Pluset
Frequently Asked Questions
(click on question to go to answer)
_____________________________________________________
• What is Pluset®?
Pluset®
is a porcine pituitary extract (PPE), which contains
both of the gonadotropins, follicle stimulating hormone (FSH) and
luteinizing hormone (LH). This product is primarily used to induce
development of ovarian follicles during the superovulatory process
in ruminant females. The objective of superovulation is to induce
multiple follicles to grow and ovulate so that their oocytes (eggs)
can become fertilised and the resulting embryos can be collected
from genetically valuable donor females and subsequently transferred
to recipient females that will gestate the embryos to term. Because
of its stimulatory activity on follicular growth, Pluset®
is also used in cases of reduced fertility (heat
stress, high milk production, ovarian inactivity, etc...) to
supplement endogenous FSH synthesis and release from the pituitary.
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• How is Pluset®
produced?
The production process comprises a number of extractions with
solvents and fractionated precipitation, in processes that take 15
days. Independent PPE fractions are produced, one for FSH and one
for LH from porcine pituitary glands from certified healthy pigs. In
addition, the extraction method is validated against any viral
contamination. To ensure the quality of the final product, the FSH
fraction and the LH fraction are each independently analysed for
both FSH & LH bioactivity. The final product is a mixture of both
fractions, in a proportion to ensure a FSH:LH ratio of 1:1 in terms
of biological activity, expressed in International Units (IU).
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• Why does Pluset®
contain LH?
LH, or luteinizing hormone, acts synergistically with FSH to
facilitate ovarian follicular growth and maturation. Characteristic
of early follicular phase growth, ovarian follicles less than 9 mm
in diameter are FSH-dependent, evidenced by the presence of FSH
receptors in the granulosa cells, but at this stage, there is a
minimal presence of LH receptors. When the growing follicles reach 9
mm in diameter, the FSH receptor disappears from the granulosa cells
while the LH receptor is more
abundant, essentially causing a switch in the follicle's dependence
from FSH to LH. Thus, the LH hormone is necessary for follicular
growth in the final stages.
Previous research has shown that gonadotropin
preparations containing FSH suppress endogenous LH release, to the
point of inhibiting final growth and maturation of the follicles and
can even prohibit ovulation. Stress during the treatment period can
also induce cortisol release, which has a direct negative impact on
LH release, thus exacerbating endogenous LH suppression. The LH
portion of Pluset®,
therefore, can supplant this hormone, when endogenous LH is
suppressed, insuring that the superstimulated follicles have the
opportunity to complete their growth and maturation.
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• Why are FSH and
LH in a 1:1 ratio?
The reason for a 1:1 ratio of biological activity in Pluset®
is because of its historical
predecessor, Pergovet®.
Pergovet®,
was human menopausal gonadotropin, or hMG, that was used because of
its excellent results and homogeneity, when compared to other, then
existent, FSH compounds. Pergovet®
was a very expensive drug to
manufacture, and thus, a decision was made to develop a PPE with the
same characteristics as hMG, namely Pluset®
with its 1:1 FSH:LH ratio in
biological activity.
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• Does a 1:1
FSH:LH ratio mean the same amount of each hormone?
No, not in terms of physical weight or amount. It simply means that
there is the same number of International Units (IU's) of
each hormone and the number of IU’s is based on biological activity.
However, since the FSH and LH hormones have a different molecular
structure, they are measured by different methods of analysis
(i.e. an IU of FSH is not the same as
an IU of LH). The quantity of
each hormone is therefore, equivalent in terms of bioactivity and
proportion of its standard. It also must be taken into account,
however, that the half-life of LH in circulation in the cow is much
shorter than FSH.
The biological activity per mg of the
LH-fraction of Pluset®
is much higher than that of FSH,
but its half-life in circulation is about 25 minutes for LH compared
to about 2.5 hours for FSH. The FSH-fraction of Pluset®
contains some 25 IU/mg, whereas
the LH fraction contains some 300 IU/mg. This means that, in each
500 IU vial, there is approximately 20 mg of FSH and 1.5 mg of LH
(i.e. mg of WEIGHT, not
mg of NIH- FSH-P1 standard). Pluset®
cannot, therefore, be compared
directly with products that use NIH mg standards because of their
different methods of analyses. Pluset®
uses a standard measuring
biological activity, whereas NIH mg standards measure by
radio-immunoassay (RIA), which is an antibody-based standard that
does not measure bioactivity.
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• Why is
Pluset®
measured in units of biological
activity?
Extractions from biological
substrates give different performances, depending on the original
raw material, which will present slight variations (depending on the
age and gender of the animal, season, etc.). Some gonadotropin
products express hormonal content in mg per unit of volume, which is
measured by radio-immunoassay (RIA), an analytical technique that
employs antibodies to FSH and LH. These hormones, however, as well
as their metabolites, may have several isoforms, some of which are
biologically active while others are inactive. It is also known that
other hormones such as hCG or PMSG, may show a high degree of FSH or
LH activity by bio-assay, which will not be indicated by RIA, due to
the lack of recognition of these hormones by FSH or LH anti-bodies.
