Insulin isophane (NPH)

Selected Humulin N and Novolin N improve glycemic control in adults and children with diabetes mellitus. They are human insulin combined with protamine for intermediate action. Type 1 treatment generally also needs prescribed prandial insulin; NPH alone is not a complete universal basal/prandial regimen.

Selected U-100 suspension is for subcutaneous injection only. Neither product is for IV use or an insulin pump. This review does not provide a DKA, pregnancy, inpatient, neonatal or insulin-to-insulin conversion algorithm, and does not substitute NPH for separately named premixed products.

Both labels require individualization using glucose monitoring and clinical goals, with reassessment for illness, meals, activity, weight, medicines and organ-function changes. Novolin N specifically allows once- or twice-daily dosing; Humulin N does not give a single fixed frequency or universal starting-unit algorithm. Do not independently change brand, strength or timing.

Use abdomen, thigh, upper arm or buttocks, rotating sites within the same region. Avoid pits, thickened skin, lumps, scars and damaged sites. Use a U-100 syringe for vials; both selected pens dial one-unit increments and deliver 1–60 units per injection. Pen maximum per injection is a device limit, not a daily-dose ceiling. Get a written plan for doses requiring multiple injections; do not count clicks to measure a dose.

Humulin N vial: gently roll and invert at least ten times each; KwikPen: roll ten times and invert ten times. Novolin N vial: roll horizontally ten times until uniformly cloudy; FlexPen PI specifies twenty up/down movements, while its IFU distinguishes first-use twenty from subsequent at least ten. Follow the exact device’s current instructions and training; no vigorous shaking. Do not use clear, clumped, discolored or particulate suspension.

Only mix insulin when prescribed and trained using vial/syringe technique. Humulin N allows Humulin R or Humalog, drawing the short/rapid-acting product first and injecting immediately. Novolin N allows only Novolin R in the same syringe, drawn first, with immediate injection. Do not mix inside a pen or infer compatibility with another basal insulin or unreviewed product.

Renal/hepatic impairment increases hypoglycemia risk and may require more frequent adjustment and glucose monitoring. Neither label supplies an eGFR reduction or dialysis supplemental-unit table. Switching manufacturer/type/site requires close supervision and intensified monitoring, especially when moving away from abnormal injection sites.

Do not administer during an episode of hypoglycemia or after hypersensitivity to the product/ingredients. A low-glucose episode requires the agreed rescue and reassessment plan; do not interpret this as permission to permanently stop essential insulin without clinical direction.

Neither selected current PI has a boxed warning. Severe hypoglycemia, anaphylaxis, hypokalemia and unsafe sharing remain potentially life-threatening despite absence of a box.

Hypoglycemia is common. Injection-site allergy, lipodystrophy, localized amyloidosis, edema, weight gain and antibodies are described. Novolin N additionally describes temporary refractive changes, worsening retinopathy and painful neuropathy during rapid glucose-control intensification; these reports do not mean long-term glucose control should be abandoned. Serious generalized allergy is possible and frequencies are not uniformly estimable.

Other glucose-lowering agents, ACE inhibitors/ARBs, fibrates, fluoxetine, MAO inhibitors, salicylates and sulfonamide antibiotics can increase glucose-lowering effect. Dose adjustment and more frequent glucose checks may be needed; no universal percentage reduction is established.

Corticosteroids, thyroid hormones, sympathomimetics, atypical antipsychotics, some diuretics and hormonal products can oppose glucose lowering. Alcohol, beta-blockers, clonidine and lithium can shift effect in either direction; pentamidine may cause low glucose followed by high glucose. Labels counsel avoiding alcohol and reviewing the entire regimen rather than relying on spacing.

Beta-blockers, clonidine, guanethidine and reserpine can blunt hypoglycemia warnings; increase objective monitoring as appropriate. Pioglitazone/other TZDs with insulin can cause fluid retention and heart failure: monitor dyspnea, swelling and rapid weight gain; clinician-directed TZD reduction/discontinuation may be necessary.

