Current status and future prospects of needle-free liquid jet injectors

Optimal voice coil actuators for needle-free jet injection

We present a scaling model for electrically-actuated needle free jet injectors, establishing the relationship between injection volume and motor size. Using an analytical electromagnetic model for the motor, we derive an optimal motor design, and show that this design is approximately scale-invariant. To illustrate the utility of this model, we then describe the design of a motor for use with 300 μL disposable injection ampoules with a mass of just 300 g, including a light-weight support structure. Experimental verification of the motor performance shows close agreement to model predictions, with a peak force of 1000 N/kg and a 150 m/s water jet delivered.

Needle-free jet injection of rapid-acting insulin improves early postprandial glucose control in patients with diabetes

OBJECTIVE

Clamp studies have shown that the absorption and action of rapid-acting insulin are faster with injection by a jet injector than with administration by conventional pen. To determine whether these pharmacokinetic changes also exist in patients with diabetes and benefit postprandial glucose control, we compared the pharmacologic profiles of insulin administration by jet injection versus conventional insulin pen after a standardized meal in patients with type 1 or type 2 diabetes.

RESEARCH DESIGN AND METHODS

In a randomized, double-blind, double-dummy crossover study, 12 patients with type 1 diabetes and 12 patients with type 2 diabetes received insulin aspart either by jet injection or by conventional pen, in both cases followed by a standardized meal. Blood was sampled for 6 h for determination of glucose and insulin levels to calculate pharmacologic profiles.

RESULTS

Insulin administration by jet injection resulted in shorter time until peak plasma insulin level (51.3 ± 6.4 vs. 91.9 ± 10.2 min; P = 0.003) and reduced hyperglycemic burden during the first hour (154.3 ± 20.8 vs. 196.3 ± 18.4 mmol · min · L(-1); P = 0.041) compared with conventional administration. Jet injection did not, however, significantly reduce the hyperglycemic burden during the 5-h period thereafter. There was no indication that the jet injector performed differently in patients with type 1 and type 2 diabetes.

CONCLUSIONS

The considerably more rapid insulin absorption after administration by jet injector translated to a significant if modest decrease in postprandial hyperglycemia in patients with type 1 and type 2 diabetes. The improved early postprandial glucose control may specifically benefit patients who have difficulty in limiting postprandial glucose excursions.

Engineering approaches to transdermal drug delivery: a tribute to contributions of prof. Robert Langer

Transdermal drug delivery continues to provide an advantageous route of drug administration over injections. While the number of drugs delivered by passive transdermal patches has increased over the years, no macromolecule is currently delivered by the transdermal route. Substantial research efforts have been dedicated by a large number of researchers representing varied disciplines including biology, chemistry, pharmaceutics and engineering to understand, model and overcome the skin's barrier properties. This article focuses on engineering contributions to the field of transdermal drug delivery. The article pays tribute to Prof. Robert Langer, who pioneered the engineering approach towards transdermal drug delivery. Over a period spanning nearly 25 years since his first publication in the field of transdermal drug delivery, Bob Langer has deeply impacted the field by quantitative analysis and innovative engineering. At the same time, he has inspired several generations of engineers by collaborations and mentorship. His scientific insights, innovative technologies, translational efforts and dedicated mentorship have transformed the field.

Polymer nanomicelles for efficient mucus delivery and antigen-specific high mucosal immunity

Micelles for mucosal immunity: A mucosal vaccine system based on γ-PGA nanomicelles and viral antigens was synthesized. The intranasal administration of the vaccine system induces a high immune response both in the humoral and cellular immunity (see picture).

Needle-free injection into skin and soft matter with highly focused microjets

The development of needle-free drug injection systems is of great importance to global healthcare. However, in spite of its great potential and research history over many decades, these systems are not commonly used. One of the main problems is that existing methods use diffusive jets, which result in scattered penetration and severe deceleration of the jets, causing frequent pain and insufficient penetration. Another long-standing challenge is the development of accurate small volume injections. In this paper we employ a novel method of needle-free drug injection, using highly-focused high speed microjets, which aims to solve these challenges. We experimentally demonstrate that these unique jets are able to penetrate human skin: the focused nature of these microjets creates an injection spot smaller than a mosquito's proboscis and guarantees a high percentage of the liquid being injected. The liquid substances can be delivered to a much larger depth than conventional methods, and create a well-controlled dispersion pattern. Thanks to the excellent controllability of the microjet, small volume injections become feasible. Furthermore, the penetration dynamics is studied through experiments performed on gelatin mixtures (human soft tissue equivalent) and human skin, agreeing well with a viscous stress model which we develop. This model predicts the depth of the penetration into both human skin and soft tissue. The results presented here take needle-free injections a step closer to widespread use.

