Fertility Topics Explained from the Experts at SFS
Intralipid (IL) is a solution of small lipid droplets suspended in water. When administered intravenously, IL provides essential fatty acids, linoleic acid (LA), an omega-6 fatty acid, alpha-linolenic acid (ALA), an omega-3 fatty acid. It is made up of 20% soybean oil/fatty acids (comprising linoleic acid, oleic acid, palmitic acid, linolenic acid and stearic acid), 1.2% egg yolk phospholipids (1.2%), glycerin (2.25%) and water (76.5%). Possible Mode of Action: It is thought that fatty acids within the emulsion serve as ligands to activate peroxisome proliferator-activated receptors (PPARs) expressed by the NK cells. This is believed to decrease NK cytotoxic activity, and thereby enhance implantation. A growing number of IVF programs, including ours, perform egg retrieval under conscious sedation using Propofol, a short acting hypnotic agent. Interestingly, similar to Intralipid 1% Propofol also contains the same concentration of soybean oil, and purified egg phospholipid, with glycerin. Perhaps its use offers a fringe benefit in cases of immunologic implantation dysfunction. Whatever the exact mechanism of action might be, IL exerts a modulating effect on certain immune cellular mechanisms largely by down-regulating cytotoxic /activated natural killer cells (NKa). This effect is enhanced through the concomitant administration of corticosteroids such as dexamethasone, prednisolone and prednisone which in my opinion do so by immune modulation of T cells . The combined effect of IL + steroid therapy is thought to suppresses pro-inflammatory cellular (Type-1) cytokines such as interferon gamma and TNF-alpha, produced in excess by activated NK cells and cytotoxic T cells. IL will in about 80% of cases, successfully down-regulats activated natural killer cells (NKa) within 2-3 weeks. In this regard it is likely to be just as effective as IVIg but at a fraction of the cost and with a far lower incidence of side-effects. Its effect lasts for 4-9 weeks when administered in early pregnancy. Can in-vitro (laboratory) tests assess for an immediate benefit of IL on Nka? Since the down-regulation of NKa through IL (or IVIg) therapy can take several weeks to become detectable, it follows that there is really no benefit in trying to assess the potential efficacy of such treatment by retesting NKa in the laboratory after adding IL (or IVIg) to the cells being tested. Treatment of NKa Using IL:
Contra-Indications and Cautions with Intralipid Infusion: IL is only contraindicated in conditions associated with severely disordered fat metabolism (e.g. severe liver damage, acute myocardial infarction and shock, Rarely, hypersensitivity has been observed in patients allergic to soybean protein, egg yolk and egg whites and where fat metabolism may be disturbed (e.g. renal insufficiency, uncontrolled diabetes, certain metabolic disorders and in cases oif severe infection (sepsis) sepsis Adverse Reactions During Infusions of IL (rare): Adverse reactions (rare) reported to occur during and/or following infusion of Intralipid include: transient fever, chills, nausea, vomiting, headache, back or chest pain with dyspnea and cyanosis. In cases of verified or suspected liver insufficiency, liver function must be closely followed. If increased levels of transaminases, alkaline phosphatases or bilirubin appear, infusion of Intralipid should be withheld or postponed, until normalization is achieved. Very rare cases of hypersensitivity have been observed in patients allergic to soybean protein, egg yolk and egg whites. Fat metabolism may be disturbed in conditions such as renal insufficiency, uncompensated diabetes, certain forms of liver insufficiency, metabolic disorders and sepsis. Administration: The drip rate is adjusted to 500 ml of a 20% solution should be infused over about 2-3 hours. The infusion should be started at half the infusion rate during the first 30 minutes, under supervision.
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