Dosing and Administration

Part of Antibiotics

Practical methods for administering penicillin preparations — oral, intramuscular, and topical routes — with procedural details for each.

Why This Matters

Having a penicillin preparation is only part of the challenge. Getting the drug into the patient in the right amount, by the right route, at the right intervals, determines whether treatment succeeds or fails. Poor administration technique can render effective antibiotics useless or even introduce new infections.

This article covers the practical procedural side of administration — how to prepare doses, which route to use for which situation, and how to perform intramuscular injection safely without modern medical equipment. These are skills that should be practiced and taught before urgent need arises.

Choosing the Administration Route

Route	Best For	Advantages	Disadvantages
Oral	Mild-moderate infections, cooperative patients	No skill required, safer	Variable absorption, stomach acid degrades some penicillins
Intramuscular	Severe infections, vomiting patients	Reliable absorption, faster	Requires skill, painful, infection risk at site
Topical	Wound surface infections only	Direct delivery, lower systemic dose	Does not reach deep tissue or blood
Intravenous	Critical sepsis	Fastest action	Extremely high infection risk without sterile conditions; generally avoid

General rule: Start with oral if the patient can tolerate it. Switch to IM if oral fails or infection is severe. Avoid IV entirely without reliable sterile IV setup.

Oral Administration

Preparation

Crude penicillin preparations for oral use:

1. Measure dose into a clean cup — volume based on your concentration assessment (see Dosage Guidelines)
2. Check for visible contamination — the preparation should be yellowish-clear or pale golden; cloudiness or unusual color suggests contamination, discard
3. Administer at room temperature — cold preparations are harder to tolerate; warm to body temperature (not above 37°C) if needed

Administration

• Have patient sit upright or stand
• Administer on an empty stomach when possible (1 hour before meals or 2 hours after)
• If stomach is empty and patient experiences nausea, allow a small amount of bland food (bread, rice) before dose
• Ensure patient swallows the entire dose — follow with water

Monitoring

After oral administration:

• If patient vomits within 30 minutes of dose, repeat the dose
• If patient vomits within 30–60 minutes, partial absorption occurred — give half dose more
• If patient cannot retain any oral fluid, switch to IM route

Intramuscular Injection

Intramuscular injection is a skill with a learning curve but is achievable without formal medical training. The stakes are high — improper technique risks introducing infection, hitting a nerve, or injecting into a blood vessel.

Equipment Needed

• Sterile syringe and needle (18–21 gauge for viscous preparations; 23–25 gauge for aqueous solutions)
• Alcohol pad or cloth soaked in 70% alcohol
• Clean, well-lit workspace
• Assistant to stabilize patient if possible

Injection Sites

Preferred sites in order:

1. Ventrogluteal site (safest): Outer side of hip. Patient lies on side. Landmark: place heel of your hand on greater trochanter (hip bone prominence), fingers toward navel. The injection site is in the center of the triangle formed by your index and middle fingers.

2. Vastus lateralis (thigh): Outer middle third of thigh, patient lying or sitting. Grasp muscle mass firmly. Good for infants and unconscious patients.

3. Dorsogluteal (buttock): Divide the buttock into four quadrants; inject in the upper outer quadrant. Avoid the lower quadrants where the sciatic nerve runs.

Never inject into:

• Inner arm or inner thigh
• Directly over bone
• Into areas of existing infection or bruising
• The same site as the previous injection

Procedure

1. Wash hands thoroughly with soap and water
2. Prepare the injection: draw the penicillin preparation into the syringe, expel air bubbles
3. Clean the site: wipe injection site firmly with alcohol-soaked cloth in expanding circles; allow to dry 30 seconds
4. Position the patient: appropriate position for chosen site; patient should be relaxed, muscles not tensed
5. Stretch the skin at injection site (do not bunch/pinch for IM; that is for subcutaneous)
6. Insert the needle at 90 degrees to the skin, quick confident motion, full length of needle
7. Aspirate: pull plunger back 5–10 seconds; if blood enters syringe, withdraw needle, discard, re-prepare with new syringe
8. Inject slowly: push plunger steadily over 5–10 seconds for 5 mL; slow injection reduces pain and muscle damage
9. Withdraw smoothly: pull needle straight out; apply pressure with clean cloth immediately
10. Do not recap needle by bringing cap to needle — set cap on surface and slide needle into it one-handed, or dispose safely

Post-Injection Care

• Apply pressure to injection site for 2–3 minutes if bleeding
• Mild local pain and soreness is normal for 24–48 hours
• Warm compress to site after 2 hours reduces pain and improves absorption
• Note the injection site in your records; rotate sites for subsequent doses

Signs of Injection Complications

• Nerve hit: immediate sharp electrical pain radiating down limb — withdraw needle immediately, choose different site
• Intravascular injection: blood in syringe on aspiration — withdraw, discard, re-prepare
• Infection at site: increasing pain, redness, warmth, swelling at injection site 24–48+ hours after — treat as wound infection

Topical Administration

For surface wound infections:

1. Clean wound thoroughly with saline or clean water before applying penicillin preparation
2. Soak a clean cloth or dressing in concentrated penicillin extract
3. Apply directly to wound surface; cover with a secondary dry dressing
4. Change every 8–12 hours
5. Do not rely on topical alone for deep or spreading infections — systemic administration is required

Topical application is most useful for:

• Superficial burns with early bacterial colonization
• Infected skin ulcers
• Suspected infected suture lines
• As adjunct to systemic treatment in severe wound infections

Administration to Special Populations

Children

• Calculate weight-based dose carefully
• Oral administration preferred when possible
• For IM in children, vastus lateralis (thigh) is preferred — more muscle mass available, easier to control
• Use smallest effective needle; distract the child; quick confident injection with pre-warmed preparation

Unconscious Patients

• Oral route is absolutely contraindicated — aspiration risk
• IM route only, using ventrogluteal or vastus lateralis sites
• Turn patient after injection to prevent pressure on injection site

Pregnant Women

• Penicillin-class antibiotics are among the safest for pregnancy at all stages
• Do not withhold treatment for serious infection due to pregnancy
• Avoid IM injection into abdomen — use thigh or hip sites
• Monitor for premature contractions if patient is near term

Recordkeeping

For every dose administered:

• Date and time
• Drug preparation used (batch ID if tracked)
• Volume and estimated dose
• Route and site
• Patient response (temperature, pain level, wound appearance)

This record is essential for determining whether treatment is working, when to escalate, and for future reference in treating similar infections. In a community setting, these records become the foundation of medical knowledge for subsequent generations.