Protaphane

What Is Protaphane and What Is It Used For?

Protaphane is an intermediate-acting human NPH insulin suspension used to treat diabetes mellitus. It provides a slow, steady release of insulin over up to 24 hours, serving as a basal (background) insulin to keep blood glucose stable between meals and overnight. It is prescribed for adults, adolescents, and children aged 2 years and above with type 1 or type 2 diabetes.

Diabetes mellitus is a chronic metabolic disorder characterised by persistently elevated blood glucose levels. In type 1 diabetes, the immune system destroys the insulin-producing beta cells of the pancreas, leading to an absolute deficiency of insulin. In type 2 diabetes, the body becomes resistant to the effects of insulin and the pancreas cannot produce enough to overcome this resistance. Insulin therapy, including basal insulins such as Protaphane, is essential in type 1 diabetes and is often required in advanced type 2 diabetes, gestational diabetes, and certain other forms of diabetes.

Insulin is a hormone produced by the beta cells of the pancreas. It facilitates the uptake of glucose from the bloodstream into muscle, liver, and fat cells, where glucose is used as fuel or stored for later use. Insulin also suppresses the production of glucose by the liver (gluconeogenesis and glycogenolysis) and promotes the synthesis of proteins and fats. Without sufficient insulin activity, blood glucose rises to harmful levels, leading to short-term symptoms such as fatigue, excessive thirst, and frequent urination, and to long-term complications affecting the eyes, kidneys, nerves, heart, and blood vessels.

Protaphane contains human insulin that is structurally identical to the insulin made by the human pancreas. It is produced using recombinant DNA technology in baker's yeast (Saccharomyces cerevisiae). The suffix “isophane” refers to the Neutral Protamine Hagedorn (NPH) formulation, in which protamine sulfate and zinc are combined with insulin to form small crystals. These crystals dissolve gradually after subcutaneous injection, which delays and prolongs the absorption of insulin into the bloodstream. As a result, Protaphane has a time-action profile markedly different from that of soluble or rapid-acting insulins.

After subcutaneous injection, Protaphane begins to lower blood glucose within approximately 1.5 hours. The maximum (peak) blood glucose-lowering effect occurs between 4 and 12 hours, and the total duration of action is up to 24 hours. This pharmacokinetic profile makes Protaphane suitable as a basal insulin – providing background coverage to control fasting and pre-meal blood glucose, to suppress hepatic glucose production overnight, and to maintain stable glycaemic control when combined with rapid-acting or short-acting mealtime insulins.

In clinical practice, Protaphane is most often used as part of a basal-bolus insulin regimen in type 1 diabetes, typically in combination with a rapid-acting insulin analogue (such as insulin aspart) taken before meals. In type 2 diabetes, Protaphane may be used as add-on therapy to oral antidiabetic medicines (such as metformin) or as part of a combined insulin regimen. Your doctor will determine the most appropriate regimen based on your individual blood glucose targets, lifestyle, diet, and overall health status.

What Should You Know Before Taking Protaphane?

Before starting Protaphane, inform your doctor about all medical conditions you have, all medicines and supplements you take, and lifestyle factors such as alcohol use, exercise habits, and travel plans. Several conditions and drugs can alter your insulin requirements, and dose adjustments may be necessary to maintain safe and effective blood glucose control.

Contraindications

Do not use Protaphane if you are currently experiencing an episode of hypoglycaemia (low blood sugar). Administering additional insulin during hypoglycaemia will drive blood glucose even lower, which can be life-threatening. Wait until your blood sugar has returned to a safe level and you have eaten a carbohydrate-containing meal before resuming your usual insulin schedule.

Do not use Protaphane if you are hypersensitive (allergic) to human insulin or to any of the excipients in the formulation. The excipients include protamine sulfate, zinc chloride, glycerol, metacresol, phenol, dibasic sodium phosphate dihydrate, sodium hydroxide, hydrochloric acid, and water for injections. Allergic reactions can range from localised skin reactions to severe, potentially life-threatening anaphylaxis.

Protaphane is for subcutaneous use only. It must never be injected intravenously or intramuscularly. Intravenous injection of an NPH insulin can cause severe, rapid-onset hypoglycaemia. Protaphane is also not suitable for use in insulin infusion pumps, as the suspension can block the pump tubing. If you need continuous subcutaneous insulin infusion, your doctor will prescribe a soluble insulin appropriate for pump use.

