Insulin Types and Administration: A PTCB Study Guide

Understanding Insulin Categories

Insulin is one of the most commonly dispensed medications in pharmacy. Knowing the different types, their onset and duration of action, brand names, and storage requirements is essential for both the PTCE and daily practice. Errors involving insulin are among the most common and dangerous medication mistakes.

Rapid-Acting Insulin

Onset: 10-15 minutes. Peak: 1-2 hours. Duration: 3-5 hours.

• Lispro (Humalog)
• Aspart (NovoLog)
• Glulisine (Apidra)

Given immediately before or after meals to cover postprandial blood sugar spikes.

Short-Acting Insulin

Onset: 30-60 minutes. Peak: 2-4 hours. Duration: 5-8 hours.

• Regular insulin (Humulin R, Novolin R)

Can be given IV in hospital settings. The only insulin type that can be administered intravenously.

Intermediate-Acting Insulin

Onset: 1-2 hours. Peak: 4-12 hours. Duration: 12-18 hours.

• NPH insulin (Humulin N, Novolin N)

Cloudy in appearance. Must be gently mixed before injection. Often combined with rapid-acting insulin.

Long-Acting Insulin

Onset: 1-2 hours. Minimal or no peak. Duration: 20-24+ hours.

• Glargine (Lantus, Basaglar, Toujeo)
• Detemir (Levemir)
• Degludec (Tresiba) - ultra-long acting, duration up to 42 hours

Provides basal insulin coverage. Clear in appearance. Cannot be mixed with other insulins in the same syringe.

Storage Requirements

Unopened insulin should be refrigerated at 36-46 degrees F (2-8 degrees C). Once opened (in-use), most insulin pens and vials can be stored at room temperature for 28 days (varies by product). Never freeze insulin. Inspect for particles, discoloration, or clumping before dispensing.

Insulin questions are high-yield for the PTCE. Use PTCB flashcards to memorize onset, peak, and duration for each type.