Download Guidelines for Use of Antivirals for Herpes Zoster

National Skin Centre, Singapore
Guidelines for Use of Antivirals for Herpes Zoster
Diagnosis of herpes zoster
1). Herpes zoster is diagnosed clinically with the presence of painful grouped
vesicles in a dermatomal distribution. Prior to the onset of rash, patients may
experience prodromal symptoms of pain, itch or paraesthesia over the involved
dermatome.
2). In the history taking, patient should be asked about possibility of underlying
immunocompromised states, eg: history of renal transplant on
immunosuppressive, chronic dermatosis on long term systemic corticosteroid,
recent history of weight loss.
3). During physical examination, besides examining the skin lesions, patient
should be examined carefully for the possibility of underlying medical conditions,
eg: hepatosplenomegaly, lymphadenopathy.
4). Basic investigations should include full blood count with peripheral blood film
examination, urine FEME. Other investigations should be performed if indicated
(eg: chest X-ray, malignancy screening).
Antiviral medications
Antiviral
Total cost
(approximate)
S$ 14.70
Cost per day
(approximate)
S$ 2.10
S$ 207.93
S$ 29.70
* Valtrex
(valaciclovir)
Recommended
treatment
800 mg, 5 times per
day for 7 days
* For children,
20mg/kg (not to
exceed 800mg),
QDS
800 mg, 5 times per
day for 7 days
1 gm, 3 times per
day for 7 days
S$ 193.8
S$ 27
# Famvir
(famciclovir)
250 mg, 3 times per
day for 7 days
S$ 387.60
S$ 55.40
* Generic acycovlir
# Zovirax
Note:
*
Available in NSC
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#
Retail price from private pharmacies.
Use of antivirals
1)
Aims of treatment:
a)
b)
c)
2)
Shorten duration of acute illness.
Reduce the severity of acute illness.
Reduce the risk of herpes associated pain, especially chronic pain.
Available data on clinical outcomes of herpes zoster for patients treated
with antivirals:
Patients treated with valaciclovir heals significantly faster than patients
treated with acyclovir and patients not treated with antiviral. Patients
treated with acyclovir may form scab faster than untreated patients, but
the duration taken for complete healing was not significantly different.
The incidence of zoster associated pain decreases with time in all
patients. However, older patients have higher incidence of zoster
associated pain at all time intervals from onset of rash compared to the
younger patients. The incidence of zoster associated pain at 1 month for
patients older than 50 years-old was 62%, compared to 29% for those
younger than 30, while the corresponding incidence by 6 months was 20%
and 7% respectively.
Significantly fewer patients treated with valaciclovir have zoster associated
pain at various time intervals from onset of zoster compared to patients
treated with acyclovir and untreated patients. The corresponding
incidences of zoster associated pain at 1, 3, 6 months after onset of rash
for patients treated with valaciclovir (23.5%, 5.9%, 0%) were significantly
lower than those treated with acyclovir (48.3%, 24.1%, 17.2%) and
untreated patients (49.4%, 27.4%, 17.7%). The difference between
patients treated with acyclovir and untreated patients was not significant.
3)
Indications for use of antivirals:
a)
Patients at high risk of disseminated herpes, eg:
immunocompromised patients ( patients on chemotherapy, patients
on long term corticosteroids, transplant patients on
immunosuppressive )
b)
Patients at high risk of prolonged zoster associated pain, eg:
patients older than 50-year-old.
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4)
Timing of antivirals:
Antivirals should be used as early in the course of disease as possible.
The recommended cut-off time of 72 hours may not be applicable to all
patients, especially immunocompromised patients. These patients should
be given antivirals as long as the disease is still active.
5)
Choice of antivirals:
a)
Acyclovir should be the antiviral of choice unless the use of antiviral is
specifically aim to reduce the incidence of zoster associated pain.
b)
Valtrex (valaciclovir) is thus indicated for:
(i)
6)
Patients older than 50.