Warnings and Precautions

Several situations may alter how your body responds to Protaphane and require vigilant monitoring. Insufficient dosing, missed injections, illness (particularly with fever), significant overeating, or discontinuation of insulin therapy can lead to hyperglycaemia and, in people with type 1 diabetes, diabetic ketoacidosis (DKA). Early warning signs of hyperglycaemia include increased thirst, frequent urination, fatigue, nausea, loss of appetite, flushed skin, and fruity-smelling breath. If these symptoms appear, check your blood glucose and blood or urine ketones and contact your healthcare provider promptly.

Hypoglycaemia is the most common adverse reaction to any insulin, including Protaphane. It can develop rapidly if the dose is too high for the prevailing insulin requirement, if a meal is skipped or delayed, if exercise is unplanned or especially strenuous, or if alcohol is consumed on an empty stomach. Patients who have had diabetes for many years or who maintain very tight glycaemic control may develop hypoglycaemia unawareness, in which the typical warning symptoms are blunted. This significantly increases the risk of severe hypoglycaemia. Discuss any changes in your ability to detect hypoglycaemia with your diabetes team, as your treatment plan may need adjustment.

Kidney and liver disease can both affect how your body handles insulin. In renal or hepatic impairment, insulin clearance is reduced, which prolongs its action and increases the risk of hypoglycaemia. Dose reductions and more frequent blood glucose monitoring may be needed. Your doctor may also consider lower glycaemic targets to reduce the risk of dangerous lows, particularly if you have been hospitalised, are severely unwell, or are approaching the end of life.

Thyroid disease, adrenal insufficiency, and disorders of the pituitary gland can change insulin requirements unpredictably. If you have any of these conditions or start treatment for them, close monitoring of blood glucose is essential. Similarly, significant changes in diet, physical activity, body weight, or stress can alter how much insulin you need. If you are travelling across time zones, work with your diabetes team well in advance to plan dose timing adjustments.

Patients with type 2 diabetes who are at cardiovascular risk and take insulin in combination with pioglitazone should be monitored for signs of heart failure. Report any unexpected shortness of breath, rapid weight gain, or swelling of the ankles (oedema) to your doctor immediately. In some cases, discontinuation of pioglitazone may be required.

Pregnancy and Breastfeeding

Maintaining good blood glucose control before and during pregnancy is essential to protect both the mother and the developing baby. Poorly controlled diabetes increases the risk of miscarriage, congenital malformations, stillbirth, and neonatal complications. Protaphane can be used safely during pregnancy and has a long record of use in pregnant women with diabetes. Insulin does not cross the placenta in clinically meaningful amounts.

Insulin requirements change dynamically during pregnancy. In the first trimester, insulin needs typically decrease, and the risk of hypoglycaemia is elevated. During the second and third trimesters, insulin resistance rises markedly and insulin doses usually need to be increased substantially. After delivery, insulin requirements often return rapidly to pre-pregnancy levels, and another dose adjustment is required to prevent hypoglycaemia.

If you are planning a pregnancy or are already pregnant, seek specialist advice from a diabetes care team experienced in managing diabetes in pregnancy. Frequent blood glucose self-monitoring, continuous glucose monitoring where available, and regular antenatal follow-up are all recommended.

Protaphane can also be used during breastfeeding. Insulin is a protein and is broken down in the baby's digestive tract, so it is not absorbed in active form through breast milk. However, breastfeeding increases caloric expenditure and can affect blood glucose levels, so the insulin dose and dietary intake may need adjustment.

Driving and Operating Machinery

Hypoglycaemia impairs concentration and reaction time and can pose a serious risk when driving or operating machinery. Always check your blood glucose before driving, particularly on long journeys, and do not drive if your blood glucose is low or if you feel any symptoms of hypoglycaemia such as dizziness, shaking, confusion, or sweating. Keep fast-acting glucose (tablets, gel, or a sugary drink) within easy reach in your vehicle. If you experience frequent hypoglycaemia or reduced awareness of warning signs, discuss with your doctor whether it is safe for you to drive, and follow the licensing regulations in your country.

How Does Protaphane Interact with Other Drugs?