Enhanced absorption of insulin aspart as the result of a dispersed injection strategy tested in a randomized trial in type 1 diabetic patients

OBJECTIVE

We investigated the impact of two different injection strategies on the pharmacokinetics and pharmacodynamics of insulin aspart in vivo in an open-label, two-period crossover study and verified changes in the surface-to-volume ratio ex vivo.

RESEARCH DESIGN AND METHODS

Before the clinical trial, insulin aspart was injected ex vivo into explanted human abdominal skin flaps. The surface-to-volume ratio of the subcutaneous insulin depot was assessed by microfocus computed tomography that compared 1 bolus of 18 IU with 9 dispersed boluses of 2 IU. These two injection strategies were then tested in vivo, in 12 C-peptide-negative type 1 diabetic patients in a euglycemic glucose clamp (glucose target 5.5 ± 1.1 mmol/L) for 8 h after the first insulin administration.

RESULTS

The ex vivo experiment showed a 1.8-fold higher mean surface-to-volume ratio for the dispersed injection strategy. The maximum glucose infusion rates (GIR) were similar for the two strategies (10 ± 4 vs. 9 ± 4; P = 0.5); however, times to reach maximum GIR and 50% and 10% of the maximum GIR were significantly reduced by using the 9 × 2 IU strategy (68 ± 33 vs. 127 ± 93 min; P = 0.01; 38 ± 9 vs. 49 ± 16 min; P < 0.01; 23 ± 6 vs. 30 ± 10 min; P < 0.05). For 9 × 2 IU, the area under the GIR curve was greater during the first 60 min (219 ± 89 vs. 137 ± 75; P < 0.01) and halved until maximum GIR (242 ± 183 vs. 501 ± 396; P < 0.01); however, it was similar across the whole study period (1,361 ± 469 vs. 1,565 ± 527; P = 0.08).

CONCLUSIONS

A dispersed insulin injection strategy enhanced the effect of a fast-acting insulin analog. The increased surface-to-volume ratio of the subcutaneous insulin depot can facilitate insulin absorption into the vascular system.

Devices for overcoming biological barriers: the use of physical forces to disrupt the barriers

Overcoming biological barriers including skin, mucosal membranes, blood brain barrier as well as cell and nuclear membrane constitutes a key hurdle in the field of drug delivery. While these barriers serve the natural protective function in the body, they limit delivery of drugs into the body. A variety of methods have been developed to overcome these barriers including formulations, targeting peptides and device-based technologies. This review focuses on the use of physical methods including acoustic devices, electric devices, high-pressure devices, microneedles and optical devices for disrupting various barriers in the body including skin and other membranes. A summary of the working principles of these devices and their ability to enhance drug delivery is presented.

Body mass index and the efficacy of needle-free jet injection for the administration of rapid-acting insulin analogs, a post hoc analysis

We recently showed in a euglycaemic glucose clamp study among 18 healthy volunteers that using jet injectors rather than conventional pens significantly improved the time-action profiles of rapid-acting insulin analogs. Here, we investigated whether such profiles were modified by body mass index (BMI) and related weight parameters by comparing insulin administration by jet injection to that by conventional pen in subgroups defined by BMI, waist-to-hip ratio, waist circumference and insulin dose. After conventional administration, times to peak insulin levels (T-INS(max)) occurred 31.1 [95% confidence interval (CI) 13.7-48.5] min later and time to maximum glucose requirement (T-GIR(max)) 56.9 (95%CI 26.6-87.3) min later in more obese (BMI > 23.6 kg/m(2)) than in lean subjects (BMI < 23.6 kg/m(2)). In contrast, T-INS(max) and T-GIR(max) were similar in subjects with high and low BMI, when insulin was administered by jet injection. We conclude that using jet injection for insulin administration may especially benefit subjects with higher body weight.

