DISCUSSION
Osteoporosis is considered to be the one of the leading health care
problem and hence with our ageing population the prevalence and cost of
osteoporosis is increasing [43]. Osteoporosis is a
common skeletal disease characterized by bone mass reduction and bone
micro architecture deterioration including bone fragility and high risk
of fractures. Osteoporosis is diagnosed using several tests such as
calcium test, vitamin D test and DEXA scan. Among these tests calcium
and vitamin D tests are easily affordable however Dual Energy X-rays
Absorptiometry (DEXA) scan is not affordable for majority of patients
particularly in Pakistan. Furthermore DEXA scan and vitamin D tests are
performed following the treatment duration of three months to check
whether the treatment strategy is efficacious or not. Among the
treatment strategies non-pharmacological treatment as well as
pharmacological treatment is available for osteoporosis.
Non-pharmacological treatment includes the life style modifications,
tobacco use and excessive use of alcohol and caffeine should be
discouraged, promotes intake of balance diet with calcium and vitamin D,
regular physical exercise and preventing minor accidents like fall, etc.
Pharmacological treatment of osteoporosis include anti-resorptive agents
such as bisphosphonates (Alendronate, Alendronate plus D, Risedronate
and Zoledronic acid ), estrogen, calcium and vitamin D supplements,
calcitonin and selective estrogen receptor modulators (Raloxifene) and
bone anabolic agents including recombinant human Para-thyroid Hormone
(rhPTH).
In current study among 120 patients 69% patients were treated with
bisphosphonates and 31% were treated with rhPTH. However more
significant increase in Bone Mineral Density was observed in patients
using Para-thyroid hormone. Lumber spine BMD was greatly increased in
patients using Para-thyroid hormone as compared with the patients using
bisphosphonate. In the first year of treatment rhPTH increase BMD by
8-9%, while bisphosphonates and estrogen therapy increase BMD 3-5%
during the same time period. The results are comparable with the study
conducted by Shen.L (2011) who reported that Parathyroid hormone therapy
show areal BMD than therapy with bisphosphonnates. His result showed
that as compared to treatment with bisphosphonates lumbar spine BMD
increase significantly by use of PTH. Duration and dose dependent
increase in hip BMD as compared to bisphosphonates treatment is induced
by PTH. Distal radius BMD was significantly lower by treatment with PTH
as compared to alendronate.
Bisphosphonates (the anti-resoptive agents) include the drugs
etidronate, tiludronate, alendronate, and risedronate, etc. Among them
the first generation bisphosphonate i.e.; etidronate (20mg/kg daily for
2 weeks followed by 10mg/kg for 10 weeks, a total of 12 weeks followed
by 11 to 13 weeks of calcium supplementation) somehow decrease the rate
of vertebral fractures but its long term use lead to prolong
bisphosphonates retention and impaired mineralization thus causing
adverse effects. Tiludronate (400mg daily oral dose for 3 months),
alendronate (10mg once daily or 70mg once weekly and could be used upto
10 years however can be withdrawn after 5 years in some women), and
risedronate (5mg once daily taken orally for up to7 years), Ibendronate
(100-150mg every 3 months) that are the second and third generation
bisphosphonates are much more potent and have greater therapeutic window
then etidronate. Etidronate (Disodium); 400mg in a packing of 10s costs
for about 290 Rs, Alendronadte(Na); 70mg with a packing of 10s is
available in the cost for about 1500 Rs, Risedronate(Na); 35mg in
packing of 4s price ranges from 400-700 Rs. Ibendronate; 150mg comes in
price of about 400 Rs (Table.3).
Recombinant human Para-thyroid Hormone (the anabolic agent) include
teriparatide with the brand name; Forteo is given as a subcutaneous
injection in thigh or abdominal wall, in a dose of 20-mcg daily in a
2.4-ml prefilled delivery device and should not be used for more than 2
years. Price of one Forteo injection 20mcg in Pakistan is about 27000
Rs, which makes it unaffordable for majority of the osteoporotic
patients.
In the current studies it has been observed that risks of vertebral
fractures are reduced by long term use of bisphosphonates as compared to
those patients who withdrew bisphosphonate therapy earlier. In a
previous study conducted by Robert A. Adler (2016) showed that
post-menopausal women receiving alendronate for 10 years had fewer
clinical vertebral fractures than those who after 5 years were switched
to placebo. Whereas few morphometric vertebral fractures were found in
women who received zoledronic acid’s 6 annual infusions as compared to
those who after 3 years were shifted to placebo.
In our study we found rhPTH to be more effective in improving bone
architecture and reducing the risk of osteoporosis associated fractures
when analyzed in comparison to bisphosphonates. Whereas in a previous
study conducted by Hodsman.A (2005) reported fracture risks are
significantly reduced by bone mineral architecture improvement as well
as overall bone mass enhancement by use of teriperatide. In patients
with severe osteoporosis for prevention of fractures PTH should be
considered as an alternative therapy to existing anti-resorptive agents.
In improving BMD of lumbar spine teriperatide is superior to
anti-resorptive therapy (alendronate).
As we have compared bisphosphonates and rhPTH in curing osteoporosis or
osteoporotic fractures we find rhPTH to be more efficacious then
bisphosphonates but unfortunately due to high cost of rhPTH therapy in
Pakistan patients does not afford rhPTH therapy and physician prefer
prescribing bisphosphonates keeping in view patient’s affordability, as
a result of which bisphosphonates are more recommended and prescribed in
Pakistan.