How is Human Mixtard (insulin) administered and what is the typical dosage?

Human Mixtard: Administration and Dosage Guidelines

What is Human Mixtard?

Human Mixtard is a premixed biphasic insulin containing 30% soluble (rapid-acting) insulin and 70% NPH (intermediate-acting) insulin, administered subcutaneously typically twice daily before meals. 1, 2

Administration Technique

Injection Sites and Rotation

• Inject into subcutaneous tissue of the upper arm, anterior and lateral thigh, buttocks, or abdomen (excluding a 2-inch radius around the navel) 1
• Rotate injections systematically within one anatomical area (e.g., different sites within the abdomen) rather than rotating between different body regions with each injection to minimize day-to-day absorption variability 1
• The abdomen has the fastest absorption rate, followed by arms, thighs, and buttocks 1

Injection Procedure

• Roll the vial or pen gently between palms before each injection to resuspend the insulin—Mixtard should appear uniformly cloudy, not clear 1
• Most individuals should lightly grasp a skin fold, release the pinch, then inject at a 90° angle 1
• Thin individuals or children may need to pinch skin and inject at a 45° angle using short needles to avoid intramuscular injection, especially in the thigh 1
• Keep the needle embedded in skin for 5 seconds after complete insulin delivery, particularly with pen devices 1

Typical Dosing Regimen

Standard Twice-Daily Schedule

• Administer Mixtard twice daily: before breakfast and before the evening meal 1, 3
• The timing should be consistent, with injections given 0-15 minutes before meals 4

Initial Dosing

• For insulin-naïve type 2 diabetes patients inadequately controlled on oral medications, start with 10 units once or twice daily, then titrate to achieve glycemic targets 5
• Alternatively, use 0.1-0.2 units/kg/day as the starting dose 5
• For type 1 diabetes, total daily insulin requirements typically range from 0.4-1.0 units/kg/day, with 0.5 units/kg/day being typical for metabolically stable patients 6

Dose Distribution

• In the Romanian Young Diabetics Study, patients aged 6-18 years received a mean total daily dose of 32.6-33.9 IU split between two injections 3
• The specific distribution between morning and evening doses should be adjusted based on blood glucose monitoring results 1, 3

Dose Titration and Adjustment

Monitoring Requirements

• Perform self-monitoring of blood glucose (SMBG) on a prescribed schedule to guide dose adjustments 1, 7
• Adjust doses based on fasting and pre-meal blood glucose values, with the goal of achieving target ranges without hypoglycemia 1, 4
• Measure HbA1c every 3 months during dose optimization 3

Titration Principles

• Increase doses by 2-4 units every 3 days until fasting blood glucose reaches 80-130 mg/dL (4.4-7.2 mmol/L) 6
• If hypoglycemia occurs without clear cause, reduce the dose by 10-20% immediately 8, 6
• Variables affecting insulin action include dose, injection site, blood flow, temperature, and physical activity level 1

Storage and Handling

Storage Guidelines

• Refrigerate unopened vials at 36-46°F (2-8°C) 1
• Avoid extreme temperatures (<36°F or >86°F, <2°C or >30°C) and excess agitation to prevent loss of potency, clumping, frosting, or precipitation 1
• Insulin in use may be kept at room temperature to reduce local irritation from cold insulin 1
• Always maintain a spare bottle of each insulin type 1

Visual Inspection

• Inspect the bottle before each use—Mixtard should appear uniformly cloudy 1
• Discard if you observe clumping, frosting, precipitation, or changes in clarity or color indicating loss of potency 1

Critical Considerations

Mixing Restrictions

• Do not mix Mixtard with any other insulin or medication unless specifically approved by the prescribing physician 1
• Premixed insulins like Mixtard eliminate the need for self-mixing, providing increased dosing accuracy and convenience 2, 9

Special Populations

• Mixtard has been successfully used in children and adolescents aged 6-18 years with type 1 diabetes 3
• In elderly patients, premixed insulins may offer advantages in terms of ease of use and compliance 9

Common Pitfalls to Avoid

• Never change insulin types or brands without medical supervision, as this requires additional glucose monitoring and potential dose adjustments 1
• Do not use commercially available premixed insulins if the ratio does not match the patient's individual insulin requirements 1
• Avoid injecting into areas of lipohypertrophy, as this causes slower and more variable absorption 1
• Do not administer intramuscularly, as this causes faster absorption and is not recommended for routine use 1

Hypoglycemia Risk Factors

• Excess insulin, delayed or missed meals, decreased carbohydrate intake, increased physical activity, or increased insulin absorption rates (from heat exposure or hot water) can cause hypoglycemia 1
• All insulin-requiring individuals should carry at least 15g of carbohydrate for treating hypoglycemia 1

Needle Disposal

• Remove and dispose of needles in puncture-resistant containers after each injection without recapping 1, 5
• Follow local regulations for sharps disposal 1