Experimental analysis of the performance of an air-powered needle-free liquid jet injector

An experimental study was performed using a custom-built air-powered needle-free injector to investigate the various injector parameters governing the dynamics of jet injection. A parametric study using five different nozzle sizes at driver pressure ranging from 4 to 8 bar was carried out. The fluid stagnation pressure of the liquid jet was determined using a Honeywell force sensor. Performance plots as a function of various parameters were constructed. It was determined that as the driver pressure increased both the peak and average stagnation pressure increased almost linearly within the operating range considered. Varying the injection nozzle diameter, whilst keeping the driver pressure constant did not have any significant impact on the peak or average stagnation pressure. The chamber length was also varied and no significant influence was found on peak or average stagnation pressure.

Er:YAG laser pulse for small-dose splashback-free microjet transdermal drug delivery

The microjet injector system accelerates drugs and delivers them without a needle, which is shown to overcome the weaknesses of existing jet injectors. A significant increase in the delivered dose of drugs is reported with multiple pulses of laser beam at lower laser energy than was previously used in a Nd:YAG system. The new injection scheme uses the beam wavelength best absorbable by water at a longer pulse mode for elongated microjet penetration into a skin target. A 2.9 μm Er:YAG laser at 250 μs pulse duration is used for fluorescent staining of guinea pig skin and for injection controllability study. Hydrodynamic theory confirms the nozzle exit jet velocity obtained by the present microjet system.

Nanopatch targeted delivery of both antigen and adjuvant to skin synergistically drives enhanced antibody responses

Many vaccines make use of an adjuvant to achieve stronger immune responses. Alternatively, potent immune responses have also been generated by replacing the standard needle and syringe (which places vaccine into muscle) with devices that deliver vaccine antigen to the skin's abundant immune cell population. However it is not known if the co-delivery of antigen plus adjuvant directly to thousands of skin immune cells generates a synergistic improvement of immune responses. In this paper, we investigate this idea, by testing if Nanopatch delivery of vaccine - both the antigen and the adjuvant - enhances immunogenicity, compared to intramuscular injection. As a test-case, we selected a commercial influenza vaccine as the antigen (Fluvax 2008®) and the saponin Quil-A as the adjuvant. We found, after vaccinating mice, that anti-influenza IgG antibody and haemagglutinin inhibition assay titre response induced by the Nanopatch (with delivered dose of 6.5ng of vaccine and 1.4μg of Quil-A) were equivalent to that of the conventional intramuscular injection using needle and syringe (6000ng of vaccine injected without adjuvant). Furthermore, a similar level of antigen dose sparing (up to 900 fold) - with equivalent haemagglutinin inhibition assay titre responses - was also achieved by delivering both antigen and adjuvant (1.4μg of Quil-A) to skin (using Nanopatches) instead of muscle (intramuscular injection). Collectively, the unprecedented 900 fold antigen dose sparing demonstrates the synergistic improvement to vaccines by co-delivery of both antigen and adjuvant directly to skin immune cells. Successfully extending these findings to humans with a practical delivery device - like the Nanopatch - could have a huge impact on improving vaccines.

Needle-free jet injection using real-time controlled linear Lorentz-force actuators

Needle-free drug delivery by jet injection is achieved by ejecting a liquid drug through a narrow orifice at high pressure, thereby creating a fine high-speed fluid jet that can readily penetrate skin and tissue. Until very recently, all jet injectors utilized force- and pressure-generating principles that progress injection in an uncontrolled manner with limited ability to regulate delivery volume and injection depth. In order to address these shortcomings, we have developed a controllable jet injection device, based on a custom high-stroke linear Lorentz-force motor that is feed-back controlled during the time-course of an injection. Using this device, we are able to monitor and modulate continuously the speed of the drug jet, and regulate precisely the volume of drug delivered during the injection process. We demonstrate our ability to control injection depth (up to 16mm) and repeatably and precisely inject volumes of up to 250μL into transparent gels and post-mortem animal tissue.

