Preparing Sterile Admixture

outside the gut. anything that bypasses the GI tract: IV, IM, SC, ID, plus epidural/intrathecal/intra-articular, etc.

parenteral

into a vein

angles/technique: typically ~25° entry relative to skin.

use cases: rapid onset, continuous infusions, titratables (pressors, insulin, heparin), large volumes (hydration, TPN).

forms: solutions only (no suspensions); LVPs (250-1000 mL), SVPs (25-250 mL).

intravenous

short-term, osmolarity generally ≤900 mOsm/L and near-physiologic pH; irritants/vesicants can damage veins.

peripheral IV

allows hypertonic solutions, TPN, vesicants (chemo), long-term therapy.

central line

into muscle.

angle: 90° straight in.

volume (adult): deltoid ≤1 mL, ventrogluteal/vastus lateralis 2-5 mL (check drug-specific limits).

onset: 10-30 min (faster than SC, slower than IV).

examples: vaccines, haloperidol decanoate, penicillin G benzathine.

cautions: anticoagulated pts (hematoma), poor perfusion states (unreliable absorption).

big volumes or oily/viscous formulations → not SC.

intramuscular

into subcutaneous fat.

angle: 45° traditionally; 90° with short pen needles/adequate tissue.

volume: ≤1 mL typical (many biologics allow 1.5-2 mL but check PI).

onset: slower than IM; sustained absorption.

examples: insulin, GLP-1 RAs, heparin/enoxaparin, many monoclonal antibodies.

pearls: rotate sites; avoid rubbing after heparin; watch osmolarity/pH (tissue irritation).

subcutaneous

into the dermis.

angle: 10-15°, bevel up, make a wheal.

volume: 0.1 mL max.

examples: TB (Mantoux), allergy testing.

intradermal

short cannula in arm/hand. for short-term, non-vesicant, near-physiologic stuff.

peripheral

longer than PIV, not central; still limited compared with central for vesicants/osmolarity.

midline

catheter tip in SVC; good for TPN, chemo, hypertonic/irritants, long duration.

central

ready-to-withdraw solution. multi-dose have preservatives; single-dose usually don't.

vials

must reconstitute with a sterile diluent (e.g., NS, SWFI, BWFI—but choose what the PI says). calculate final concentration.

powder vial

contains benzyl alcohol → not for neonates and never for intrathecal/epidural.

bacteriostatic water for injection

outer vial isn't _____________; the stopper must be scrubbed with 70% IPA and allowed to dry before piercing.

sterile

single-use glass you snap open. always use a filter (filter needle or filter straw, typically 5 micron) to withdraw to avoid glass shards.

ampule

0.9% NaCl (NS), D5W, LR, etc. pick the diluent based on compatibility and the PI: some drugs are NS-only (e.g., phenytoin), some D5W-only (e.g., amphotericin B conventional), some either.

IV solutions (base fluids)

no preservatives; often first step, then further dilute with NS/D5W.

sterile water for injection

not for intrathecal/neonates; volume per day limit exists for adults; follow PI.

benzoyl alcohol preserved (BWFI)

IM __________________ into muscle.

90°

SC _____________ (or 90° with short pens).

45°

IV __________________ to enter vein.

~25°

ID _______________ just under epidermis → wheal.

10-15°

select all that apply:

how do we put a sterile admixture together?

1. identify drug form

2. use correct diluent

3. use correct base solution

4. aseptic steps

5. label

instant bioavailability (no absorption step) and no practical volume cap—it's patient/clinical-status dependent.

intravenous

select all that apply:

how are intravenous solutions delivered?

1. IV push (IVP/bolus)

2. IVPB (intermittent)

3. continuous infusion

small volume over minutes.

IV push (IVP/bolus)

25-250 mL over a set time.

IVPB (intermittent/secondary)

hours-days at a fixed rate.

continuous infusion

select all that apply:

which of the following is correct about the IV route of administration?

1. fastest onset

2. titratable

3. best for irritants

4. no set max volume

5. aqueous solutions

select all that apply:

which of the following are correct about intramuscular injections?