Many medications can alter the blood glucose-lowering effect of Protaphane. Some increase the risk of hypoglycaemia, while others reduce insulin's effectiveness and may cause hyperglycaemia. Always tell your doctor and pharmacist about every prescription medicine, over-the-counter product, herbal remedy, and supplement you use, so that insulin doses can be safely adjusted.

Drug interactions with insulin are clinically important because they can shift glucose control in either direction. Some medications potentiate insulin's hypoglycaemic effect, increasing the risk of dangerously low blood sugar. Others antagonise insulin, contributing to hyperglycaemia and poor diabetes control. A third category – including some beta-blockers – may mask the adrenergic warning symptoms of hypoglycaemia, making it harder to recognise and treat low blood sugar promptly.

Major Interactions

The following medications have the most clinically significant interactions with Protaphane. Dose adjustments are frequently required when starting, stopping, or changing the dose of any of these drugs:

Additional Interactions and Cautions

Other medications also deserve attention. Sympathomimetics (such as adrenaline/epinephrine, salbutamol, and terbutaline), growth hormone, danazol, and atypical antipsychotics such as olanzapine and clozapine can raise blood glucose and reduce the effectiveness of insulin. Octreotide and lanreotide may either increase or decrease insulin requirements unpredictably and require frequent monitoring. Pioglitazone combined with insulin increases the risk of fluid retention and heart failure in susceptible patients.

Beta-Blockers: A Special Consideration

Beta-blockers (such as propranolol, atenolol, bisoprolol, or metoprolol) warrant particular attention because they can both alter blood glucose and mask the typical adrenergic warning signs of hypoglycaemia. Specifically, beta-blockers may suppress the tachycardia and tremor that many people rely on to detect falling blood sugar. If you are prescribed a beta-blocker alongside Protaphane, monitor blood glucose more frequently and learn to recognise non-adrenergic symptoms of hypoglycaemia such as confusion, difficulty concentrating, visual disturbances, and excessive hunger. Cardioselective beta-blockers (such as bisoprolol and metoprolol) tend to interfere less with hypoglycaemia recognition than non-selective agents, but caution is still warranted.

Thiazolidinediones, somatostatin analogues, and atypical antipsychotics can also have variable effects on insulin sensitivity. Cannabis and herbal products (including St John's wort, ginseng, and chromium) can affect glucose control in some patients. Always inform your diabetes team about any complementary or alternative medicines you take.

What Is the Correct Dosage of Protaphane?

The dose of Protaphane is strictly individualised based on your blood glucose levels, type of diabetes, other medications, diet, body weight, and level of physical activity. Your doctor will calculate and titrate the dose based on regular blood glucose monitoring and HbA1c results. Never adjust your dose without medical guidance.

Insulin dosing is one of the most individualised aspects of diabetes therapy. There is no single correct dose of Protaphane – your healthcare team will determine the dose that best controls your blood glucose based on home blood glucose readings, structured self-monitoring, and periodic laboratory tests such as HbA1c. Dosing depends on the type of diabetes, concurrent use of other insulins and oral antidiabetic medicines, body weight, diet, exercise, illness, and individual sensitivity to insulin. The information below is for educational purposes and should not replace the dosing guidance given by your doctor.

Adults

Children and Adolescents

Elderly Patients

How to Prepare and Inject Protaphane

Protaphane must be resuspended before every injection so that the insulin is evenly distributed throughout the liquid. Injecting an inadequately mixed suspension can result in significant under- or overdosing. Follow these steps:

1. Wash your hands and prepare a clean injection site. Check the label to confirm you have the correct insulin, strength, and expiry date.
2. Resuspend the insulin: Roll the FlexPen, InnoLet, Penfill cartridge, or vial gently between your palms 10 times. Then tip it upside down and back 10 times. The suspension should appear uniformly cloudy and white. Do not use the insulin if it looks clear, if it contains lumps, or if white particles remain stuck to the walls or bottom of the container.
3. Attach a new needle and prime the pen by dialling 2 IU, holding the pen with the needle pointing upward, and pressing the injection button until a drop appears at the needle tip. Repeat if necessary.
4. Dial your prescribed dose carefully. Check the dose window before injecting.
5. Choose and clean the injection site: The abdomen, thigh, buttock, or upper arm are all acceptable. Rotate within each area to prevent skin changes. Cleaning is usually with a dry tissue or alcohol swab, as advised by your healthcare provider.
6. Inject subcutaneously: Pinch the skin if recommended and insert the needle at the angle your nurse has shown you. Press the injection button fully and keep the needle under the skin for at least 6 seconds after the dose counter returns to zero, to ensure the full dose is delivered.
7. Remove the needle carefully and dispose of it in a sharps container. Replace the pen cap. Never share pens or needles with another person, even if the needle has been changed – this carries a risk of blood-borne infection transmission.

