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The present invention relates to the treatment of arthritic and like
complaints.
The term "arthritic" is used medically to describe the occurrence of
inflammation of a joint. Arthritis exists in many forms; rheumatoid
arthritis is a chronic form of arthritis where many joints are affected
and the inflammation is often such that gross deformity and immobility of
the joint may result. Rheumatoid arthritis has, in the past, been treated,
for example, with cortisone or with non-steroidal anti-inflammatory drugs.
Cortisone is effective in combating inflammation but also carries with its
use a high risk of dangerous side effects. Treatment with non-steroidal
anti-inflammatory drugs (NSAID's) has often been found not to be as
effective as desired to reduce inflammation. The most popular NSAID is
aspirin which has to be used in very high doses e.g. 16-18 tablets per
day.
It has been previously found that in cases of rheumatoid arthritis there is
a low blood plasma iron level but a high amount of iron in the synovial
membrane which is stored as ferritin in synovial reticuloendothelial
cells.
It has been found that the inflammation of joints mainly in rheumatoid
arthritis is exacerbated by the production of free oxygen radicals
generated in the presence of catalytic free iron, as opposed to ferritin.
Desferrioxamine is an iron-chelating agent which has long been used in the
treatment of iron poisoning and which has also been used extensively in
the examination of iron metabolism in many diseases including rheumatoid
arthritis. We are not aware, however, that the use of desferrioxamine to
reduce the inflammation in the treatment of rheumatoid arthritis has ever
been disclosed.
We have surprisingly found that the treatment of rheumatoid arthritis and
like diseases by the administration of desferrioxamine over a prolonged
period in a suitable dosage gives remarkable reduction in the inflammation
of joints. This is all the more surprising when it is realised that small
or short term administration of the compound exacerbates the inflammatory
condition.
Without wishing to be bound by any theory as to the mechanism of action of
desferrioxamine within the body, it is thought that the excess iron stored
as ferritin in the reticuloendothelial cells and the free iron in the
synovial fluid exist in an equilibrium such that any chelation of the free
iron on a short term basis disturbs the iron balance and causes the
production of large amounts of free iron from the stored ferritin possibly
even overcompensating for the loss of the free iron; the free iron then
causes exacerbation of the joint inflammation as indicated above, and it
is perhaps for this reason that where desferrioxamine has been used
hitherto in studies of iron metabolism that indications have been that it
would not be useful for the treatment of rheumatoid arthritis. Prolonged
treatment with desferrioxamine is thought, however, to gradually "mop up"
the free iron produced and to reduce the amount of free iron available for
catalysts giving rise to a reduction in inflammation.
Accordingly, the present invention provides a method of treatment of
rheumatoid arthritic and like diseases involving joint inflammation, which
comprises administering desferrioxamine in a therapeutically effective
dosage over a prolonged period.
The method of the invention may be applied to the treatment of non-specific
monoarthritis and any other instances of joint inflammation caused by free
iron catalysis. The method of the invention may also be applied to any
other complaint which is induced by the occurrence of free iron, for
example certain instances of myocardial infarction as recently suggested.
The amount of desferrioxamine administered is suitably a therapeutically
effective amount in the range of from 1 to 10 g per day, for example 1 to
5 g per day, suitably 2 to 3 g per day.
The present invention also provides a pharmaceutical preparation suitable
for intra-articular administration which comprises desferrioxamine in
admixture or conjunction with a pharmaceutically suitable carrier.
The present invention further provides a pharmaceutical preparation in the
form of a pack which contains a support member together with a plurality
of dosage forms comprising desferrioxamine, preferably enough for 3 weeks'
supply.
