DMARDS Flashcards
What does DMARDS stand for?
Disease modifying anti-rheumatic drugs
What are the aims of therapy of DMARDS?
They are immuno-suppressant drugs that according to NICE aim to influence the course of a disease (halt or reverse progression of an auto-immune disease)
What are the three classifications of DMARDS within some examples?
Conventional DMARDs: this includes methotrexate, sulfasalazine, hydroxychlorquine
Biological DMARDs: Adalimumab and Rituximab
Synthetic/targeted DMARDs: Tofacitinib (JAK inhibitor) and Apremilast
Who normally initiates the use of DMARDs?
Secondary care (consultant with additional training in a specialised area) although GPs may be involved in the monitoring of a patient once they are commenced on a DMARD regime.
What conditions often have DMARDs prescribed?
Widely used in the treatment of Rheumatoid arthritis in addition to:
Ankylosing spondylitis
Connective tissue diseases
Psoriasis
Psoriatic arthritis
Vasculitis
Inflammatory bowel disease
Briefly describe the mechanism of methotrexate.
Methotrexate is an inhibitor of dihydrofolate reductase - an enzyme crucial for the metabolism of folic acid required for the production of purine and thymidylate synthase crucial for nucleic acid synthesis. This mechanism correlates to Methotrexate’s cytotoxic activity indicated for neoplasia. However Methotrexate’s indication for auto-immune diseases is not related to this mechanism but instead is believed to link to being an adenosine uptake inhibitor resulting in adenosine accumulation.
What are the three structural elements of folates which correlate with the structure of methotrexate?
A pteridine ring, p-aminobenzoic acid and glutamic acid
Can methotrexate cross the blood brain barrier?
No as the drug has low lipid solubility
Aside from methotrexate’s cytotoxic activity mechanism, describe the effects the drug has on T cells in the application of rheumatoid arthritis.
Methotrexate is known to reduce the production of pro-inflammatory cytokines crucially reducing the synthesis of IL-2 and the expression of the IL-2 receptor on CD4+ T cells or Th1 cells hence this reduces the activation of the T cells resulting in a further decreased activity of osteoclasts and fibroblasts which normally activate metalloproteinases which leads to the erosion of the bone and cartilage.
How is methotrexate uptaken into cells and metabolised?
By the folate transport system and is metabolised to polyglutamate derivatives, which are retained in the cell for weeks or months even in the absence of extracellular drug.
Is Ciclosporin orally bioavailable?
Despite not following Lipinski’s rules, Ciclosporin is orally bio-available due to having a balance of hydrophobicity and hydrophilicity which enables it to be able to cross the gut membrane.
What is the main metabolism of Ciclosporin?
CYP 450
Describe the structure of ciclosporin.
It is a cyclic peptide of 11 amino acid residues - some of the amino acids are not found in animals
Describe the activity of ciclosporin.
Ciclosporin has immunosuppressent activity but it doesn’t have an effect on the acute inflammatory response.
It does not have cytotoxic activity like methotrexate.
What are the four ways ciclosporin is an immuno-suppressant?
Inhibits IL-2 synthesis and the expression of IL-2 receptors which leads to decreased T cell proliferation
Reduced induction and clonal proliferation of cytotoxic T cells from CD8+ precursor T cells
Reduced function of the effector T cells responsible for cell-mediated responses (e.g. decreased delayed-type
hypersensitivity)
Some reduction of T cell-dependent B-cell responses
When does the peak plasma concentration of ciclosporin occur?
Within 3-4 hours of administration
What is the half life of ciclosporin?
24 hours
Describe the distribution of ciclosporin in the body.
Ciclosporin accumulates in the tissue at a concentration 3-4 times greater than its accumulation in the plasma. Most of the drug remains in the lymphomyeloid tissue and fat deposits long after the administration of the drug has stopped.
Describe the pharmacokinetics of Leflunomide.
-It is orally active and well absorbed from the GI tract.
-It has a long plasma half-life which increases its risk of cumulative toxicity
-The active metabolite undergoes enterohepatic circulation.
Describe the mechanism of Leflunomide.
It has not yet being fully determined however it is believed that the drug regulates the autoimmune lymphocytes by interfering with its cell cycle progression. It inhibits the enzyme dihydroorotate dehydrogenase (a mitochondrial enzyme involved in de novo pyrimidine ribonucleotide uridine monophosphate (rUMP)synthesis) and has antiproliferative activity.
What are the indications of Ciclosporin A?
Irritable bowel disease
Immunosuppressive therapy in transplant patients
Psoriasis
Severe atopic dermatitis
Rheumatoid arthritis
What are the formulations of Ciclosporin?
