Drug Therapy 10% Flashcards
(174 cards)
Which medications need to be biotransformed to their therapeutically active forms before they can exert their principle effects?
Prednisone Azathioprine MMF Cyclophosphamide Leflunomide
What family of enzymes in the liver account for over 70% of drug metabolism in humans?
Cytochrome P450
What factors predict more durable response to intra-articular steroid injections in JIA?
In oligoarticular JIA
Younger patients
Shorter disease duration
How do glucocorticoids work?
They are synthetic analogs of endogenous cortisol and have both anti-inflammatory and immunosuppressive effects.
How do glucocorticoids cause immunosuppression?
Through reduction of circulating T lymphocytes
Affects T > B cells
Affects CD4+ T cells > CD8+ T cells
At what prednisone dose does growth suppression occur?
> = 3 mg/day
What is the most serious, life-threatening complication of chronic glucocorticoid use?
Acute adrenal insufficiency
At risk of vascular collapse, adrenal crisis, death
How does chronic glucocorticoid use cause osteoporosis?
Caused by osteoblast inhibition and apoptosis but also increased bone resorption by inhibition of gut absorption of Ca and increased urinary Ca excretion, potentially resulting in secondary hyperparathyroidism
Where is the most common location for avascular necrosis 2/2 glucocorticoid use?
Femoral head
What are hematologic side effects of glucocorticoids?
Transient lymphopenia and neutrophilia (neutrophil demargination)
What are some features that may help distinguish steroid-induced psychosis from psychosis 2/2 active lupus? (though still hard)
usually acute onset, occurs within 96 hours of initiation of steroids, and are related to high-dose steroids
What muscle fibers are affected by steroid-induced myopathy?
Atrophy of Type IIb myofibers
What are some features of steroid-induced myopathy?
Usually affect proximal muscles, is usually not painful, can have normal muscle enzymes, and EMG suggestive of myopathy
Methotrexate reduces the production of the following cytokines:
TNF, IFN-gamma, IL-1, IL-6, IL-8
How does methotrexate work?
Folic acid analog that is a competitive inhibitor of several enzymes in the folate pathway, including dihydrofolate reductase, TYMS, AICAR transformylase, adenosine deaminase resulting in adenosine accumulation and neutrophil adherence inhibition.
When is methotrexate use contraindicated?
Concurrent use with Bactrim increases risk of cytopenias due to synergistic effects on DHFR
Pregnancy
EtOH use
Renal or liver failure
How does methotrexate exert anti-inflammatory effect?
Adenosine accumulation may contribute to site-specific anti-inflammatory effects of methotrexate through inhibition of neutrophil adherence
Is methotrexate safe in pregnancy?
No. Teratogenic and fetogenic - increased risk of congenital anomalies and pregnancy loss with use during pregnancy.
Is breastfeeding okay in methotrexate?
No, methotrexate secreted in breast milk. Avoid breastfeeding.
What is azathioprine?
A purine analog that is metabolized to 6-mercaptopurine (6MP)
How does azathioprine exert immunosuppressive effect?
Immunosuppression primarily by inhibition of T cell growth during S phase of cell division
What are some relative contraindications to azathioprine?
In TPMT deficient patients
Concurrently with Bactrim
What idiosyncratic reaction can occur in TPMT deficient patients who receive azathioprine?
Arrest of granulocyte maturation
What is pharmacokinetics?
What the body does to the drug