Suitably the amount of desferrioxamine present in each dosage form in a
pack of the invention is in the range of from 1 to 10 g, e.g. in the range
of from 1 to 5 g, conveniently 2 to 3 g. The amount of desferrioxamine may
be different in each dosage form, for example a pack may comprise a set of
dosage forms one containing 1 g of desferrioxamine, another 2 g of
desferrioxamine and so on to 5 g, 7 g or 10 g of desferrioxamine. The
desferrioxamine is suitably present in lyophilised powder form as
desferrioxamine mesylate but may be in a liposome formulation.
Desferrioxamine may be administered by any one of several routes.
Administration intravenously, intra-peritoneally, subcutaneously,
intra-muscularly or intra-articularly by infusion solution are all
suitable routes, intra-articular and subcutaneous infusion being
preferred. Administration by infusion solution may be by continuous pump
administration or administration in divided doses, i.e. twice or three
times daily, daily, weekly or monthly. The active substance may be present
in the infusion solution prior to the start of the administration or may
be injected in as a "bolus" concentrate. Other routes of administration
possible are via the skin or by the use of a liposome formulation.
Administration via the skin may be by the transdermal "delivery system"
(Alza Corporation) where medication externally applied by means of a
special applicator reaches the affected joint by absorption through the
skin. Direct topical administration may occur from once to four times
daily by means of an ointment or cream containing desferrioxamine.
Preparations containing desferrioxamine may in addition contain the usual
carriers, excipients and auxiliaries. In infusion solutions, for example,
pH-regulating substances, e.g. sodium phosphate and substances imparting
isotonicity to the solutions, e.g. sodium chloride, may be present.
The period of administration of desferrioxamine will vary depending on the
severity of the disease, but is usually at least 5 days. In chronic cases
the administration may occur initially over a period of 3 weeks to a month
with the treatment being repeated at 3, 6 or 12 month intervals or sooner
if chronic inflammation occurs or recurs. In instances of subcutaneous
administration by infusion solution, it has been found satisfactory for
the initial 3 week treatment to consist of continuous administration over
several hours daily for 5 consecutive days, followed by no administration
for 2 days and then repeat treatment for the following 5 days and so on.
The above methods of administration are acceptable methods for introducing
desferrioxamine into the body but cannot ensure that all of the active
substance reaches the site of the free iron and ferritin stores in the
reticuloendothelial stores. Also the most useful preparations, the
infusion solutions, have to be made up shortly before use from lyophilised
desferrioxamine powder because aqueous desferrioxamine solution is
unstable over periods of longer than a week.
The present invention also provides a method for the treatment of
rheumatoid arthritis, wherein a pharmaceutical preparation comprising
desferrioxamine as a liposome formulation is administered to the patient
orally or parenterally. Liposomes are lipoid vesicles of varying sizes
which encapsulate an active ingredient. The lipoid walls may comprise one
or more lipid bi-layers. Suitable lipids are phospholipids; they may be
used in pure form or in combination with other suitable substances.
Desferrioxamine in aqueous solution may be incorporated into liposomes
which have an avidity for the reticuloendothelial cells without apparent
loss of stability. With such a formulation the desferrioxamine may "home
in" on the reticuloendothelial cells and it is believed that such
formulations will enable smaller amounts of desferrioxamine to be
administered for the same anti-inflammatory effect because the active
substance is retained in the liposomes until the site of action is
reached. Liposomes may be administered by enteral or parenteral means,
preferably by intra-articular injection or by oral administration.
Suitably each liposome formulation may contain in the range of 0.1 to 12.5
mg of desferrioxamine.
Administration of desferrioxamine when entrapped in red cell ghosts is also
possible to counter inflammation.
Desferrioxamine has been found to give a significant reduction in joint
inflammation in patients suffering from rheumatoid arthritis without any
apparent side-effects. It has also been found to give such results when
used in conjunction with non-steroidal anti-inflammatory drugs without any
apparent undesirable interactions. Desferrioxamine may thus be used as a
replacement for or as a supplement to the non-steroidal anti-inflammatory
drugs already used.
The following Examples illustrate the invention.