Adjunctive treatments:
(i)
Pain killers. Patients should be prescribed pain killer as pain is
present in more than 90% of the patients during the acute illness
and it is also often regarded as having the greatest impact on
patients’ life, eg: Naproxen sodium 275mg bd.
(ii)
Sleeping pills. Many patients have insomnia during the illness and
will benefit from short term use of sleeping pills, eg: Dormicum 7.5
mg ON, Valium 5mg ON.
(iii).
Skin care. During the acute blistering phase of the disease, patients
treated with saline compress, the blisters may be pricked and
covered with tetracyclince ointment and melolin dressing.
Emollients, eg: aqueous cream, should be applied once crusting
takes place.
(iv). Ophthalmic involvement. In herpes zoster ophthalmicus, the
ophthalmic division of the fifth cranial nerve is involved. If the external
division of the nasociliary branch is affected, with vesicles on the side and
tip of the nose (Hutchinson’s sign), the eyeball is involved in 76% of the
time, as compared with 34% when it si not involved. Vesicles on the lid
margin are virtually always associated with ocular involvement. Patients
with ophthalmic zoster should be seen by an ophthalmologist.
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(V). Management of postherpetic neuralgia (Zoster-associated pain)
a). Topical treatment
(i). First line
Capsaicin cream 0.025%, applied every few hours. Capsaicin itself
may
cause burning sensation.
(ii). Second line
Local anesthetis (eg: 10% lidocaine gel, 5% lidocaine-prilocaine,
lidocaine patches ) may acutely reduce pain.
Topical aspirin in ether or chloroform (eg: 750 mg of acetylsalicylic
in 20 to30 ml of liquid).
b). Systemic treatment
(i). First line
Simple analgesics (eg: paracetamol, NSAIDS)
Tricyclic antidepressants (eg: amitriptyline and desipramine, at 25 to
75 mg in a single nightly dose).
(ii). Second and third line
Anticonvulsants, such as carbamazepine, valproate.
Neuroleptics, such as chlorprothixene, phenothiazines.
H2 blockers, such as cimetidine.
Gabapentin, may be added in escalating doses up to 3200 mg/ day.
Opiate analgesics.
Patients with difficult to manage herpes associated pain should be
referred to the “Pain Clinic” for expert management.
Annex 1
Clinical data on antiviral usage for herpes zoster
a)
Duration taken for healing of rash:
Duration for scabbing to
occur (days)
Duration for complete
healing of rash (days)
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No
treatment
11.1
Acyclovir
8.2*
Valaciclo
vir
6.8*
20.8
16.4#
13.4*
# = statistically not significant
* = statistically significant
b)
Herpes associated pain at 1, 3, 6 and after six months for different
age groups if without treatment:
At 1 month *
At 3 months *
At 6 months
More than 6 months
<30 years
29%
11%
7%
7%
30 - 50 years
46%
24%
18%
16%
> 50 years
62%
39%
23%
20%
* = statistically significant among different age groups
c)
Herpes associated pain at 1, 3, 6 and after 6 months for different
treatment groups:
At 1 month
At 3 months
At 6 months
More than 6 months
No
treatment
49.4%
27.4%
17.7%
15.9%
Acyclovir
Valaciclovir
48.3%
24.1%
17.2%
13.8%
23.5%*
5.9%*
0%*
5.9%
* = statistically significant compared to no treatment group
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Herpes Zoster
Immunocompetent
Paediatric
( < 12 )
Adults
( < 50 )
( 13 - 50 )
> 72 hrs
Immuno-compromised
Generic acyclovir
until lesions healed
( > 50 )
< 72 hrs
> 72 hrs
< 72 hrs
> 72 hrs
- No antiviral
- skin care, etc
- No anti-viral
-skin care
-analgesic
- antibiotic
- sedation
Generic
acyclovir
- No anti-viral
-skin care
-analgesic
- antibiotic
- sedation
Generic acyclovir
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< 72 hrs
Valtrex