1. reliable absorption

2. slower than IV

3. more painful than IV

4. volume up to ~5 mL

5. aqueous or oil/suspensions

6. rotate sites

select all that apply:

which of the following are correct about intradermal injections?

1. stings

2. strictly diagnostics

3. 0.1 mL

4. 10-15° angle

5. make a wheal

select all that apply:

which of the following is true about subcutaneous injections?

1. slow, sustained absorption

2. ≤ 1 mL typical

3. rotate sites

4. avoid rubbing after heparin/enoxaparin

into the space outside the dura. diffuses to nerve roots.

epidural

directly into CSF (subarachnoid space). stronger/rapid CNS effect.

intrathecal

labor analgesia, post-op pain, localized nerve blocks.

epidural

severe pain pumps, spinal anesthesia, some chemo.

intrathecal

select all that apply:

which of the following do epidural and intrathecal administration have in common?

1. preservative-free components

2. low endotoxin/particulate tolerance

3. catastrophic risk if violated

never for neuraxial or neonates.

BWFI (benzyl alcohol)

any device that lets you deliver meds/fluids into the venous system.

vascular access

typically pH < 5 or > 9 or osmolarity > ~600 mOsm/L. can burn/ache along the vein but usually won't necrose tissue if it stays intravascular.

irritants

causes blistering/tissue necrosis if it leaks into tissue.

vesicant

the more extreme the pH/osmolarity, the more you should be side-eyeing ____________ lines.

peripheral cannula

if it burns/irritates or is hypertonic, _______________ access lets the blood flow "hide" the harshness by diluting it immediately.

central venous access

quick access for standard fluids/antibiotics compatible with its criteria.

peripheral cannula

longer therapy; still NOT central—don't use for TPN/vesicants.

midline catheter

long-term, high-osmolarity, vesicants, multiple infusions, frequent labs.

central venous access

select all that apply:

when will we use a central venous access device?

1. no good peripheral access

2. vesicant meds

3. TPN

4. hypertonic solutions

5. hemodynamic monitoring

6. dialysis/hemofiltration

7. plasma exchange

8. transvenous pacing

9. frequent blood draws

central venous access advantages:

multiple lumens → run _____________ drugs simultaneously

fewer sticks; reliable access; fast dilution in SVC

incompatible

inserted directly into internal jugular vein, subclavian, or femoral vein; tip in SVC. short-term, higher infection risk (esp. femoral), easy to place at bedside. can have many lumens (up to 5).

non-tunneled catheters

catheter tunnels 10-15 cm under skin before entering vein; cuff fibrosis anchors it. long-term therapies (oncology, TPN). lower infection than non-tunneled.

tunneled catheters

inserted in upper arm (basilic/cephalic), tip ends in SVC → it is a central line. weeks to months; outpatient antibiotics, TPN, chemo. multiple lumens possible.

peripherally inserted central catheters

surgically implanted under skin; catheter to SVC; accessed with non-coring Huber needle through a self-sealing septum. lowest maintenance between uses; ideal for intermittent long-term therapy (chemo).

implantable port (totally implantable venous access device)

select all that apply:

how do we access a port?

1. palpate the port

2. prep skin

3. use Huber needle

4. pierce the septum at 90°

5. confirm blood return

6. flush per protocol

7. connect infusion

deliver continuous, intermittent (IVPB), and bolus doses at precise rates/volumes. use a drug library (build by pharmacy) with unit-specific limits for adults, peds, NICU, etc.

smart infusion pumps

select all that apply:

what are some safety features on smart infusion pumps?

1. soft stops

2. hard stops

3. barcoding/EMR integration

drug is dry to extend shelf life or because liquid would be unstable. reconstitute with the right diluent (SWFI/NS/BWFI per PI), calculate the final concentration, then further dilute if needed.

powder vials

ready-to-withdraw solutions; may still require dilution. often larger vials (electrolytes, some narcotics). multi-dose vials have preservatives; single-dose usually don't.

liquid vials

the outside of the vial isn't sterile; scrub stopper with _____________ and let it dry before piercing. multi-dose ≠ forever: respect beyond-use dating policies once entered.

