drugs in management of musculoskeletal conditions Flashcards

1
Q

what is pharmacokinetics

A

process by which drug is absorbed, distributed, metabolised and eliminated by the body

ADME

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is bioavailability

A

Degree to which a drug or other substance becomes available to the target tissue after administration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which bones more susceptible to breakage

A

Hip
Wrist
Spine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Although certain groups of people are more likely to break bones such as older people and women this doesn’t mean that their…

A

Ability to repair bone is reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Men are less likely to develop osteoporosis than women but what are they at greater risk of

A

Mortality after a hip fracture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What form osteoclasts and where do they reside

A

Fusion of many circulating monocytes - because many cells fuse together to form osteoclasts means that this cells are multinucleated histologically

Howship lacunae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What gives rise to osteoblasts

A

Arise from differentiation of osteogenic cells in the periosteum. This process requires blood supply otherwise chondroblasts are formed which eventually become chrondrocytes (mature cartilage cells)

Chondroblasts become surrounded by matrix and become osteocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How do osteoclasts resorb bone

A

Attaches to bone via its integrins which are linked to the actin cytoskeleton. Alters the environment through:

  • proton pump on osteoclasts which increases acidity within the sealing zone —> acidic environment = degradation
  • osteoclasts pump in Cathepsins, metalloproteinases and lysosomal enzymes causing breakdown.

Causes release of calcium which is uptaken by osteoclast and then transported out via blood supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How do osteoblasts communicate and control balance of osteoclasts

A

Osteoblasts produces RANKL which upon binding to RANK on osteoclast which will cause maturation

Osteoblast can also produce OPG which will bind to RANKL thus preventing it from binding to RANK preventing maturation of osteoclast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why are women more likely to be affected by osteoporosis

A

Bone density increases until 25

Bone density is maintained between 25-35

After that both males and females lose bone density but this is much larger in females as they have less initially and loss is further exacerbated by hormonal changes during the menopause

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How can MSK disorders be managed

A

Appropriate diet and exercise

Drugs

Replacement of joints

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are bisphsophonates

A

Enzymes resistant analogues of pyrophosphate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does pyrophosphate do

A

Inhibits mineralisation in the bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What property allows bisphosphonates to be specific to the bones

A

Two phosphonat groups are able to bind to calcium and therefore can accumulate readily in bone

BP will also sit in bone until is released by action of osteoclast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the R1 position of the BP associated with

A

Mode of action of the drug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the R2 position of the BP associated with

A

The pharmacokinetics of the drug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the two classes of BP’s

A

Nitrogen containing Bps in the variable R group

Non nitrogen containing BPS in the variable R group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do the two classes of BPs differ

A

Drugs have different potency and different mode of action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Example of nitrogen containing BP

A

Alendronate (contains amine group in R1 region)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Example of non nitrogen containing BP

A

Etidronate (contains methyl group in R1 position)

21
Q

What is the mechanism of action of NNBPs

A

Metabolically incorporated into analogues of ATP that may then inhibit ATP-dependent intracellular enzymes

22
Q

What is the mechanism of action of NBPs

A

Upto a 1000x more potent

Inhibits enzyme that produces molecules needed for post translational modification of GTP binding proteins such as Rab, Rho and Rac.

Above proteins required for actin cytoskeleton and cell motility

In osteoclast action prevents formation of sealing zone thus impairing ability to degrade bone

23
Q

What is the major side effect of BPS

A

Osteonecrosis of the jaw (not that common but is more common in those with bone cancer)

However is still used to treat metastatic bone cancer

24
Q

What are the 3 types of HRT

A
  • oestrogen only
  • mix of progesterone and oestrogen
  • SERMs such as raloxifene
25
Q

What does the action of a SERM depend on

A
  • what subtype of oestrogen receptor is expressed in which tissue. There is an alpha and beta subtype.
  • can also affect receptor dimerisation which is important in cell signalling. Or further downstream can affect binding of co-factors needed for gene expression
  • can directly bind to an oestrogen responsive element
26
Q

How is oestrogen different to SERMS

A

Oestrogen acts as an agonist on breast, uterine and bone tissues so can help alleviate osteoporosis

However with SERMS some can act as agonists whilst others as antagonists

Tamoxifen = antagonist at breast so used to treat breast cancer but acts as an agonist in uterine tissue so may increase cancer risk

Raloxifene = antagonist both in breast and uterus. And agonist at bone

27
Q

What are protective things about HRT

A

Reduced risk of bowel cancer?

28
Q

Bad speculations about HRT

A

Increased risk of cancers in:
- breast
- ovarian
- uterine

29
Q

How does the body normally regulate calcium levels which impacts bone cell activity

A

If too little calcium: parathyroid hormone produced which increases osteoclast activity thus increasing calcium release into blood. Bone resorption increases

If too much calcium = thyroid produces calcitonin which inhibits calcium reabsorption in gut and kidney. Also initiates osteoblasts activity

30
Q

Possible treatments for RA

A
  • NSAIDS tackle pain aspect
  • DMARDS
  • steroids
  • biological agents
  • immunosuppressive drugs
31
Q

Mechanism of action of NSAIDs

A

Target COX enzyme which converts arachidonic acid into prostaglandins, prostacyclin and thromboxanes. (PGl2 protective effect on stomach lining)

COX-1 driven by physiological stimuli
COX-2 driven by inflammation.

Coxibs specifically target COX-2 such as celecoxib. Developed to reduce stomach issues with use of aspirin.

32
Q

Name of coxib and elevated risk of what..

A

Celecoxib

CVD

33
Q

Mechanism of action of steroids such as prednisolone

A

Steroids = lipid based compounds that bind to their nuclear receptors in cytoplasm. Move to nucleus and exert effects on gene expression

Reduce gene expression of genes associated with inflammation such as cytokines, COX expression.

Increase expression of anti-inflammatory genes

34
Q

Long term side effects of steroid use

A

Cushing syndrome.

35
Q

What conditions is Cushing syndrome associated with

A

Increased intraocular pressure
Cataract
Benign intracranial hypertension
Aseptic necrosis of femoral head
Osteoporosis
Pancreatitis

36
Q

What does DMARD stand for

A

Disease modifying anti rheumatic drugs

37
Q

Examples of DMARDS

A

Low dose methotrexate

Pencillamine

Suplhasine

Chloroquine

38
Q

Mechanism of action of methotrexate

A

Normally taken as anti-cancer drug

Prevent purine biosynthesis ( A + G ) and production of RNA

When given as low dose reduces activity of immune cells and their production

39
Q

Who should not receive methotrexate even at a low dose

A

Pregnant women as it is teratogenic

40
Q

What is sulphasine

A

Pro drug - takes a while to have therapeutic effect

Contains sulfur atom so not well tolerated by some patients

Affects fertility with reduced sperm count

41
Q

Mechanism of action of chloroquine

A

Traditionally an anti-malarial drug.

Changes antigen presenting in the immune system

42
Q

What are biological therapies

A

Use of antibodies to target cytokines such as TNFalpha

43
Q

Examples of biological therapy drugs

A

Etanecerpt

Infliximab

Adalimumab

44
Q

Why are global immunosuppressants problematic

A

On a systemic scale reduce activity of the immune system thus increases individuals risk of infection

45
Q

Examples of immousuppressants

A

Cyclophosphamide

Cyclosporine

46
Q

As cyclophosphamide is toxic why should regular blood tests be carried out

A

Can lead to neutropenia and suppression of haemotopoeisis

47
Q

Which dmard reduces fertility by reducing sperm count

A

Sulfasalazine

48
Q

How long does sulfasalazine take to work

A

2-3 months