💉 Parenteral Medications

📌 Definition

• Parenteral medications are injected directly into the body by various routes.
• They may be packaged in ampules, vials, prefilled cartridges, or syringes.

📚 Background

• Used when the GI tract cannot be used.
• Commonly for: insulin, opioid analgesics, vaccines, antibiotics.

🔹 Routes of Administration

• Subcutaneous (SC) → beneath the skin.
• Intramuscular (IM) → into the muscle.
• Intravenous (IV) → into the vein.
• Intrathecal → into the spinal canal/CSF.

✅ Pros

• Rapid medication delivery
• Calorie supplementation

⚠️ Cons

• Adverse metabolic reactions
• Potential for infection

👉 Mnemonic to remember the four main routes:

“S.I.I.I” → Subcutaneous, Intramuscular, Intravenous, Intrathecal

💉 Injection Angles & Techniques

💉 Parenteral Medications – Containers

🧪 Ampule

• Glass container with a narrow neck that snaps open.
• Always single dose.
• Steps:
1. Tap ampule to move liquid to bottom.
2. Snap neck open with gauze/alcohol swab.
3. Use a filter needle to aspirate (prevents glass shards).
4. Replace filter needle with sterile needle before injection.

💉 Vial

• Glass or plastic container sealed with a rubber membrane, covered by a protective lid.
• Types:
• Single-dose vials → contain one dose (reduce error risk).
• Multidose vials → contain multiple doses (aseptic technique required).
• May contain liquid or powder (powder requires reconstitution).
• Steps:
1. Remove cap, clean stopper with alcohol.
2. Inject air equal to volume needed.
3. Invert vial and withdraw medication.
4. Remove air bubbles before injection.
• Reconstitution (if powdered):
1. Withdraw diluent into syringe.
2. Inject into vial and gently roll to dissolve.
3. Label with date, time, and initials after mixing.

🖊️ Prefilled Cartridge / Syringe

• Ready-to-use, single-dose (e.g., enoxaparin, morphine, insulin pens).
• Advantages: sterile, convenient, reduces dosing errors.
• Some prefilled syringes (like enoxaparin) include an air bubble that should NOT be expelled (prevents leakage and ensures full dose).

📊 Comparison Table

Professor Note:

Haloperidol lactate is a short-acting, water-based injection used for quick control of agitation or psychosis. Haloperidol decanoate is an oil-based, long-acting depot injection that works slowly and lasts weeks for maintenance treatment.

You should not confuse them because if you give decanoate instead of lactate, the patient won’t get rapid relief in an emergency; and if you give lactate instead of decanoate, the patient won’t have long-term control and may relapse.

💉 Parenteral Medications – Normal Injection Dosages

💪 Intramuscular (IM)

• 👶 Infant: 1 mL
• 🧒 Child: 2 mL
• 🧑 Adult: 3 mL (in deltoid 2 mL)

🩹 Subcutaneous (SC)

• 👶 Infant: 0.1 mL
• 🧒 Child: 0.5 mL
• 🧑 Adult: 1 mL

📘 Intradermal (ID)

• All ages: no more than 0.1 mL

📕Question:

■ The prescriber ordered Haloperidol 3 mg IM q4h prn.

What are we missing? -> Reason for medication.

💊 Parenteral Medication in Powder Form

📌 Key Points

• Some medications come in powdered form and must be mixed with a diluent/solvent before use.
• Common diluents:
• Sterile water
• 0.9% Sodium Chloride (Normal Saline)
• Always check the medication label or package insert for:
• Correct type of diluent
• Correct volume to use
• Verify the ordered route (IM or IV) before reconstitution → different routes may require different concentrations.

🧾 Steps for Reconstitution

1. Add diluent → Combine liquid diluent with powdered medication.
2. Transfer & mix → Gently roll or swirl vial to dissolve powder (do not shake vigorously unless instructed).
3. Draw up solution → Use sterile syringe to withdraw the mixed solution.
4. Administer → Give via the ordered route (IM or IV).

💊 Reconstitution – Key Idea

• When you add diluent to powder, the drug dose (mg) stays the same.
• What changes is the volume and concentration.
• More diluent → less concentrated solution.
• Less diluent → more concentrated solution.
• If the solution is too concentrated, it can irritate the injection site.

Divide 250,000 / 500,000 /100,000/ by 200,000 unit you get 0,8 0.4 and 0.2.

🩸 Heparin – Anticoagulant

📌 Key Facts

• Action: Inhibits clot formation by enhancing antithrombin III, which blocks Factor Xa and Thrombin.
• Use: Prevents conversion of fibrinogen → fibrin.

💉 Routes

• ✅ Subcutaneous (SC)
• ✅ Intravenous (IV)
• ❌ Never intramuscular (IM) → risk of hematomas.

⚠️ Safety Notes

• High-alert drug → dosing errors can be dangerous.
• Supplied and ordered in units (not mg).
• Available in single-dose and multi-dose vials.
• Commercial preparations also exist.

🚨 Adverse Effects

• Bleeding
• Thrombocytopenia (low platelets, risk of HIT – heparin-induced thrombocytopenia)
• Drug–drug interactions

👉 Simple memory hook:

“Heparin → H” = Hematoma risk IM, High alert, HIT risk.

🩸 Heparin Administration Routes

🩹 Subcutaneous (SQ)

Purpose: Prevention of clots (DVT, PE, post-surgery)

Key Points:

• Usually given in the abdomen
• Fixed doses (e.g., 5,000 units q8–12h)
• No continuous monitoring required for prophylactic doses

💉 Intravenous (IV) Bolus

Purpose: Immediate anticoagulation

Key Points:

• Rapid onset
• Often given before starting a continuous drip
• Dosing is weight-based

💧 Intravenous (IV) Infusion / “Drip”

Purpose: Treatment of active clots (DVT, PE, atrial fibrillation)

Key Points:

• Continuous infusion allows precise control of anticoagulation
• Monitored with aPTT to keep blood in therapeutic range
• Infusion rate is adjusted based on lab results for safety

👉 Quick memory hook:

• SQ = “Set dose, no monitoring” (prevention)
• IV Bolus = “Boom! Rapid action” (emergency)
• IV Drip = “Steady & controlled” (treatment + monitoring)

💉 Dosage Calculation – Heparin Example

Order: Heparin 3,500 units SC q12h

Available: 5,000 units / 1 mL

🧾 Step Method

1️⃣ Write the formula:

Volume to give (mL)=Desired dose (units)Available dose (units/mL)\text{Volume to give (mL)} = \frac{\text{Desired dose (units)}}{\text{Available dose (units/mL)}}

Volume to give (mL)=Available dose (units/mL)Desired dose (units)

2️⃣ Plug in the numbers:

3,5005,000=0.7 mL\frac{3,500}{5,000} = 0.7 \, \text{mL}

5,0003,500=0.7mL

3️⃣ Final Answer:

➡️ 0.7 mL to administer

✅ Simple Rule:

Always Desired ÷ Available × Volume