Chapter 10 Calculating Doses of Parenteral Medications

Parenteral Medications Given –intramuscularly –subcutaneously –intradermally –intravenously

Intramuscular (IM) Dosages Absorbed quickly Antibiotics, antihistamines, steroidal anti- inflammatory drugs, pain medications, immunizations Syringes calibrated in cubic centimeters (cc) or milliliters (mL)

3-cc Syringe Numbers on syringe are in ½-mL increments; start with ½ mL, end with 3 mL Each marking between numbers represents a tenth of one mL or 0.1 mL Figure 10-1.

3-cc Syringe 2.2 mL:

Typical Syringes 50-U insulin syringe (top) 3-cc syringe (middle) Tuberculin syringe (bottom) –when dose is less than 1 cc –calibrated to 0.01 mL Figure 10-2.

Parenteral Medications

Formula Method Ordered: meperidine (Demerol) 100 mg q3–4h IM for pain management Available: 50 mg/1 mL Are the units in the same measurement?

Formula Method Ordered: meperidine (Demerol) 100 mg q3–4h IM for pain management Available: 50 mg/1 mL Are the units in the same measurement? Yes

Formula Method Ordered: meperidine (Demerol) 100 mg q3–4h IM for pain management Available: 50 mg/1 mL Are the units in the same measurement? Yes 100 mg (DO) / 50 mg (DA) x 1 mL (Qty) = dose 100 mg / 50 mg x 1 mL = 2/1 x 1 mL = 2 mL What size syringe would you choose?

Formula Method Ordered: meperidine (Demerol) 100 mg q3–4h IM for pain management Available: 50 mg/1 mL Are the units in the same measurement? Yes 100 mg (DO) / 50 mg (DA) x 1 mL (Qty) = dose 100 mg / 50 mg x 1 mL = 2/1 x 1 mL = 2 mL What size syringe would you choose? 3cc

Formula Method with Reconstitution Ordered: methylprednisolone sodium succinate (Solu-Medrol) 125 mg IM qd for acute exacerbation of asthma Available: 500 mg vial of sterile white powder for injections Directions for reconstitution: Add 8 mL bacteriostatic water to vial and gently agitate until dissolved. Solution must be used within 48 hours. Dosage strength after reconstitution is 62.5 mg/mL. Are the units in the same measurement?

Formula Method with Reconstitution Ordered: methylprednisolone sodium succinate (Solu-Medrol) 125 mg IM qd for acute exacerbation of asthma Available: 500 mg vial of sterile white powder for injections Directions for reconstitution: Add 8 mL bacteriostatic water to vial and gently agitate until dissolved. Solution must be used within 48 hours. Dosage strength after reconstitution is 62.5 mg/mL. Are the units in the same measurement? Yes

Formula Method with Reconstitution 125 mg (DO) / 62.5 mg (DA) x 1 mL (Qty) = dose 125 mg / 62.5 mg x 1 mL = dose 2/1 x 1 mL = 2 mL What syringe would you choose?

Formula Method with Reconstitution 125 mg (DO) / 62.5 mg (DA) x 1 mL (Qty) = dose 125 mg / 62.5 mg x 1 mL = dose 2/1 x 1 mL = 2 mL What syringe would you choose? 3 cc

Proportional Method Ordered: meperidine (Demerol) 100 mg q3– 4h IM for pain management Available: 50 mg/1 mL Are the units in the same measurement?

Proportional Method Ordered: meperidine (Demerol) 100 mg q3– 4h IM for pain management Available: 50 mg/1 mL Are the units in the same measurement? Yes

Proportional Method 50 mg (DA) : 1 mL (dose form) = 100 mg (DO) : # mL (desired dose) 50 is to 1 as 100 is to x mL Answer: 2 mL What syringe would you choose?

Proportional Method 50 mg (DA) : 1 mL (dose form) = 100 mg (DO) : # mL (desired dose) 50 is to 1 as 100 is to x mL Answer: 2 mL What syringe would you choose? 3 cc

Proportional Method with Reconstitution Ordered: methylprednisolone sodium succinate (Solu- Medrol) 125 mg IM qd for acute exacerbation of asthma Available: 500 mg vial of sterile white powder for injections Directions for reconstitution: Add 8 mL bacteriostatic water to vial and gently agitate until dissolved. Solution must be used within 48 hours. Dosage strength after reconstitution is 62.5 mg/mL. Are the units in the same measurement?

Proportional Method with Reconstitution Ordered: methylprednisolone sodium succinate (Solu- Medrol) 125 mg IM qd for acute exacerbation of asthma Available: 500 mg vial of sterile white powder for injections Directions for reconstitution: Add 8 mL bacteriostatic water to vial and gently agitate until dissolved. Solution must be used within 48 hours. Dosage strength after reconstitution is 62.5 mg/mL. Are the units in the same measurement? Yes

Proportional Method with Reconstitution Ordered: methylprednisolone sodium succinate (Solu- Medrol) 125 mg IM qd for acute exacerbation of asthma Available: 500 mg vial of sterile white powder for injections Directions for reconstitution: Add 8 mL bacteriostatic water to vial and gently agitate until dissolved. Solution must be used within 48 hours. Dosage strength after reconstitution is 62.5 mg/mL. Are the units in the same measurement? Yes What is the desired dose?