Both are labeled for pediatric diabetes without a single universal age/weight dosing table. Novolin N specifically stresses frequent pediatric glucose checks. Older adults have greater hypoglycemia concern from comorbidity/polypharmacy; age effects on PK/PD are unstudied. Device assistance is essential with visual impairment; audible clicks are not a dose-reading substitute.

PK/PD effects of these impairments are unstudied in the selected labels, but low-glucose risk is greater. Adjust using clinical response and glucose data, including during changing organ function. No numeric renal/hepatic reduction or hemodialysis algorithm is supplied.

Decades of human-insulin data have not established association with major birth defects, miscarriage or adverse maternal/fetal outcomes, but study limitations prevent proving absence of risk. Poorly controlled diabetes itself carries substantial maternal/fetal risk. Use an individualized pregnancy glucose-control plan rather than independently stop insulin or apply a universal NPH pregnancy dose.

Published evidence suggests human insulin can enter milk; infant adverse reactions have not been reported in the literature reviewed by these labels. Effects on milk production are unknown. Consider maternal need and feeding benefits with individualized glucose monitoring/dose adjustment; do not claim milk transfer is absent.

Human insulin increases muscle/fat glucose uptake and suppresses hepatic glucose production, lipolysis and proteolysis. Humulin N healthy-volunteer testing found median maximum glucose-lowering effect at 6.5 hours, with wide variability. Novolin N describes onset about 1–2 hours and variable action lasting up to 24 hours. These product-specific observations are guides, not guaranteed personal curves or reasons to omit meals/monitoring.

Insulin is degraded mainly in liver, kidney, muscle and adipose tissue. Humulin N serum peak in a volunteer study was around four hours, also highly variable; absorption-limited kinetics prevent a reliable true half-life estimate from the terminal curve. Population/organ-function effects are inadequately studied. No serum insulin level target replaces glucose-guided treatment.

Follow glucose results and individualized HbA1 c goals, symptoms, injection sites, meal/activity patterns, organ-function changes and interacting drugs. Increase checks during changes and impaired awareness; check potassium if at risk. Review sick-day, missed-dose, travel, driving and supply plans with the diabetes team; this page supplies no independent titration algorithm.

Use oral glucose for a mild episode when awake and able to swallow, following the agreed plan. Coma, seizure or inability to swallow requires emergency help and trained glucagon use/medical IV glucose; do not give oral food to an unconscious person. Recurrent low glucose can require continued observation and carbohydrate after recovery. Seek care for severe allergy or heart-failure symptoms.

Use a new compatible needle and prime before each injection, read units in the dose window and remove the needle afterward. Humulin KwikPen holds the button/needle in place while counting five slowly; Novolin FlexPen requires at least six seconds. Do not automatically repeat an uncertain injection. Use approved sharps disposal and never share or refill the single-patient pen.

Humulin N 10 mL vial NDC 0002-8315-01; five 3 mL KwikPens NDC 0002-8805-59. Novolin N 10 mL vial NDC 0169-1834-11; five 3 mL FlexPens NDC 0169-3004-15, with separately labeled ReliOn packages. Confirm the exact package and NPH label before every dose.

Both selected products are uniformly white/cloudy U-100 suspensions in a 10 mL multidose vial or 3 mL single-patient pen (300 units). Neither is U-500 regular insulin, rapid-acting insulin or 70/30 premix. Their protamine/preservative ingredients and devices differ; switching requires clinical review.

Unopened refrigerated products: 2–8°C until labeled expiry; never freeze and protect from heat/light. Humulin N vial: 31 days after first use, refrigerated or ≤ 30°C; total room-temperature time including unopened time is also capped at 31 days. Humulin KwikPen: 14 days total room-temperature time at ≤ 30°C; do not refrigerate in use. Novolin N vial: 42 days at ≤ 25°C unopened at room temperature or after first use; do not refrigerate in use. Novolin FlexPen: 28 days at ≤ 30°C, including unopened room-temperature allowance; do not refrigerate in use. Record dates and use the earlier applicable expiry; do not import another insulin’s 28-day rule.