Mata Flashcards
Erythocyte factors
Iron
Vitamins B12 and folate
EPO
Granulocyte factors
Filgastim (g-CSF)
Sargramastim (GM-CSF)
Platelet factors
Oprelvekin (IL11)
Romiplostim
Eltrombopag
Most common causes of iron and vitamin diff.
- menstruation in females
- drug treatment w/ NSAIDS (blood loss)
- pathological conditions
- parasitic infestation.
- Pregnancy and child bearing
Iron uptake
Abs in duodenum/proximal jejunum
Give at 2 hrs before or 4 hours after food
Do not give with phosphates/phyates/tannates
Abs. better with Acids
- Iron dextran– Low (InFeD®) and high (DexFerrum®) MW
IV/IM bolus or IV infusion (for large doses)
Because of allergic reactions a test dose infusion can be performed when giving this agent for the first time.
Indications Excessive continuing blood loss Inflammatory bowel disease Chronic kidney disease Use in cancer patients Use in heart failure
- Ferric Gluconate Complex (Ferrlecit®)
Commonly used with EPO
1 hr IV infusion, lower incidence of hypersensitivity reactions than HMW dextran
The potential exists for fatal hypersensitivity reactions and test doses are recommended in patients with drug allergies including iron dextran.
- Iron Sucrose (Venofer®)
safe and effective for many conditions that require parental iron supplementation
rountinely used in combination with erythropoietin during hemodialysis to prevent Fe deficiency anemia from loss of RBC during dialysis + RBC production.
Unlike other parental formulations iron sucrose is not used for total dose infusions and is limited to 300 mg every 2-3 weeks.
total dose infusions – repeleting iron stores with a single treatment episode
Ferumoxytol (Feraheme®)
composed of superparamagnetic iron oxide nanoparticles coated with a low molecular weight semisynthetic carbohydrate.
It has been deemed safe and effective when given as a rapid intravenous infusion (> 1 min) in patients with chronic kidney disease (CKD) and those on dialysis.
. Ferric carboxymaltose (Ferinject®)
is a novel stable iron complex for intravenous use that can be given at single doses of up to 1000 mg of elemental iron per week over a recommended infusion time of 15 minutes.
Approved in July 2013 up to 1500 mg of iron can be administered over the course of two treatment sessions.
Side effects of IV iron
Self-limiting fever, arthralgias, and myalgias, usually within 24 hours of infusions. These resolve without therapy but a small clinical benefit is obtained from the use of nonsteroidal anti-inflammatory agents.
A flare of arthritis in patients with inflammatory arthritis, such as rheumatoid arthritis, commonly occurs. (steroids?)
Chelation therapy for iron toxicity
Treatment for acute toxicity: deferoxamine
Treatment of chronic toxicity: deferoxamine or deferasirox
Vitamin B12= Cyanocobalamin
- B12 is complexed w/ intrinsic factor and absorbed via a highly selective receptor-mediated transport system.
- Transcobalamin II – systemic transport
B12 is maintained as two important active coenzymes
a) Methylcobalamin: utilized for synthesis of methionine from homocysteine
b) Deoxyadenosylcobalamin: responsible for carbohydrate and lipid metabolism
B12 vs intrinsic factor anemias
B12- Megaloblastic (RBC first) and can have irrreversible neuro damage characterized by swelling of myelinated neurons, demyelination and cell death in spinal chord & cortex
Intrinsic- Pernicious
B12 drugs
Hydroxocobalamin (Generic) – IM Only
Cyanocobalamin (Generic) – IM /Deep SQ
Intranasal Gel (Nascobal)
Can also supplement folate to correct B12 problem but not resolve myelination problem
Folic acid
Used in myelination and in DNA synthesis
• DEFICIENCY Megaloblastic Anemia indistinguishable from that caused by B12 deficiency.
• ANEMIA will appear more rapidly with folate deficiency than with B12 deficiency because there is a limited storage pool.
• Folic acid DOES NOT lead to neurological abnormalities
• Higher strengths + injectable require prescription
Erythropoietin - a.k.a. Epoetin Alfa or EPO (Epogen
Erythropoietin binds to the erythropoietin receptor (EpoR) on red cell progenitors and precursors and promotes survival and proliferation.
Titrate dose to prevent too rapid ↑ in Hct .
