicylates ----->(Reyes Syndrome).
- History of Guillain-Barre’ syndrome
- Pregnant woman
Flu Mist Special Considerations
- Children age 5-8 who have not received injection need 2 doses at least 6 wks apart
- Must be stored at 15 degrees C
- Thaw in hand and administer immediately OR
- Thaw in refrigorator
- Should only be thawed for 24 hours
- Administer 1/2 of single use sprayer in one nostril and remainder in other
- In upright position
- Don’t repeat if sneezes
- Mild illness is OK, if fever >101 degrees, do not give.
- Cost ~$46 per dose
- Other immunizations??
- Inactivated viruses OK
- Live viruses 4 weeks apart from flu inhaler.
Amantadine and Ramantadine (1st gen flu meds)
- First Generation Drugs
- Used for prophylaxis and treatment of Influenza A
- Should not take the place of vaccination
- Adverse effects:
- difficulty in concentration
- Sleep disturbances
- DO NOT use in pregnant and lactating women
Oseltamivir and Zanamivir (2nd gen flu meds)
- 2nd Generation
- Neuraminidase Inhibitors
- Suppress both Influenza A and B
- Not approved for prophylaxis ~ seems to have some efficacy
- Only for use in those >18
- Symptoms for no more than 2 days
- Oseltamivir ~ oral
- Zanamivir ~ Inhaled powder
Human Papaloma Virus (HPV) Vaccine
- Gardasil Vaccine:Targets 4 viruses that cause up to 70% of all cervical cancers and 90% of genital warts
- Cervarix: Targets 2 viruses known to cause cervical cancer.
- CDC recommends vaccination for all girls 11 -12 years, and all boys age 9-26 (gardacil)
- 13-26 years of age if not already vaccinated (only ages tested)
- Series of 3 injections over 6 months
- No serious side effects (yeah right) but will see fainting, seizures
SARS: Severe Acute Respiratory Syndrome
- Coronvirus ~SARS-CoV
- Closely related to common cold
- Results in atypical pneumonia
- Time from exposure to onset of symptoms, 2 - 11 days
- Fever ~ 100.4 or higher
- Dry, nonproductive cough
- Difficulty breathing
West Nile Virus
- Detection of IgM antibody to WNV in serum or CSF
- Collected within 8 days of disease onset
- Recent vaccination or infection with other associated viruses may cause a false positive
- Plague Reduction Neutralization Test (PRNT)
West Nile Virus (WNV)
- First documented in 1937
- Similar to yellow fever, dengue and St. Louis encephalitis
- Risk factors:
- Advanced age
- Mild infection
- Sudden fever with
- Symptoms last 3-6 days
- Severe infection
- 1 in 150 Cases
- aseptic meningitis