70% IPA

single-dose glass containers (often

ampules

(for reconstitution/volume makeup):

SWFI (no preservatives), BWFI (benzyl alcohol), NS (0.9% NaCl), D5W.

choose exactly what the PI or stability guide states.

diluents

(carriers): LVPs (250-1000 mL) and SVPs (25-250 mL). used for hydration and to deliver drugs at safe concentrations/rates.

IV solutions

select all that apply:

what is the bench-level workflow?

1. identify form

2. pick the correct diluent

3. choose the final bag

4. confirm line type

5. label

>100 mL (commonly 250, 500, 1000 mL). Think hydration, TPN, continuous drips, or big dilutions for irritants.

large volume parenteral (LVP)

≤100 mL (25, 50, 100 mL). think IVPB antibiotics, intermittent meds.

small volume parenteral (SVP)

solvent / carrier with no therapeutic effect (ideally no toxicity). must meet USP sterility, pyrogen, and endotoxin standards. your choice affects compatibility, tonicity, pH, and therefore line selection (peripheral vs central).

vehicle

most common reconstitution diluent. no preservatives.

water for injection

0.9% NaCl (NS), D5W, LR. used as final carriers in LVP/SVP.

aqueous isotonic vehicles

propylene glycol, PEG 300/400, ethanol (in specific products like lorazepam, phenytoin). increase solubility but can irritate → often need central access and slow rates.

water-miscible solvents

oils (cottonseed, sesame) used for IM depot products, not IV.

non-aqueous vehicles

sterile, apyrogenic, no preservative. use for reconstitution, then usually further dilute with NS/D5W.

sterile water for injection

sterile with a preservative (often benzyl alcohol). never for neonates. never for intrathecal/epidural. generally avoid for large-volume parenterals (meant for small repeated withdrawals).

bacteriostatic water

may be prepared with water in certain protocols, but clinically prefer isotonic carriers to avoid hemolysis.

sodium bicarbonate drips

effective concentration of particles that drive water movement across cell membranes. dictates peripheral vs central. large deviations irritate endothelium → pain, phlebitis, extravasation risk.

tonicity

NS, D5W after metabolism is hypotonic in effect but as a bag it's ~252 mOsm/L (borderline). cells don't swell/shrink.

isotonic solution

pulls water out of cells → cell shrink.

examples: 3% saline, concentrated dextrose, many drug admixtures at high concentration. prefer central line.

hypertonic solution

water into cells → swell.

examples: 0.45% NS, sterile water (never as IV carrier by itself). fluids can hemolyze RBCs peripherally—use judiciously.

hypotonic solution

isotonic window: ~280-310 mOsm/L (close to plasma). gentle on veins → okay for peripheral lines when pH is reasonable.

usual suspects: 0.9% sodium chloride (NS), bacteriostatic NS (has preservative; not for neonates or neuraxial), Ringer's / Lactated Ringer's (LR), dextrose 5% (D5W)

how to choose among them: start with what the PI/Trissel's says. some drugs are NS-only (e.g., phenytoin), some D5W-only (e.g., amphotericin B deoxycholate), some either.

aqueous isotonic vehicles

used when a drug won't dissolve in plain water. they mix with water but add solvency.

examples: ethyl alcohol (ethanol), propylene glycol (PG), polyethylene glycol (PEG).

these formulations can be irritating, osmolarity can be high, and some solvents (esp. PG) stack up at high doses → hypotension, metabolic acidosis, renal issues.

often slow rates, sometimes filters, and frequently central line when concentrated.

water-miscible solvents

for drugs that only live their best life in oil, or in parenteral nutrition lipid emulsions.

forms: emulsified oils (soybean/safflower) → part of TPN lipids; can be given peripherally or centrally depending on total TPN osmolarity.

fixed oils (peanut, cottonseed, corn, sesame) → IM depot injections (e.g., medroxyprogesterone, haloperidol decanoate).

rules: never IV as straight oil solutions; that's emboli city. check allergy history (peanut/soy) when relevant.

non-aqueous vehicles

select all that apply:

how do we choose the appropriate vehicle?

1. the label/PI

2. compatibility check

3. patient factors

4. electrolyte problems

5. allergies

6. tonicity/pH/vesicant status

7. labeling & rate