Patients must have adequate Fe in circulation before therapy initiated
Rapid expansion of red cell mass can ↑ blood volume & viscosity leading to↑ vascular resistance.
Erythropoietins increase the risk of death, myocardial infarction, stroke, venous thromboembolism, thrombosis of vascular access and tumor progression or recurrence
Made in kidney
Three formulations all given by injection IV or SC
- Erythropoietin - a.k.a. Epoetin Alfa or EPO (Epogen®) Recombinant form of erythopoietin 3x / week
- Darbepoetin alfa - (Aranesp®) 1x/week
- Methoxy polyethylene glycol-epoetin - (Mircera®) 1-2X/month
Uses:
Anemias, particularly those associated with chronic renal failure (CRF).
Adjunct to drugs therapies that cause bone marrow suppression & anemias.
(e.g. zidovudine to AIDS patients, granulocytopenia and anemia, cancer chemotherapy related bone marrow supression and anemias.
During elective non-cardiac/non-vascular surgery to ↓ need for transfusions
Filgrastim
Two preparations: natural and PEG compound
granulocyte colony stimulating factor, G-CSF
Stimulates proliferation of progenitor cells committed to the neutrophil lineage
Activates neutrophil phagocytic activity
Prolongs their lifetime
Mobilize hematopoietic stem cells
Longer duration, injected once every few weeks
Filgrastim binds to the G-CSF receptor and stimulates the production of neutrophils in the bone marrow. It controls proliferation of committed progenitor cells and influences their maturation into mature neutrophils. Filgrastim also stimulates the release of neutrophils from bone marrow storage pools and reduces their maturation time.
Pegylation reduces clearance via glomerular filtration, cleared via NEUTROPHILS ONLY
Granulocyte Colony-stimulating Factor (G-CSF)
USES: To Treat severe neutropenia following:
1. Autologous marrow transplants ↓ morbidity due to bacterial/fungal infections
2. Cancer chemotherapy. ↓ hospitalization for febrile neutropenia.
3. Severe congenital neutropenia.
4. Neutropenia in AIDS patients on zidovudine
SIDE EFFECTS:
• Bone pain (mild-moderate)
• Local skin reactions if given S.C.
• Prolonged treatment can marked GRANULOCYTOSIS that resolves with cessation of treatment.
Myeloid Growth Factors
Sargramostim - granulocyte-macrophage colony stimulating factor, GM-CSF
Broader stimulatory activity
Similar Neutrophil stimulatory activity
Sargramostim binds to the Granulocyte-macrophage colony stimulating factor receptor (GM-CSF-R-alpha or CSF2R) which stimulates a JAK2 STAT1/STAT3 signal transduction pathway. This leads to the production of hemopoietic cells and neutrophils.
Pegylation reduces clearance via glomerular filtration, cleared via NEUTROPHILS ONLY
SARGRAMOSTIM (Leukine
Acts similar to G-CSF but with broader spectrum.
USES:
1. Autologous marrow transplants to shorten duration of neutropenia ↓ morbidity
2. Shorten neutropenia & ↓ morbidity in chemotherapy & AIDS-related neutropenia.
3. Effective in some patients with aplastic anemia or myelodysplasia.
SIDE EFFECTS
HIGHER DOSES Bone pain / malaise / fever / diarrhea / dyspnea / rash.
1ST Dose Acute Reaction: reaction to first infusion (may include face flushing, trouble breathing, dizziness)
Oprelvekin (Neumega®)
– recombinant form of endogenous cytokine IL-11.
• MOA: Stimulates the growth of primitive megakaryocytic progenitors, Increases peripheral platelets and neutrophils
• Clinical Use: Thrombocytopenia and reduces the need for platelets.
• Side Effects: fatigue, headache, dizziness, and cardiovascular effects.
• Major Complication – FLUID RETENTION (indicative of peripheral edema or dyspnea on exertion) CAUTION if CHF.
ROMIPLOSTIM (Nplate®)
new therapeutic class “peptibodies”. Genetically engineered protein in which Fc components of a human antibody are fused to multiple copies of a peptide that stimulates the thromboplastin receptors.
ELTROMBOPAG (Promacta
Orally active thromboplastin receptor agonist.
