More long term therapies are likely to be required in the future that can be self-administered safely. Helge Adleff, managing director, Acuros, describes a device offering constant delivery of small volume parenteral drugs for the outpatient market.
After the medicines themselves, the method of drug delivery is the next most critical parameter for the success of a medical therapy. For some patients, continuous drug administration can have many advantages over repeated bolus (pills or injections) dosage forms, including the prevention of over- or under- dosing.
For example, excess drug plasma levels, which may occur immediately after injections, can promote undesirable side effects. A short time later the drug plasma level can drop below its optimum, followed by low therapeutic efficacy. Furthermore, many new biotech drugs can be administered only by bypassing the digestive tract and therefore require continuous parenteral delivery.
To address this need, stationary infusion devices are widely used in hospital environments where patients are under intensive care. But if an ambulatory patient is in need of sustained drug delivery or a patient needs to take their medication at home, what options are open to them?
For these patients there are currently few options available. Among the best known are portable, battery driven insulin pumps. These costly devices are usable by a small group of Type I diabetic patients only. They offer the advantages of sustained insulin delivery with unlimited mobility, thus improving a patient’s quality of life. However, there is a lack of cost-effective, safe and easy-to-use devices for continuous delivery of small volume parenteral drugs for the outpatient market.
Patients who would benefit from such a device include those needing treatment for Type II diabetes, cancer or pain management. A discreet portable pump can offer these patients the best medication without restricting their way of life or setting boundaries to mobility.
Acuros, a German spin-out from Humboldt University, Berlin, has developed a single-use device, designed for the sustained delivery of any liquid drug formulation. The portable pump can be set to infuse the drug at a constant rate for a prolonged time – up to several days.
Once the pump is started and connected to the infusion set it requires no further attention and can be taken anywhere by the patient. A window on the device allows visible control of the flow and the pump stops when the infusion is completed.
osmosis for drug delivery
The newly developed micro pump is driven by an osmotic actuation and therefore runs without a battery or power supply and contains no electronic or mechanical components. Hence, the pump is produced at low cost and does not give rise to environmental concerns. Because no battery or electronic components are involved, disposal of the single use unit is safe and ecological. This device optimises medical care without restricting the patient’s mobility or requiring huge investment.
Although the device is simple enough for single use, it offers precise and constant flow rates throughout the entire delivery process. The preset rate is in the range of microlitre to millilitre per hour – enabling constant parenteral drug delivery for hours, days or weeks.
In contrast to other disposable pumps, the Acuros device takes advantage of standard cartridges and syringes for primary packaging and is therefore suitable for any liquid drug formulation. Pharmaceutical companies can continue to use their approved packaging, avoiding any extra burden of primary packaging validation.
how it works
Osmosis is a well understood natural phenomenon that occurs when a diluted solution and a concentrated solution are separated by a semi-permeable membrane. The solvent (usually water) flows through the membrane from the side of low concentration to the side of higher concentration, following the osmotic pressure gradient. This flow is osmotically induced and requires no further power supply. Due to the osmotic process, the concentrated solution becomes more dilute and the flow rate decreases and so common osmotic flows do not show a stable flow rate.
Figure 1: Delivery regime and drug plasma level over time
With the Acuros osmotic pump, the dilution of osmolyte is compensated for by a self-sustaining process that keeps the osmotic pressure constant throughout the entire application. This enables a stable flow rate of medicine, independent of viscosity, back pressure and power supply. The flow rate will remain constant at its preset level until all content from the drug reservoir has been pumped. The pump will stop automatically when the delivery is completed.
Through osmosis, fluid pushes on the plunger in the glass syringe driving the drug formulation through the syringe opening. The osmotic-acting fluid and the drug formulation are separated by the plunger, such that no mixing of fluids occurs. The osmotic actuation is independent of the drug formulation. The device contains all required components and is ready to use.
The actuation and invention are covered by international patents held by Acuros.