Scrnario 2 Cancer Flashcards
Pharmacodynamics of lactulose
Lactulose is a synthetic sugar used in the treatment of constipation and liver disease. It consists of the monosaccharides fructose and galactose. In the colon lactulose is broken down primarily to lactic acid and also to small amounts of formic and acetic acids. By the action of via evolved beta galactosidase from colonic bacteria which results in an increase in osmotic pressure and slight acidification of the bcolonic contents. This in turn causes and increase in stool water contents and softens stool.
What is cancer?
Cancer is a group of diseases characterised by unregulated cell growth and the invssion and spread of cells from the site of origin or primary site to other sites of the body
What is breast cancer
Brewer cancer occurs when normal breast tissue cells have undergone several different gene mutations so that the affected cells now grow in a poorly controlled way and can spread locally and to distant parts of the body.
These mutations generally arise in breast epithelial cells (70% from ductal epithelial cells, others from lobular epithelial cells), but very rarely may arise in breasts fat or fibrous connective tissue cells.
Such mutations are caused by genetic or encironental agents or interaction between both
What does ER+ mean?
Some normal body cells have oestrogen receptors and progesterone receptors in their cytoplasm and nucleus eg Brest cells
When oestrogen/progesterone enters these cells, it binds to receptor, is taken to nucleus where it causes part of DNA to become active - this part of DNA increase rate of cell growth/division so activation of these receptors normally stimulates cell growth/division
Explain the implications of knowing that Mary’s tumour is ER+ and/ or explain why Mary is prescribed arimidex
Mary has Brest cancer cells that are oestrogen receptor positive
She could therefore be prescribed a drug which will percent oestrogen from stimulating growth/division of breast cancer cells.
The main source of oestrogen for post menopausal women is by fat calls converting androgens into oestrogen a using the enzyme aromatise.
Aromatase inhibitors stop this production of oestrogen by blocking he action of aromatise
Side effects of arimidex
vaginal bleeding, joint and muscle pain, vaginal dryness, diarrhoea, headaches
Outline the benefits of modified release medication
Won’t have to disturb her
Control pain for a longer time
Pharmacodynamics of morphine
Morphine is an opoid drug. There are already natural opoids int eh body and these are called endogenous opoids which suppres Central controlled pain and therefore blocking the transition of signals from peripherally to the CNS
Morphine mimics this
There are three main opoid receptors: mu, delta and kappa. Mu is thought to be the analgesic effect. Therefore when morphine acts on this it blocks the transmutation of impulses by reducing the excitability of the nociceptors.
When morphine acts on the receptors within the central nervous system this allows MR Muttsy to tolerate more pain than would otherwise be possible. Also the presence of receptors in the limbic system (emotional centre) produces a euphoric or a calming effect. This is of great advantage in a clinical situation m such as when Mary is anxious about her condition and pain. The morphine may also make Mary feel drowsy which may help her rest at the stressful time.
Histamine gets released stimulates the chemoreceptor trigger zone
Pharmacodynamics of cyclizine
Remedies is a protective mechanism for removing irriatant or otherwise painful substances from the upper GI tract. Esmesis is controlled by the vomiting centre in the medulla region of the brain, an important part of which is the chemo trigger zone (CTZ). The vomiting centre possess neurone which are rich in muscarinic cholinergic and histamine containing synapses. Sickness involves overstimulation of these pathways due to various stimuli. Cyclizine blocks the histamine receptors in the vomiting centre thus reducing the activity along these pathways. Furthermore since cyclizine posses anti cholinergic properties as well, the muscarinic receptors are similarly blocked. blocks H1 receptors.
Pharmacokinetics of arimidex
Absorbed: systemic circulation
Distributed: 40 percent protein bound. Adipose tissue and highly perfumed organs, such as liver lung and spleen.
Metabolised: metabolised in the liver (N-dralkylation and glucuronidation)
Excreted 85 percent via heptic metabolism and renal excretion 10 percent
Biovalablilty: 50 percent
Half life: 50 hours
Pharmacokinetics of morphine
Morphine is distributed to skeletal muscle, kidneys, liver, intestinal tract, lungs, spleen and brain. Although the primary site of action is the CNS only small quantities cross the blood brain barrier. Morphine crosses the placental membranes and has been found in breast milk
The primary site of morphine metabolism is the liver, where is undergoes rapid glucuronidation
90 percent eliminated in urine
Protein bound: 30 percent
Bioavailability 30 percent
Half life 3 hours
What are Proco oncogenes and tumour suppressor genes and what do they do?
Proco-oncogene function as the accelerator and non mutant Proco oncogene promote normal cell growth/decision but once mutated (into oncogenes) they are activated so cause uncontrolled growth and division
Tumour suppressor genes function as a brake so normally inhibit/ slow cel growth and proliferation
When mutated they are inactivated so get uncontrolled growth/division
What’s angiogenesis and how does it work?
The development of new blood vessels. Malignant produce a chemical (a cytokine) which is secreted into local environment and causes capillaries to grow more channels so the cancer cells increase its own blood supply so more blood arrives to feed its growing food, 02 requirements etc.
What mutations allow them to grow to a big tumour and I don’t mean metastise
- Prevent the cell from ‘sticking’ to its neighbours, allow cell to detach from its neighbours;
- Enable cell to move - through the local tissues/matrix;
- Stimulate production of enzymes which destroy matrix material and plasma membranes of neighbouring cells (so aiding free movement of the cell);
- Enable cell to enter local lymph channels/capillaries - either by squeezing thru’ or digesting its way thru the capillary/lymph channel wall); Travel in blood stream without being buffeted to death ; Exit at distant site and
- Allow cells to exit capillaries, move thru local area (as above), grow/divide, so building another (secondary/metastatic) tumour site
- Prevent the cancerous cell from dying
Discuss the side effects of morphine
Brain stem so
Reduced consciousness
Respiratory depression
Depressed cough reflex
Limbic system so
Euphoria
Bowel wall nerve plexuses so
Constipation due to decreases stomach emptying and increased water absorption from gut.
Chemo trigger zone
So nausea and vomiting
