Drug nutrient interaction Flashcards
What are the consequences of drug-nutrient interactions
- Loss of feeding access
- Loss of access for drug administration
- Inappropriate response to drugs and/or altered absorption of nutrients
ASPEN definition of D-N interaction
“an event that occurs when nutrient availability is altered by medication, or when a drug effect is altered, or an adverse reaction is caused by the intake of nutrients”
What are the types of D-N interaction
- Physical E.g., precipitation in PN formula, occluded EN tube
- Pharmaceutical E.g., Loss of drug activity/Toxicity
- Pharmacokinetic E.g.,E.g.,Loss of drug activity/Toxicity
- Pharmacodynamic E.g. Loss of drug activity/Toxicity
- Pharmacological E.g., Inability to provide PN or EN therapy because of adverse effects
What can u do to avoid D-N interaction in parenteral
- visual inspection
- avoid loss of drug activity due to mixing with incompatible mixture e. g., Octreotide acetate (treat diarrhea)
- Avoid mixing the drugs requiring high pH or low pH for solubility: PN usually has ph of 5-6.5, thus drugs requiring different pH for its solubility may not work as well
When drugs are administered with PN, either by admixture or co-infusion, the method of administration should ensure both the drug and PN formulation are stable and free from incompatibility.
Problem with thiamin
thiamin quickly loses its stability
thus you don’t want to rely on pre-mixed vitamins injections for someone who really needs thiamin-> separate IV for thiamin or PO administration of thiamin
Problems with salts? Solution?
salts easily precipitate
e. g. calcium salts
- calcium gluconate gluceptate, chloride
- calcium gluconate is the preferred form as it is known to be the least problematic
Problem with iron? Solution?
- e.g. iron cannot be added to ILE-> iron has to be added separately to, specifically, D5-AA solution in case of 2-in-1
- You cannot add iron to 3-in-1 due to its incompatibility with lipids
- Important for patients with high iron needs or who is receiving long-term parental nutrition-> may want to consider separate iron mix
What is the easiest solution for drug interaction with PN?
easiest way to avoid problems-> administer it separately
its the duration of the exposure that makes it difficult
co-infusion (separate infusion) where there is a short-period of time when solutions interact is usually well tolerated
Use Y-site infusion = less risk of interaction
What seems to be causing the problem when drugs are added to EN?
Presence of complete proteins
hydrolyzed formulas seem to be more compatible
Is adding drugs to EN problematic?
Approx.1/3 of the drugs in liquid dosage form evaluated for physical interactions with EN have demonstrated undesirable effects such as curdling, clumping, precipitation
What is a drug that is an exemption from the rule that drugs should not be mixed with EN?
insulin
WHAT can you do to avoid D-N interaction? Enteral/Parenteral
- If possible, administer drugs through different site (i.e., NOT vascular access device or feeding tube)
- If PO safe, best administration route is mouth.
- If drugs must be administered via same device as EN/PN formulation, stop feed and flush access device
- Before and after drug
- Between drug
- Usually normal saline used for VAD (amt specified by manufacturer)
- Water flush for an enteral tube. Minimum vol. 15ml
ASPEN suggestion about stopping EN when a drug has to be taken on an empty stomach
- ASPEN suggests that it is not necessary to hold a continuous EN feed for a drug that is to be taken on an empty stomach (some exceptions on last slide)
- For 1 hr before or 2 hours after drug administration (as is often done conventionally)-> this can add up to a lot of missed feed as some patients take a lot of drugs
- However, with a bolus or intermittent feeding schedule it is easier to accommodate drugs that should be taken on an empty stomach.
Formula-Related Factors of D-N interaction
- Nutrients that delay gastric emptying could delay drug absorption
- Fats, proteins, > 800 osmolality, large volume
- Calcium, Magnesium, and Iron can form complexes with drugs, resulting in poor absorption of drug.
* E.g., Tetracycline, ciprofloxacin
* some antibiotics will be bound by minerals in the feed
Drugs that are the main causes of D-N interaction aka the red flags
• Phenytoin (Dilantin)
• Carbamazepine (Tegretol)
- Dilantin and Tegretol are given to prevent seizures
• Fluoroquinolones (e.g., Cipro)
• Warfarin (Coumadin)