Ordered: methylprednisolone sodium succinate (Solu- Medrol) 125 mg IM qd for acute exacerbation of asthma Available: 500 mg vial of sterile white powder for injections Directions for reconstitution: Add 8 mL bacteriostatic water to vial and gently agitate until dissolved. Solution must be used within 48 hours. Dosage strength after reconstitution is 62.5 mg/mL. Are the units in the same measurement? Yes What is the desired dose? 125 mg IM daily Proportional Method with Reconstitution

62.5 mg (DA) : 1 mL (dose form) = 125 mg (DO) : # mL (desired dose) 62.5 is to 1 as 125 is to x mL Answer: 2 mL What syringe would you choose?

Proportional Method with Reconstitution 62.5 mg (DA) : 1 mL (dose form) = 125 mg (DO) : # mL (desired dose) 62.5 is to 1 as 125 is to x mL Answer: 2 mL What syringe would you choose? 3 cc

Subcutaneous Doses Water-soluble solutions (analgesics, vitamin B 12, epinephrine, certain vaccines, insulin, heparin, anticoagulants) Volume typically 0.5–1.0 mL Maximum volume 2 mL May use 3mL, tuberculin or insulin syringe

Tuberculin Syringe 1 mL capacity Calibrated in hundredths of mL Figure 10-2.

Insulin Syringe Holds 1/2 mL (50 units) or 1 mL (100 units) Only use U-100 syringe for insulin administration Figure 10-3.

Do Not Massage Heparin, insulin, allergy injections Increases rate of absorption; may cause excessive bleeding in heparin injections

Calculating Units Ordered: penicillin G, 200,000 U IM Available: penicillin G, 250,000 U/mL Are the units in the same measurement?

Calculating Units Ordered: penicillin G, 200,000 U IM Available: penicillin G, 250,000 U/mL Are the units in the same measurement? Yes

Common CNS Stimulants Ordered: penicillin G, 200,000 U IM Available: penicillin G, 250,000 U/mL Are the units in the same measurement? Yes 200,000 U (DO) / 250,000 U (DA) x 1 mL = 0.8 mL What size syringe would you choose?

Calculating Units Ordered: penicillin G, 200,000 U IM Available: penicillin G, 250,000 U/mL Are the units in the same measurement? Yes 200,000 U (DO) / 250,000 U (DA) x 1 mL = 0.8 mL What size syringe would you choose? 1 cc tuberculin or 3 cc

Mixing Insulins Ordered: Humulin R 22 U and Humulin NPH 26 U Available: 10 mL vial of U-100 Humulin R and 10 mL vial of U-100 NPH Are the units in the same measurement?

Mixing Insulins Ordered: Humulin R 22 U and Humulin NPH 26 U Available: 10 mL vial of U-100 Humulin R and 10 mL vial of U-100 NPH Are the units in the same measurement? Yes

Mixing Insulins Ordered: Humulin R 22 U and Humulin NPH 26 U Available: 10 mL vial of U-100 Humulin R and 10 mL vial of U-100 NPH Are the units in the same measurement? Yes What is the desired dose?

Mixing Insulins Ordered: Humulin R 22 U and Humulin NPH 26 U Available: 10 mL vial of U-100 Humulin R and 10 mL vial of U-100 NPH Are the units in the same measurement? Yes What is the desired dose? Total amount of insulin is 48 U(22U + 26U = 48U)

Mixing Insulins What syringe would you choose?

Mixing Insulins What syringe would you choose? U-100 insulin syringe

Mixing Insulins What syringe would you choose? U-100 insulin syringe? How much insulin would you draw into this syringe?

Mixing Insulins What syringe would you choose? U-100 insulin syringe? How much insulin would you draw into this syringe? Total of 48 U (22 U of Humulin R and 26 U of Humulin NPH)

Mixing Insulins What syringe would you choose? U-100 insulin syringe? How much insulin would you draw into this syringe? Total of 48 U (22 U of Humulin R and 26 U of Humulin NPH) What route is used?

Mixing Insulins What syringe would you choose? U-100 insulin syringe? How much insulin would you draw into this syringe? Total of 48 U (22 U of Humulin R and 26 U of Humulin NPH) What route is used? Subcutaneous (sc)

Intradermal (ID) Dosages Administered into epidermal skin layer, above subcutaneous layer Volume administered—0.1 mL Always less than 0.2 mL Usually 1 mL tuberculin syringe Calibrated from 0.01 mL to 1 mL Injected in forearm, middle back

Review Type of syringe: Volume capacity: Calibration: Typically used for:

Review Type of syringe: –1 mL tuberculin Volume capacity: –1 mL Calibration: –0.01 mL Typically used for: –intradermal or subcutaneous

Review Type of syringe: Volume capacity: Calibration: Typically used for:

Review Type of syringe: –3 cc Volume capacity: –3 cc Calibration: –0.1 mL and 15 /mL Typically used for: –intramuscular or subcutaneous

Review Type of syringe: Volume capacity: Calibration: Typically used for:

Review Type of syringe: –U-100 Volume capacity: –100 units or 1 mL Calibration: –2 units Typically used for: –administration of insulin only