Drug administration supplies: syringes, pens, spacers and more
PTCB topic: Drug administration equipment and supplies
- U-100 insulin has 100 units per mL.
- A 0.3 mL syringe holds 30 units; 0.5 mL holds 50.
- Use a new pen needle for every injection, and never share a pen.
- Spacers fit metered-dose inhalers, not the ADVAIR DISKUS.
- Reconstitute a vaccine only with its own supplied diluent.
Key facts
- U-100 insulin has 100 units per mL: a 0.3 mL insulin syringe holds 30 units, 0.5 mL holds 50 units and 1 mL holds 100 units.
- LANTUS pen cartons do not include needles; a new pen needle is used for every injection, and a pen is never shared, even with a new needle.
- The HUMULIN R U-500 KwikPen shows actual U-500 units in its dose window, so no dose conversion is done and the insulin is never moved into a syringe.
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- A spacer or valved holding chamber is used with a metered-dose inhaler; the ADVAIR DISKUS label says not to use it with a spacer.
- A blunt fill filter needle draws drug from a glass ampule and is replaced before the injection.
- Vaccines are reconstituted only with the diluent supplied with them, never with stock sterile water or saline.
- For an adult IM vaccine, CDC lists a 1 mL or 3 mL syringe with a 22- to 25-gauge needle that is 1 to 1.5 inches long for most adults.
Quick check1 question · 2 more at the end
A patient's prescription calls for 35 units of U-100 insulin per injection, drawn from a vial. The pharmacy stocks U-100 insulin syringes in 0.3 mL, 0.5 mL and 1 mL sizes. What is the smallest syringe that holds the full 35-unit dose in a single injection?
Correct answer: B.
U-100 insulin contains 100 units in each mL, so a U-100 insulin syringe holds 100 units per mL of barrel: 0.3 mL holds 30 units, 0.5 mL holds 50 units and 1 mL holds 100 units. A 35-unit dose (0.35 mL) overfills a 0.3 mL syringe, so the 0.5 mL syringe is the smallest that fits. Insulin is measured with syringes marked in units, never with a syringe marked only in mL.
A A 0.3 mL U-100 syringe holds only 30 units, so 35 units would not fit in one draw.
B Correct: 35 units of U-100 insulin is 0.35 mL, and the 0.5 mL syringe (50 units) is the smallest size that holds it.
C A 1 mL syringe holds the dose, but it is not the smallest size that does, and smaller barrels are easier to read for small doses.
D A tuberculin syringe is marked in mL, not units; insulin syringes marked in units are used to measure insulin.
Full lesson
Each part starts with its main idea. Open a part when you want the details.
The short answer: Supplies must match the drug and its labeling. A U-100 insulin syringe holds 100 units per mL, so 0.3 mL holds 30 units and 0.5 mL holds 50. Insulin pens need a new pen needle for every injection and are never shared. Spacers fit metered-dose inhalers, ampules need a filter needle, and vaccines use only their own diluent.
1 Which syringe matches an insulin order?An insulin dose is measured in units, so it goes in a syringe marked in units. 1 min
An insulin dose is measured in units, so it goes in a syringe marked in units. Most insulin is U-100, meaning 100 units in each mL, and a U-100 insulin syringe holds 100 units per mL of barrel. A syringe marked only in mL, such as a tuberculin syringe, is never used for insulin.
| Insulin syringe | Holds (U-100) |
|---|---|
| 0.3 mL | 30 units |
| 0.5 mL | 50 units |
| 1 mL | 100 units |
Pick the smallest size that holds the whole dose. A 35-unit dose (0.35 mL) overfills a 0.3 mL syringe, so it needs the 0.5 mL size.
2 What do insulin pens and glucose supplies require?Pens need their own needles and their own patient, and supply math must count the priming units. 1 min
Pens need their own needles and their own patient, and supply math must count the priming units. The LANTUS labeling says needles are not included in the pen cartons and a new needle is used for each injection. A pen is never shared, even if the needle is changed.
- A LANTUS SoloStar pen holds 300 units and calls for a 2-unit safety test before every injection. At 22 units a day, each injection uses 24 units, so one pen gives 12 full doses.