High-speed jetting and spray formation from bubble collapse

A method to create impacting jets at the micrometer length scale by means of a collapsing cavitation bubble is presented. A focused shock wave from a lithotripter leads to the nucleation of a cavitation bubble below a hole of 25 μm diameter etched in a silicon plate. The plate is placed at an air-water interface. The expansion and collapse of the bubble leads to two separate jets--an initial slow jet of velocity ∼10 m/s and a later faster jet of velocity ∼50 m/s. The jets subsequently impact coaxially, resulting in a circular sheet of liquid in the plane perpendicular to their axis. The sheet is characterized by a ring of droplets at its rim and breaks up into a spray as the shock pressure is increased. The results demonstrate an approach to create a high-speed jet and fine spray on demand at the micrometer scale.

A computational model of a controllable needle-free jet injector

We present a mathematical model of the dynamics of a previously developed needle-free jet injector (NFJI) that is based upon a servo-controlled Lorentz-force motor. The injector creates a fluid jet that can pierce through the skin and deliver a drug to dermal, subcutaneous and muscular tissue. We use the model to predict the jet speed achieved during an injection. The model simulates the electrical response of the motor coil, the mechanical response of the drug piston and ampoule and the friction incident upon the piston during the time course of the injection. High-speed video measurements of piston movement in response to a step input show that the model predicts piston-tip position during an injection within an RMS error of 287 µm. The corresponding jet speed is predicted to be 180 m·s(-1) with a maximum overshoot to 205 m·s(-1).

Randomized controlled study of fractional doses of inactivated poliovirus vaccine administered intradermally with a needle in the Philippines

OBJECTIVE

Comparison of a fractional inactivated poliovirus vaccine (IPV) dose administered intradermally (ID) to a full dose administered intramuscularly (IM).

METHODS

Healthy Filipino infants were randomized to receive IPV as either a fractional (1/5(th)) dose ID by needle injection or a full dose IM at 6, 10, and 14 weeks and a booster at 15-18 months of age. Pre- and post-vaccination anti-polio 1, 2, and 3 titers were estimated. Adverse events were monitored throughout the study.

RESULTS

Following primary series vaccination, anti-polio 1, 2, and 3 titers were ≥8 (1/dil) in 99-100% of participants, and the ID route was non-inferior to the IM route. Depending on the study group, antibody persistence was detected in 83-100% of participants, and the booster dose resulted in a strong anamnestic response in all groups. The incidence of adverse events in each group was similar, except for injection-site erythema (higher in the ID group).

CONCLUSIONS

Primary series and booster vaccination of a fractional IPV dose administered by the ID route was highly immunogenic and well tolerated. These data confirm the medical validity of using fractional ID doses of IPV. The programmatic feasibility of implementing affordable mass vaccination programs based on this delivery mode has yet to be established.

Improved pharmacokinetic and pharmacodynamic profile of rapid-acting insulin using needle-free jet injection technology

OBJECTIVE

Insulin administered by jet injectors is dispensed over a larger subcutaneous area than insulin injected with a syringe, which may facilitate a more rapid absorption. This study compared the pharmacologic profile of administration of insulin aspart by jet injection to that by conventional insulin pen.

RESEARCH DESIGN AND METHODS

Euglycemic glucose clamp tests were performed in 18 healthy volunteers after subcutaneous administration of 0.2 units/kg body wt of aspart, either administered by jet injection or by conventional pen, using a randomized, double-blind, double-dummy, cross over study design. Pharmacodynamic and pharmacokinetic profiles were derived from the glucose infusion rate (GIR) needed to maintain euglycemia and from plasma insulin levels, respectively.

RESULTS

The time to maximal GIR was significantly shorter when insulin was injected with the jet injector compared with conventional pen administration (51 ± 3 vs. 105 ± 11 min, P < 0.0001). The time to peak insulin concentration was similarly reduced (31 ± 3 vs. 64 ± 6 min, P < 0.0001) and peak insulin concentrations were increased (108 ± 13 vs. 79 ± 7 mU/L, P = 0.01) when insulin was injected by jet injection compared with conventional pen injection. Jet injector insulin administration reduced the time to 50% glucose disposal by ∼40 min (P < 0.0001). There were no differences in maximal GIR, total insulin absorption, or total insulin action between the two devices.

CONCLUSIONS

Administration of insulin aspart by jet injection enhances insulin absorption and reduces the duration of glucose-lowering action. This profile resembles more closely the pattern of endogenous insulin secretion and may help to achieve better meal insulin coverage and correction of postprandial glucose excursions.