Missed Dose

If you miss a dose of Protaphane, your blood glucose may rise. Measure your blood glucose as soon as you remember and follow your diabetes care team's sick-day or missed-dose guidance. In general, do not take a double dose to make up for a missed injection, as this can cause hypoglycaemia. If you are unsure how to manage a missed dose, contact your diabetes specialist nurse, doctor, or pharmacist for advice.

Overdose

What Are the Side Effects of Protaphane?

Like all medicines, Protaphane can cause side effects, although not everyone experiences them. Hypoglycaemia (low blood sugar) is by far the most common side effect and the main clinical risk. Local reactions at injection sites, skin changes, oedema, and rare systemic allergic reactions are also possible. Understanding these risks helps you recognise and manage them promptly.

The adverse effects of Protaphane are largely shared with other insulin preparations and relate to the pharmacological action of insulin itself and the subcutaneous mode of administration. The most clinically important adverse reaction is hypoglycaemia, which can range from mild and easily self-treated to severe and life-threatening. Frequencies below are based on pooled clinical trial and post-marketing data for human NPH insulins.

If you experience any signs of a systemic allergic reaction (widespread rash, difficulty breathing, swelling of the face, lips or throat, rapid heartbeat, drop in blood pressure, or fainting), seek emergency medical attention immediately. These reactions are extremely rare but can be life-threatening.

Oedema (swelling of the ankles, feet, or hands due to fluid retention) can occur, particularly when insulin therapy is initiated or intensified. This is usually temporary and resolves as the body adjusts to improved glycaemic control. Temporary blurred vision may also occur during the first days or weeks of insulin therapy because lens hydration changes with blood glucose; no optical prescription change is usually needed, and vision normally stabilises within a few weeks.

Managing Hypoglycaemia

Hypoglycaemia occurs when blood glucose falls below approximately 3.9–4.0 mmol/L (70–72 mg/dL). Common causes include taking too much insulin, skipping or delaying meals, exercising more than usual, drinking alcohol, being unwell (particularly with vomiting or diarrhoea), or injecting into a site with altered absorption (such as a lipohypertrophic lump).

For mild to moderate hypoglycaemia, follow the “15–15 rule”:

1. Immediately consume 15–20 grams of fast-acting carbohydrate (e.g. 3–4 glucose tablets, 150 ml fruit juice, or a small sugary drink).
2. Wait 15 minutes and recheck your blood glucose.
3. If still below target, repeat the fast-acting carbohydrate.
4. Once blood glucose normalises, eat a longer-acting carbohydrate snack (sandwich, biscuits, fruit) to prevent recurrence, especially if the next meal is more than an hour away.

Severe hypoglycaemia – characterised by confusion, loss of consciousness, or seizures – is a medical emergency. It requires immediate glucagon injection by a trained companion and contact with emergency services. Every person using insulin should carry an identification card or medical alert bracelet stating that they have diabetes and use insulin, and should ensure that family, close friends, and colleagues know how to recognise and respond to severe hypoglycaemia.

Managing Hyperglycaemia and Diabetic Ketoacidosis

Hyperglycaemia (high blood sugar) can occur if you miss insulin doses, take less than prescribed, eat significantly more than your meal plan allows, are acutely unwell, or are under stress. Symptoms develop gradually over hours or days and include increased thirst, frequent urination, fatigue, drowsiness, loss of appetite, flushed face, fruity-smelling breath, nausea, and vomiting.

In people with type 1 diabetes, untreated hyperglycaemia can progress rapidly to diabetic ketoacidosis (DKA), a life-threatening condition. DKA is characterised by deep, rapid breathing, a fast pulse, severe dehydration, and abdominal pain. It requires immediate medical treatment with intravenous fluids, insulin, and electrolyte replacement. If you develop symptoms of DKA or if your blood or urine ketones are significantly elevated, seek emergency medical care without delay.