Oral capsules or IV
What formulation is prescribed is dependent upon the indication
What are the initial administrative requirements for Ciclosporin?
The dose of Ciclosporin should be up titrated according to effective balanced against the patient tolerability to the drug (side effects and close monitoring).
What are the most common side effects of Ciclosporin?
Headache
Tremor
Hypertension
Hiruitism
Renal impairment
What are the fairly common side effects associated with Ciclosporin?
GI disturbances
Fatigue
Convulsions
Muscle cramps
Myalgia
Leukopenia
Hepatic impairment
Hypertrichosis
What are the effects Ciclosporin has on U & Es?
Hyperglycaemia
Hyperlipidemia
Hyperkalemia
Hyperuricaemia
Hypomagnesia
When is it more likely a patient will experience side effects associated with Ciclosporin?
When the patient is taking a high dose of the drug for a long period of time
What type of cancers is Ciclosporin associated with?
Lymphoma and skin malignancies
Therefore it should be recommended to the patient to avoid/limit UV exposure such as sunlight
What are the contra-indications of Ciclosporin?
Renal impairment
Malignancy
Uncontrolled hypertension
Uncontrolled infection
(All due to potential side effects of the medication)
What infections may you want to screen for before initiating the patient on Ciclosporin therapy?
Latent or active TB
Hepatitis
Varicella Zooster
When should Ciclosporin be cautioned and why?
In the elderly - due to already reduced renal and hepatic function in this population, causing them to be increasingly susceptible to experiencing these side effects. Elderly patients tend to have a higher blood pressure also
Patients with gout- exacerbation due to side effect of hyperuricaemia
Hepatic impairment - will require a dose adjusted as the drug is CYP450 metabolised and excreted from the biliary
What are the toxic monitoring parameters for Ciclosporin?
Renal function
Hepatic function
Blood pressure
Lipids
Electrolytes - potassium and magnesium
Uric acid
In an non transplant patient how often should the toxic monitoring parameters of Ciclosporin be measured?
In non-transplant patients, occasional monitoring of ciclosporin blood levels is recommended.
This could be when Ciclosporin is co-administered with substances that may interfere with the pharmacokinetics of ciclosporin, or in the event of unusual clinical response (e.g., lack of efficacy or increased drug intolerance such as renal dysfunction).
What classes of drugs does Ciclosporin interact with?
Ciclosporin relies on CYP450 for its metabolism and therefore plasma concentrations of Ciclosporin can be increased (by CYP450 inhibitors) or decreased (by CYP450 inducers) by drugs of that class.
What are some examples of drugs that are CYP 450 inhibitors?
Drugs that will increase the concentration of Ciclosporin:
Macrolides - Clarithromycin
Dilitazem
Verapamil
Lercandipine
Fluconazole, Itraconazole, Ketoconazole
Grapefruit juice
What are some examples of drugs that are CYP450 inducers?
Drugs that will decrease concentrations of Ciclosporin:
Rifampicin
Carbamazepine
Phenobarbital
Phenytoin
St Johns Wort
What is the risk of prescribing Ciclosporin with statins?
Should be avoided or dose reduction
This is due to Ciclosporin increasing the exposure of Statins as it is a CYP3A4 inhibitor. This increases the potential for adverse events such as myopathy and potentially rhabdomyosis
When should Statin therapy be with held?
Statin therapy needs to be temporarily withheld or discontinued in patients with signs and symptoms of myopathy or those with risk factors predisposing to severe renal injury, including renal failure, secondary to rhabdomyolysis
What are some of the other drug interactions with Ciclosporin?
Drugs that also exhibit Nephrotoxic synergy
NSAIDs
Aminoglycides
Fibric acid derivatives
H2 antagonists
Methotrexate
Drugs that have similar side effects
Potassium sparing diuretics
If Ciclosporin is prescribed alongside a drug that has the potential to cause Nephrotoxicty what pharmaceutical care considerations should be made?
Increased renal function monitoring
Discontinue if renal function drops
Describe the difference in bioavailability between oral and IV Ciclosporin?
Oral dose is approximately 3x that of the IV dose
Are brands interchangeable of Ciclosporin?
In both transplant and non transplant patients, switching brands of Ciclosporin is not recommended unless done under supervision of prescriber.
Is dose monitoring required more intensely for transplant or non- transplant patients?
Transplant patients require more frequent monitoring especially when there is a dose alteration.
How should the oral solution of Ciclosporin be diluted?
With orange or apple juice
Not grapefruit juice