Therefore, RIA's for FSH could falsely measure inactive forms as
active, and inversely, fail to measure active forms at all (false
positives and negatives). Our biological analyses measure only these
important bio-reactive molecules, which express FSH and LH activity.
In this way, each vial always contains the same amount of
International Units and the same FSH:LH ratio. Thus, the product is
always the same, and the biological response is more predictable.
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• How is
biological activity measured?
The methods of analysis employed are
the Steelman-Pohley method for FSH, and the Parlow method for LH.
For the assays, prepuberal rats are injected with the compound. To
determine FSH, the increase in ovarian weight is measured after 4
days. To determine LH, depletion of ascorbic acid in the ovary is
measured after 4 hours.
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•
Why are these methods of analysis used?
These methods are the only ones recognised by
the World Health Organisation (WHO) and
European Pharmacopoeia
to measure biological
activity of these two hormones, as they are the most reliable and
specific. They each measure the activity of the hormone, even in the
presence of high concentrations of other compounds, thereby not
interfering with the results. The
Steelman-Pohley method for FSH measures
ovarian growth,
which is the goal of the superovulation.
At a minimum, three replicates of each sample are conducted, in
order to ensure statistical significance of the results and to
develop a parallel-curve, as described in
European Pharmacopoeia.
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•
What dosages should I use?
| Holstein
dairy cows |
800 - 1000 |
IU
|
| Beef
European cows:
|
600 - 800
|
IU |
| Heifers
(dairy, beef): |
500
|
IU
|
| Zebu:
|
250
|
IU
|
| Sheep,
goats: |
250 - 350
|
IU
|
Typically, declining doses of the above total
dosages are administered over a 4 day period at 12 hour intervals,
in addition to a prostaglandin-F2
(PGF2)
on the 3rd
or 4th
day.
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• Recommended schedule for 800
IU in 4 days:
| Day 1
|
08:00 hrs
|
3.0 ml i.m.
|
(150 IU FSH + 150 IU LH)
|
|
20:00 hrs
|
3.0 ml i.m.
|
(150 IU FSH + 150 IU LH)
|
| Day 2
|
08:00 hrs
|
2.5 ml i.m.
|
(125 IU FSH + 125 IU LH)
|
|
20:00 hrs
|
2.5 ml i.m.
|
(125 IU FSH + 125 IU LH)
|
| Day 3
|
08:00 hrs
|
1.5 ml i.m.
|
(75 IU FSH + 75 IU LH)
|
|
20:00 hrs
|
1.5 ml i.m
|
(75 IU FSH + 75 IU LH)
|
| Day 4
|
08:00 hrs |
1.0 ml i.m.
|
(50 IU FSH + 50 IU LH)
|
|
20:00 hrs
|
1.0 ml i.m.
|
(50 IU FSH + 50 IU LH)
|
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•
How many animals can I treat with a package of Pluset?
| - 1 dairy cow |
| - 1.4 beef cows |
| - 2 heifers
|
| - 4 zebus
|
| - 3-4 sheep or goats
|
Since there is more biological activity per unit packaged, more
animals can be treated than with other commercially available
products.
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• Is it important
to adjust the dose?
The cow is a monovulatory specie, thus, it typically ovulates a
single ovum, and is some instances, two. This implies natural
mechanisms of self-regulation through the dominant ovarian follicle,
which normally inhibits the development of other follicles. When
administering gonadotropins, the induced growth of multiple dominant
follicles can significantly alter fertility. Growing follicles
produce estrogens, and can be produced in excess, which can cause
oedema in the oviduct, which can in turn inhibit normal
fertilisation of the oocytes.
Over-stimulation, or excessive ovarian development, is usually
accompanied with poor results, typically characterised by large
numbers on non-fertilised or degenerative ova. To avoid this, the
dose should be reduced to a dose that yields acceptable percentages
of normally developed embryos. Consider that would be preferable to
under-dose than over-dose.
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• Which other
uses does Pluset®
have?
There are some cases of low
fertility due to a deficit in endogenous production of FSH. This can
happen with stressed animals (e.g. - heat-stress), poor or
insufficient feeding, or high milk production. In these cases,
silent heats may occur and ovulation may not be occurring.
The administration of
200 IU of Pluset®
in a single
i.m dose may help to re-establish
ovarian follicular development and ovarian
cyclicity. If the presence of a
corpus
luteum is
detected, PGF2
could be
administered in 3 - 4 days to induce
oestrus and eventual ovulation of the developed follicle.
For any additional information, do not hesitate to contact us
|
Sykes Vet
International
27 Healey Rd
Dandenong Victoria 3164
Australia
Ph +61 3 9706 4913
Fax +61 3 9706 4914
sales@sykes.net.au
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