reducethe duration of disease. However response to
therapy varied. Clinical improvement was
experienced in one of three patients.
4
The
administration of oral vitamin A was initially based
on the hypothesis that PRP occurred as a result of
vitamin A deficiency. However, it was revealed later
that patients oftenhad normal level of vitamin A.
Other investigator proposed another hypothesis that
the lack of clinical response to vitamin A was resulted
from lack of retinol-binding protein, a specific
transport protein of vitamin A. In spite of the unclear
linkage between PRP and vitamin A metabolism, it is
well-noted that vitamin A plays a significant role in
the treatment of PRP. Clinical response to vitamin
Aseemed to be related to the pharmacological
action.(Cohen et al., 1989)
.
The first line treatment of
PRP is the oral retinoids.(Klein A et al., 2010)
Isotretinoin was reported effective both in adult and
juvenile type PRP.The clinical improvement was
experienced by 60% to 95% after 16 to 24 weeks of
isotretinoin therapy. The daily dosage varied, ranging
from 0.5 to 3.19 mg/kg. Another study reported the
lower daily dosage of 1 to 1.5 mg/kg was
adequate.Etretinate, an aromatic retinoid, was
reported helpful at a daily dosage of 1 mg/kg. Clinical
improvement was seen after 20 weeks of etretinate
therapy. Compared to isotretinoin, etretinate has
longer half-life.(Dicken CH et al., 1987)
Alitretinoin at a dosage of 30 mg per day was
reported helpful as an alternative treatment. The
therapeutic effect of alitretinoin was considered
through itsanti-inflammatory mechanism. In vitro,
alitretinoin inhibited of proinflammatory cytokines
such as TNF and IL-12/IL-23.(Amann PM et al.,
2015)
.
Vitamin A and retinoids has the same potential
adverse effectsof hypervitaminosis A such as
teratogenicity, abdominal pain, visual disturbances,
dryness, dizziness, and hypertriglyceridimia.
8
Routine laboratory tests should be performed to
monitor any adverse effects.Hypervitaminosis
vitamin A was reported in patients obtaining systemic
vitamin A more than 50,000 IU daily. However,
retinoids do not seem to disturb liver function as it is
not stored in the liver like vitamin A.
5
Administration
of oral vitamin A for treatment of PRP has been
described in previous literature and textbooks, but the
effective amount and period of vitamin A has not
been specifically described. The administration of
vitamin A is suggested only for adults. Children are
considered to be more susceptible to its toxicity.
Pregnant and childbearing-age women are also
restricted due to its teratogenic effect.(Randle HW et
al., 1980).
Antimetabolites like methotrexate is often used in
patients of PRP. Clinical improvement usually
appears after 6 weeks therapy, and complete response
is often achieved by week 12 to 16. However, patients
refractory to convential therapy often require
combination therapy with retinoids and methotrexate.
In a study, 22 patients were treated with etretinate 25-
75 mg/day or isotretinoin 40 mg twice daily. Half of
the patients also received methotrexate at a weekly
dosage of 5-30 mg. After 16 weeks, 8 of 11 patients
in combination therapy showed clinical improvement
of 50-95%.
4
However, due to teratogenicity, oral
retinoids including isotretinoin, etretinate and
alitretinoin are not available in Indonesia.
In our patient, clinical improvement did not occur
after 20 weeks of methotrexate administration as
monotherapy, yet marked improvement did appear
after 16 weeks of oral vitamin A administration in
concurrent with methotrexate at a weekly dosage of
10 mg. Liver function tests were routinely performed
as the concurrent use of methotrexate and vitamin A
increased the risk of hepatotoxicity.In this patient, we
routinely monitored the potential side effects by
clinical symptoms and laboratory markers. There was
no elevation of liver enzymes. However, there are few
similar case reports to date. Hereafter, as more cases
become accumulated, we would expect to clarify the
effective minimum dosage and optimal dosing period
of vitamin A therapy for PRP patients.
4 CONCLUSION
PRP is a rare and chronic skin disorder that often
progresses to erythroderma and causes a disabling
skin disorder. Finding a suitable management has
always been difficult. Although the linkage between
PRP and vitamin A metabolism remains intriguing
and individual clinical response to therapy exists, it is
worth to offer vitamin A therapy for patients with
refractory PRP as a favorable alternative. Careful
monitoring should be routinely performed to avoid its
potential adverse effects. Due to restricted
prescription of retinoids in some countries, oral
vitamin A is a favorable alternative for patients
without any contradictions.
REFERENCES
Amann PM, Susic M, Gluder F, Berger H, Krapf W and
Loffler H.2015.Alitretinoin (9-cis retinoic acid) is
effective against pityriasisrubrapilaris: a retrospective
clinical study. ActaDermVenereol; 95: 329-31.