How Should You Store Protaphane?

Correct storage of Protaphane is essential to preserve its effectiveness. Unopened vials, cartridges, and pens should be refrigerated at 2–8°C away from the cooling element. Once in use, store below 30°C and use within 6 weeks. Never freeze insulin and never store the in-use pen in the refrigerator.

Keep Protaphane out of the sight and reach of children at all times. Store unopened vials, Penfill cartridges, FlexPens, or InnoLets in a refrigerator at 2–8°C (36–46°F). Place them in the main body of the refrigerator rather than against the back wall or in the freezer compartment. Never freeze insulin; frozen insulin loses its effectiveness and must be discarded.

The cartridge, pen, or vial that you are currently using should be stored at room temperature, not exceeding 30°C (86°F), and should be used within 6 weeks of first use (always check the specific product leaflet, as in-use periods can differ slightly between presentations). Do not return the in-use device to the refrigerator, as temperature fluctuations can affect dose consistency and promote crystal formation.

Protect insulin from direct heat, direct sunlight, and extreme cold. Do not leave it in a hot car, on a windowsill, or on top of heating appliances. Do not carry it in checked luggage when flying, because the cargo hold can reach freezing temperatures; carry it in your hand luggage with a doctor's note if required. When travelling in hot climates, use an insulated pouch or cooling wallet to keep your insulin within the recommended temperature range.

Before each injection, inspect the suspension visually. After proper resuspension, Protaphane should look uniformly cloudy and white. Do not use it if the suspension contains lumps, if solid white particles stick to the bottom or walls of the container giving a frosted appearance, or if the product fails to become uniformly cloudy after gentle mixing. Once clumping has occurred, the insulin should be discarded.

Always check the expiry date printed on the label and carton before use. Do not use Protaphane after the expiry date, which refers to the last day of the stated month. Dispose of expired or unused insulin and used needles according to local regulations – do not throw them in household waste or flush them down the drain. Many pharmacies offer sharps and medicine disposal services. Ask your pharmacist for local guidance.

What Does Protaphane Contain?

Protaphane contains human insulin as its active substance, produced using recombinant DNA technology in yeast. It also contains several excipients that extend the duration of action, buffer the pH, prevent microbial growth, and maintain the correct tonicity.

The active substance is human insulin (rDNA origin), produced in the baker's yeast Saccharomyces cerevisiae using recombinant DNA technology. The resulting insulin is structurally identical to the insulin produced by the human pancreas, distinguishing it from older animal-derived insulin preparations. Each millilitre contains 100 international units (IU) of human insulin in the standard 100 IU/ml presentation, or 40 IU/ml in certain regional products where that strength is still available.

The other ingredients (excipients) in Protaphane are:

• Protamine sulfate – forms crystalline complexes with insulin to delay absorption and extend the duration of action (this is what makes it an “NPH” insulin)
• Zinc chloride – stabilises the insulin hexamer structure
• Glycerol – tonicity agent that keeps the solution isotonic with body tissues
• Metacresol – antimicrobial preservative
• Phenol – antimicrobial preservative
• Dibasic sodium phosphate dihydrate – buffering agent to maintain pH stability
• Sodium hydroxide – used during manufacture for pH adjustment
• Hydrochloric acid – used during manufacture for pH adjustment
• Water for injections – solvent

Protaphane contains less than 1 mmol sodium (23 mg) per dose and is therefore considered essentially sodium-free. Each Penfill cartridge contains 300 IU (3 ml) of insulin suspension, and each FlexPen and InnoLet contains 300 IU (3 ml). Vials typically contain 1,000 IU (10 ml). Pack sizes vary by country; typical packaging contains 1 vial of 10 ml, or multipacks of 5 Penfills, FlexPens or InnoLets.

Protaphane is manufactured by Novo Nordisk A/S, a pharmaceutical company with long-standing expertise in insulin production. It is approved in many countries worldwide and may be marketed under slightly different brand names in different regions (for example, Insulatard in some markets). Always verify the name and strength of your insulin when it is dispensed.

Frequently Asked Questions About Protaphane