Desferrioxamine Preparations
I. Infusion Solutions
(a) The contents of an ampoule containing 500 mg of lyophilised
desferrioxamine (commercially available under the trade name Desferal in
the form of lyophilised desferrioxamine mesylate) were completely
dissolved in 2-3 ml of Water for Injection BP and then made up to the
required amount with a suitable infusion solution. An infusion solution
containing 1 g of desferrioxamine was similarly prepared using 2 ampoules
as above. Also solutions containing 2 g (using 4 ampoules), 3 g (using 6
ampoules), 5 g (using 10 ampoules), 7 g (using 14 ampoules) and 10 g
(using 20 ampoules) of desferrioxamine. Suitable infusion solutions are
normal saline, dextrose, dextrose saline, blood and Ringers Lactate
solution.
(b) 1 g of desferrioxamine was dissolved in 10 ml of Water for Injection BP
to give a 10% solution of desferrioxamine. Sufficient sodium chloride to
render the solution isotonic was added. Such a solution may be diluted
with suitable infusion solutions (as mentioned above) or may be used as a
concentrated or "bolus" solution.
II. Ointment
An ointment containing 5% by weight of desferrioxamine based on 0.4% of
cetyl alcohol, 4.6% of wool fat, 65% of white soft paraffin and 30% of
liquid paraffin, was prepared by known procedure comprising heating the
cetyl alcohol, wool fat, white soft paraffin and liquid paraffin together
and incorporating the desferrioxamine.
III. Liposomes
The liposomes were prepared with a mixture of dipalmitoyl
phosphatidylcholine, cholesterol and stearylamine, in a molar ratio of
3.6:2.3:1 respectively, dissolved in chloroform. This mixture was dried in
a round bottom flask in a rotary evaporator. The flask was placed in a
37.degree. C. water bath and 1 ml of a 10-12% aqueous solution of
desferrioxamine mesylate was slowly added to the flask with immediate and
constant stirring with a magnetic stirrer. The resultant suspension of
liposomes containing desferrioxamine was centrifuged at 2000 rpm for 5
minutes. The supernatant was carefully pipetted off and the liposome
pellet was suspended in normal saline. The centrifugation and resuspension
procedure was repeated five times to ensure the complete removal of
nonencapsulated desferrioxamine solution. For injection, the liposomes are
to be resuspended in saline.
Other liposome preparations were prepared by similar known methods using
the lipoid mixtures given below. The abbreviations noted designate the
following compounds:
CH=cholesterol
DP=dicetyl phosphate
DMPC=dimyristoyl phosphatidylcholine
DOPC=dioleoyl phosphatidylchloline
DPPC=dipalmitoyl phosphatidylcholine
PA=phosphatidic acid
PC=egg phosphatidylcholine
PCA=egg phosphatidic acid
PS=phosphatidylserine
SA=stearylamine
Unless specifically stated, the solvent used for the lipoid mixture was
chloroform.
1. 6 mg DPPC and 3 mg PCA in 1.25 ml chloroform.
2. 22.5 mg PC and CH in 10-15 ml chloroform
PC and PA in a molar ratio of 7:1
4. PC, CH and PA in a molar ratio of 7:2:1
5. PC, CH and SA in a molar ratio of 7:2:1
6. PC, CH and DP in a molar ratio of 7:2:1
7. PC, CH and PA in a molar ratio of 7:5:1
8. PC, CH and SA in a molar ratio of 7:5:1
9. DOPC, CH and PA in a molar ratio of 7:5:1
10 DMPC, CH and PA in a molar ratio of 7:5:1
11. PC and CH in a molar ratio of 8:2
12. PC and CH in a molar ratio of 9:2
13. DPPC, CH and PA in a molar ratio of 7:2:1
14. PC, CH and PS in a molar ratio of 7:2:1
The size of the liposomes was varied in certain cases from multilamellar
liposomes to unilamellar liposomes by ultrasonication.
