Issue:October 2012

DRUG DEVICES – The Rise of the Bolus Injector – A New Device Class Enabling Long-Duration Subcutaneous Administration of Large-Dose Volume Biologics

The commercial potential of many biologics has until now been constrained by their very nature. A new class of wearable, disposable devices known as bolus injectors has been developed to address emerging market needs for the subcutaneous delivery of biologics requiring dose volumes greater than 1 mL.

A fundamental challenge facing pharmaceutical companies developing monoclonal antibodies, peptides, and other emerging biologics has been to find the right formulation balance between viscosity and volume. Too viscous, and the pressure for a subcutaneous injection becomes too great for the use of a standard prefilled syringe or auto-injector. Drug safety and efficacy issues relating to aggregation may also arise in which the concentration of a liquid formulation is too high.

Too much volume, and there is a high risk of compromising the subcutaneous layer’s capacity to absorb more than 1mL of drug over a standard injection period of several seconds. Attempts to force the subcutaneous injection of large volume doses can be painful to a patient, creating risks such as tissue distortion, edema, irritation, or redness. Therapy compliance may also be affected when patients must hold a device optimally at the injection site for more than 15 seconds due to a natural loss of attention and a likely change in angularity.

For biologics that can attain a liquid dose volume of 1mL or less, there are attractive commercial opportunities to gain approval for subcutaneous self-administration by the patient in a prefilled syringe or auto-injector format. However, an estimated 15% and 20% of all biologics now in clinical development will need to be formulated in a concentration in which the dose volume is greater than 1ml, and delivery periods make the use of a hand-held device unfeasible.

Some pharmaceutical and biotechnology companies have found some level of compromise by securing approval for their large-dose volume molecules to be delivered via IV administration in a healthcare facility or clinic. However, many other highly promising pipeline molecules won’t reach patients until a suitable delivery system is identified that can enable their commercialization for patient subcutaneous self-administration.


With so many biologics in clinical development or approved and requiring lifecycle management to improve or protect market share, the development of wearable, disposable delivery systems for the subcutaneous delivery of large-dose volume drugs is considered by many to be one of the greatest unmet needs in the pharmaceutical industry today. Several device manufacturers, including Unilife, have developed a new class of devices to address the primary container, dose delivery, and patient needs of these largevolume biologics. Once called patch pumps or micro-pumps, these devices are now increasingly referred to as bolus injectors.

There are many fundamental differences between the traditional pump-based devices used for insulin and those required for the delivery of biologics. Insulin pumps are a highly effective and patient-friendly delivery system for providing therapy for diabetics. But they are far too complex and expensive for the delivery of biologics, which only require the administration of a standardized dose to the patient on a periodic basis.

Until recently, it was impossible for a pharmaceutical company to access a disposable device technology that could facilitate the self-administration of a bolus or rate-based therapy with a dose volume greater than 3 mL. In one recent case, a pharmaceutical company required a device to deliver a biologic with a 6 mL dose volume. A device manufacturer advised them to use two 3-mL pumps for attachment onto the patient at the same time. Understandably, the pharmaceutical company pursued other opportunities to identify a device platform that could address its specific needs.

A bolus injector represents a very distinct and separate device classification to insulin pumps, which naturally warrant a higher level of regulatory scrutiny because of their need to precisely deliver a variable dose. By contrast, the role of a bolus injection system is to deliver a standardized dose volume into the subcutaneous layer over a designated period of time. It is designed to be either worn on the body, or attached onto the belt of the patient, for the period of dose delivery. After the completion of the full dose, the device is removed from the body and disposed.

While bolus injectors are primarily designed for use with molecules with dose volumes greater than 1 mL, they are also ideal for therapies with lower-dose volumes and a high viscosity, which are better suited to subcutaneous injection over a period of 30 seconds or more.


Bolus injectors create several significant commercial opportunities for pharmaceutical companies developing biologics and other large-dose volume drugs. They can help to enable the clinical development of pipeline drugs in larger dose volumes that avoid the aggregation and patient discomfort risks associated with high concentrations. They offer compelling lifecycle management opportunities to transition approved drugs that are currently indicated for IV infusion into a subcutaneous injection format. They can also help a drug generate significant brand differentiation against competitors within a therapeutic class, or potentially expand the number of indications of which it may be prescribed.

With so many biologics and other large dose volume drugs now being considered for use with bolus injectors, Unilife expects this new and fast-growing device market will be valued at more than $500 million within a few short years. Bolus injection systems create many compelling benefits for pharmaceutical companies, patients, payers and prescribers.

Many pharmaceutical companies now recognize the significant potential of bolus injectors to enable or enhance the delivery of biologic therapies across a range of acute and chronic conditions, including auto-immune diseases, central nervous system, infectious diseases, and oncology.