- The HUMULIN R U-500 KwikPen's dose window shows actual units of U-500 insulin. No dose conversion is done, and the insulin is never moved from the pen into a syringe.
- FDA advises a control solution test when a new container of test strips is opened or the meter is dropped. Strip vials stay tightly closed, and meters are not shared.
3 Which inhaler gets a spacer, and what does a nebulizer need?Spacers belong to metered-dose inhalers, while nebulizer solutions need a nebulizer and compressor. 1 min
Spacers belong to metered-dose inhalers, while nebulizer solutions need a nebulizer and compressor. A spacer is a tube that fits an MDI's mouthpiece. A valved holding chamber adds a one-way valve, and with a face mask it lets young children use an MDI. The ADVAIR DISKUS, a dry powder inhaler, is labeled not to be used with a spacer.
Albuterol inhalation solution in 3 mL unit-dose vials goes into a jet nebulizer connected to an air compressor, used with a mouthpiece or face mask. The vials need no dilution and stay in their foil pouch until use.
4 What do filter needles, oral syringes and diluents do?Each of these supplies prevents a specific preparation error. 1 min
Each of these supplies prevents a specific preparation error. Match them like this:
| Supply | Job |
|---|---|
| Blunt fill filter needle | Draws drug from a glass ampule and keeps glass out; replaced before injecting |
| Oral syringe | Measures liquid doses by mouth with no needle; useful for children |
| Vaccine diluent | Reconstitutes one specific vaccine; not interchangeable |
FDA wants a liquid's dosing device marked in the same units as the directions, such as mL. CDC says to use only the diluent supplied with a vaccine, never a stock vial of sterile water or saline, and never to freeze diluents.
5 Which supplies go with an intramuscular vaccine?CDC sizes adult IM needles by sex and weight within a 22- to 25-gauge range. 1 min
CDC sizes adult IM needles by sex and weight within a 22- to 25-gauge range. Use a 1 mL or 3 mL syringe and a needle that is 1 to 1.5 inches long for most adults. A 5/8-inch needle is an option only under 60 kg (130 lb). Remember that a higher gauge number means a thinner needle.
6 What the technician doesThe technician makes sure every supply on the order fits the product and the patient. 1 min
The technician makes sure every supply on the order fits the product and the patient.
- Checks that the syringe, pen needle or device matches the product and the order.
- Adds needles, test strips, lancets or a spacer to the order when the prescriber orders them.
- Keeps each vaccine with its own diluent and sets out the needle size CDC lists.
- Sends questions about how to use a device to the pharmacist.
Common mistakes
The traps students fall into most. Read these before you practice.
Watch out: A higher gauge number means a thinner needle, not a thicker one.
Watch out: A pen's 2-unit safety test uses insulin from the pen, so it counts in supply math, not just the dose.
Watch out: Spacers go with metered-dose inhalers, not with dry powder inhalers like the Diskus.
Watch out: Stock sterile water is never a substitute diluent, even when the supplied diluent is sterile water.
Watch out: A tuberculin syringe is marked in mL, not units, so it is not an insulin syringe.
How to remember it
Think "units, unique, uses." Insulin goes in a syringe marked in units. Pens, meters and diluents are unique to one patient or one product. Each supply has one use: filter needles draw, spacers fit MDIs, nebulizers take solution.
Self-check:
- How many units does a 0.5 mL U-100 syringe hold?
- Why does a pen's safety test matter for supply math?
- Which inhaler type is labeled not for spacer use?
Show answers
- 50 units.
- U-100 means 100 units in each mL.
- 0.5 mL × 100 units/mL = 50 units.
- Each injection uses the dose plus the 2-unit safety test.
- A LANTUS SoloStar pen holds 300 units.
- At 22 units a day, each injection uses 22 + 2 = 24 units.
- 300 ÷ 24 = 12.5, so the pen gives 12 full doses.
- Without the test units, you would wrongly count 13 doses (300 ÷ 22 = 13.6).
- A dry powder inhaler, the ADVAIR DISKUS.
- Its label says not to use it with a spacer.
- Spacers belong to metered-dose inhalers.