• SIDE EFFECT: ability to cause HEPATOTOXICITY and HEMORRHAGES
Nucleoside Reverse Transcriptase Inhibitors
- NRTIs must first undergo intracellular phosphorylation to be active
- NRTIs inhibit the viral reverse transcriptase enzyme (Enzyme responsible for transcribing viral RNA into double stranded DNA)
- NRTIs mimic other nucleosides and are incorporated into the DNA strand
- They prevent the addition of the natural nucleosides into the DNA strand
- This halts the production of new virions
Some of the more common NRTI’s
Zidovudine (AZT)
Tenofovir (already phosphorylated)
Abacavir
Mainly undergo renal excretion EXCEPT
Zidovudine (AZT) undergoes glucuronidation
Abacavir (ABC) metabolized by alcohol dehydrogenase
Do not have P-450 drug interactions
Highly active antiretroviral therapy (HAART) toxicity
NRTI-related mitochondrial toxicity, which manifests as serious side effects such as hepatic failure with steatosis and lactic acidosis
NRTI’s resistance
Can descriminate
Can remove
Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
Nevirapine (NVP, Viramune™)
Delavirdine (DLV, Rescriptor™) rarely used
Efavirenz (EFV, Sustiva™) Most potent
Advantage: long half life
Disadvantage: Greater risk of resistance at the time of treatment leading to failure than with PIs
Potential for cross resistance
Skin rash
Transmitted resistance more common than with protease inhibitors.
Single mutation confers cross resistance to all available NNRTIs
Metabolism
Hepatic metabolism by cytochrome P450s
-no renal dosage adjustments required
Adverse Reaction with NNRTIs:
Efavirenz
CNS adverse effects, such as abnormal dreams, dizziness, headache, and depression, which usually resolve.
Protease Inhibitors
End with Navir
Advantages:
Higher genetic barrier to resistance than NNRTIs and Integrase inhibitor (Raltegravir)
PI resistance at the time of treatment failure uncommon with RTV-boosted Pis
Disadvantages:
Metabolic complications such as dyslipidemia, insulin resistance, and hepatotoxicity
GI adverse effects
CYP3A4 inhibitors and substrates: potential for drug interactions Adolescents
Ritonavir (Norvir™)
Ritonavir induces it own metabolism and it is one of the most potent CYP3A4 inhibitors known. “boosting.
This increases AUC, Cmax, Cmin and t1/2, thus the bioavailability of the boosted protease inhibitor is increased and improved penetration into HIV reservoirs may be achieved.
Fusion Inhibitors
Maraviroc (Selzentry™), Enfuvirtide (Fuzeon™)
Enfuvirtide (Fuzeon™)
Enfuvirtide (Fuzeon™)
Mechanism of Action
– 36 AA synthetic peptide, SC bid.
Inhibits entry of HIV into the CD4 cell
T-20 binds to glycoprotein gp41 (a protein on the viral membrane)
This binding prevents a change in the shape of the membrane protein and prevents fusion of the virus and the CD4 cell membrane
Maraviroc (Selzentry™)
Binds CCR5
Adverse effects/precautions:
Hepatotoxicity may be preceded by a systemic allergic reaction (pruritic rash, eosinophilia)
Dizziness/postural hypotension
Increased risk of CV events (MI, ischemic events)
Integrase Inhibitor
end with gravir
Mechanism of Action
Integrase Strand Transfer Inhibitor (INSTI)
Blocks catalytic activity of the HIV – encoded integrase preventing integration of viral DNA into the host chromosome
Potent activity against HIV-1 and 2
Active against HIV strains resistant to other antiretroviral agents
Integrase Inhibitor drugs
Raltegravir (RAL)
Elvitegravir (EVG)
Elvitegravir (EVG)
is an INSTI available as a fixed-dose combination product with cobicistat (COBI), tenofovir disoproxil fumarate (TDF,) and emtricitabine (FTC) (EVG/COBI/TDF/FTC), and is approved as a single-tablet, once-daily regimen for ART-naive patients.
EVG is metabolized primarily by CYP3A enzymes; as a result, CYP3A inducers or inhibitors may alter EVG concentrations.
COBI is a specific, potent CYP3A inhibitor with no activity against HIV. It acts as a PK enhancer of EVG, which allows for once daily dosing of the combination product
Elvitegravir side effects include
nausea and diarrhea,
upper respiratory tract infections and broncitis,
back and joint pain and
urinary tract infections
Keep in mind that this drug is only approved to be used with cobicistat a potent p4503A4 inhibitor.