Animal Tests
Inflammation of joints was induced by various recognised methods as
indicated below and the effects of administered desferrioxamine were
studied.
I. Induction by ureates
Crystal ureate was used to induce footpad swelling in rats. 1 mg, 10 mg, 30
mg and 60 mg doses of desferrioxamine per kg were administered, each to
different rats, and the footpad swelling was measured after 2 and 24
hours.
The rats which had received the 1 mg/kg and 10 mg/kg doses exhibited
significantly increased swelling of the affected footpad whilst the higher
doses showed a marked anti-inflammatory effect with reduced swelling.
II. Induction by carrageenan
Carrageenan was used to induce footpad swelling in rats. Two doses of
desferrioxamine were studied: 1 mg/kg and 60 mg/kg. The 1 kg/kg dose
exhibited no effect on the footpad swelling whilst the 60 mg/kg dose
significantly reduced the footpad swelling.
III. Induction by Bovine Gamma Globulin (BGG)
The Glynn-Dumonde model of adjuvant arthritis was followed which involves
the injection of BGG in Freunds complete adjuvant to instigate
inflammation followed by a second injection of BGG after 10 days to
maintain the induced swelling.
50 mg/kg of desferrioxamine were administered to one group of rats at the
time of the second injection and the same amount was administered to a
second group of rats on days 7 to 14.
The dose on day 10 exacerbated the arthritis whilst that on days 7 to 14
exhibited a reduction in the inflammation of the adjuvant arthritis each
compared to a control group of rats to which no desferrioxamine was
administered.
IV. Induction by mycobacteria
Adjuvant arthritis was induced by mycobacteria. 30 mg/kg of desferrioxamine
were administered to a first group of rats on each of the first 5
consecutive days after induction. A reduction in the primary lesions over
a group of control rats was noted. 30 mg/kg of desferrioxamine were
administered to a second set of rats on each of the 15th to 19th days
after induction and note was taken of the effect on secondary lesions. The
second set of rats had reduced secondary lesions over the control rats and
also over the first set of rats which now exhibited worse secondary
lesions than the control rats.
Tests on Humans
1. One patient with non-specific monoarthritis of the knee received 5 daily
injections of desferrioxamine intra-articularly after synovial fluid
aspiration. Doses of desferrioxamine were increased daily until on days 4
and 5 the patient received 1 g of desferrioxamine (injected over 1 hr).
The total dose of desferrioxamine injected was 3.5 g.
Results
(a) No local or systemic side effects were observed.
(b) There was a noticeable reduction of the swelling of the knee which
continued for 3 months after the injection (longer relief than had
previously been experienced).
(c) Synovial fluid showed reduction of catalytic iron and thiobarbituric
acid reactivity.
(d) Synovial fluid ferritin levels were reduced, but no changes were found
in the serum.
(e) In 3 hours after injection there was marked leucocytosis in the
synovial fluid.
2. Nine patients with active rheumatoid arthritis received 1 g of
desferrioxamine daily for 3 weeks (treatment on 5 days a week only) by
subcutaneous infusion over 7 to 8 hours. All patients were admitted to the
hospital for the time of the trial. Treatment with non-steroidal
anti-inflammatory drugs was continued throughout the trial.
The following clinical and laboratory parameters were evaluated at weeks 1
and 3:
Ritchie index, morning stiffness, grip strength, VAS pain scores, FBC, ESR,
rheumatoid factor, immunoglobulins, iron, thiobarbituric acid reactivity.
Results
No changes in the laboratory parameters were found; however, thiobarbituric
acid reactivity was reduced in some patients studied. Clinical indices of
disease activity showed improvement at week 3 (8 patients out of 9)
despite, after 1 week of treatment, 8 out of 9 patients having experienced
flare-up of their arthritis and 1 patient having developed vasculitis
(this cleared after the 3 weeks of treatment).
No side effects were reported.
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