For patients, they can improve quality of life, generate greater independence, and encourage greater therapy convenience and compliance. Payors can leverage these improved rates of compliance and continuation to transition healthcare from the healthcare facility to the home, which will significantly reduce treatment-related costs. The safety and simplicity of these devices can also mean more prescribers can administer a drug for use.


Unilife, a US-based developer, manufacturer, and supplier of innovative, differentiated devices for injectable drug delivery, has quickly attained a leadership position within this new and fast-growing market sector. It has developed a comprehensive platform of bolus injecors to simplify the commercial development and patient delivery of biologics between 1 mL and 30 mL in volume.

In recognition of the fact that every customer, drug, and target patient population has specific requirements, Unilife has created a platform that combines simplicity and flexibility.

One of the fundamental requirements established upfront by Unilife in the development of its bolus injector technology injectors feature a primary container made of standard USPcompliant materials in the fluid path. They are also designed for supply to customers ready for integration into regular filling lines.

The goal of Unilife during every program with a pharmaceutical customer is to enable the target patient to get on with their lives with minimal inconvenience during the period of dose administration. Steps of use must be as intuitive as possible. The device footprint from a height, width, and contour perspective must also be minimal. As a result, every Unilife bolus injector is not only very compact, sleek, and elegant in design, but incorporates human factor engineering so that it is tailored to address the specific needs of the target patient population. External customization options include the contoured shape of the device, the number or position of the activation buttons, and color configurations. The steps of use for a Unilife bolus injector are highly intuitive for patient self-administration. After removal of an adhesive liner from the bottom of the device, it is placed onto the body. An on-body interlock mechanism prevents accidental initiation of dose delivery from occurring before the operator is ready. After pushing the button when the patient is ready to start the injection, a soft indwelling cannula is automatically inserted into the subcutaneous layer to administer the dose with minimal pain or irritation. The device is then programmed to automatically deliver the dose at the speed and duration designated by the pharmaceutical customer.

An electronic user interface conveys key information to the patient, with tones and colors indicating the status of the device during each stage of dose delivery. Furthermore, no sharp is exposed during any stage during usage of the device, to virtually eliminate the risk of needlestick injury to the patient or those downstream following its compact, convenient disposal.

Many of the pharmaceutical companies now working with Unilife are attracted to the modular, flexible nature of its family of bolus injectors. Most of these companies require access to a technology platform from which they can customize each device to the specific needs of a series of pipeline molecules and target patient populations.

In recognition of the fact that every molecule is different, Unilife can customize every device across a number of was to simplify the process of getting the drug into the primary container. Accordingly, Unilife’s range of bolus internal areas, including dose volume, drug viscosity, and injection delivery duration.

Unilife’s Precision-TherapyTM range of bolus injectors are designed for use with bolus-based therapies that require short or long duration injections. The Flex-TherapyTM range of bolus injectors are designed for use with rate-based therapies that require subcutaneous infusion over a longer duration of time in which the delivery rate is controlled for hours or days.

Unilife’s philosophy is not to force pharmaceutical companies into the use of one particular material or supplier for components, such as glass or elastomers. It has developed an open architecture model for materials management whereby it works in parallel with the customer to select preferred component materials from a network of established, validated suppliers. With Unilife able to configure every device around the material management preferences of a customer, it is a provider of an integrated delivery system rather than just rigid commodity components.


Unilife’s bolus injectors are now ready for evaluation by pharmaceutical companies for prospective use in human clinical trials for large-dose volume injectable therapies. Unilife is already working with a number of pharmaceutical and biotechnology companies to customize each device to address the specific needs of a series of pipeline and approved molecules.

Following head-to-head user acceptance and preference studies conducted by some pharmaceutical customers, Unilife has been advised its bolus injectors have been selected to enter the next phase of evaluations for use with a number of pipeline drugs. Upon successful completion of these evaluations, Unilife expects its products will be considered by pharmaceutical customers for the target launch of a number of biologic therapies.

Mr. Alan Shortall is the Founder, CEO, and Executive Director of Unilife Corporation, a US-based developer and commercial supplier of injectable drug delivery systems. Established in 2002, it builds long-term collaborations with pharmaceutical and biotechnology companies seeking to utilize its innovative and highly differentiated devices to enable or enhance the clinical development, regulatory approval, and lifecycle management of their injectable therapies. Mr. Shortall has guided the development by Unilife of one of the most expansive and marketdriven portfolios of primary drug containers and advanced delivery systems available for the administration of injectable therapies. Device platforms include prefilled syringes with integrated needle retraction, auto-injectors, drug reconstitution delivery systems, bolus injectors, and other specialized delivery systems. For more information, visit