Clinical results of skin remodeling using a novel pneumatic technology

BACKGROUND

A myriad of technologies are available for the treatment of aging skin. These, however, still lack the ability to combine immediate, short-term and long-term aesthetic results with no downtime. Furthermore, the treatment of fine wrinkles on large surfaces remains challenging, as does the treatment of delicate regions, such as the dorsal hand, neck, and chest.

OBJECTIVES

The aims of this study were to evaluate the short-term as well as the long-term efficacy and safety of a new skin remodeling device that pneumatically accelerates a jet of hyaluronic acid (HA) solution under high pressure into the dermis.

METHODS

Thirty-four participants at three clinical sites underwent treatments with the Airgent device on the face, neck, chest, and dorsal hands for a total of 69 sites. Safety and efficacy were evaluated in short-term (1-3 months) and long-term follow-up (up to 18 months) by photography, by an independent reviewer and by participant self-evaluation. Histology was assessed before and 4 months after the third treatment.

RESULTS

A total of 69 treatment areas were evaluable at 1-3 months follow-up. Photographic analysis demonstrated improvement in skin variables at all body sites treated. Treatment of the face and neck reduced the mean Fitzpatrick-Goldman Wrinkle Classification score by 39.4 and 30.4%, respectively, representing a full wrinkle class improvement. Treatments of the chest demonstrated significant visual improvement. Treatment of the dorsal hands produced good overall improvement (OI), with good improvement of protruding veins. Overall improvement increased with increasing number of treatments. A total of 56 treatment areas were evaluable for long-term follow-up. Treatment of the face and neck reduced the mean Fitzpatrick-Goldman Wrinkle Classification score by 27.6 and 21.2%, respectively. Improvement after treatment of the face represented a full wrinkle class reduction. Treatment of the chest and dorsal hands yielded significant visual improvement. Overall, 80% of subjects were satisfied with the treatment outcome and would recommend the treatment to friends and family. Histological analysis demonstrated increased dermal collagen ΙΙΙ.

CONCLUSIONS

Pneumatic injection of HA under high pressure provides a safe, well-tolerated and effective method for improving the appearance of wrinkles on the face, neck, chest, and dorsal hands. Improvement can be seen as early as 1 month and as long as 18 months after treatment.

Developments in administration of growth hormone treatment: focus on Norditropin® Flexpro®

Recombinant human growth hormone is used for the treatment of growth failure in children and metabolic dysfunction in adults with growth hormone deficiency. However, conventional growth hormone therapy requires daily subcutaneous injections that may affect treatment adherence, and subsequently efficacy outcomes. To enhance potential treatment adherence, improved ease of use of growth hormone delivery devices and long-acting growth hormone formulations are now being developed. Flexpro(®), approved by the US Food and Drug Administration in March 2010, is the most recent pen device developed by Novo Nordisk A/S to deliver Norditropin(®). It is a multidose, premixed, preloaded, disposable pen device that requires relatively less force to inject and does not require refrigeration after initial use. Dose adjustments can be optimized by small dose increments of the pen delivery device at 0.025 mg, 0.05 mg and 0.1 mg. In addition, for patients with needle anxiety, NovoFine(®) needles, some of the shortest and thinnest available, and Autocover(®), which hides the needle during injections, can be used with the Flexpro pen device. This article reviews the Norditropin Flexpro pen device in the context of other growth hormone delivery devices, sustained-release growth hormone formulations in development, and future prospects.

Transdermal delivery of proteins

Transdermal delivery of peptides and proteins avoids the disadvantages associated with the invasive parenteral route of administration and other alternative routes such as the pulmonary and nasal routes. Since proteins have a large size and are hydrophilic in nature, they cannot permeate passively across the skin due to the stratum corneum which allows the transport of only small lipophilic drug molecules. Enhancement techniques such as chemical enhancers, iontophoresis, microneedles, electroporation, sonophoresis, thermal ablation, laser ablation, radiofrequency ablation and noninvasive jet injectors aid in the delivery of proteins by overcoming the skin barrier in different ways. In this review, these enhancement techniques that can enable the transdermal delivery of proteins are discussed, including a discussion of mechanisms, sterility requirements, and commercial development of products. Combination of enhancement techniques may result in a synergistic effect allowing increased protein delivery and these are also discussed.

Human growth hormone treatment: synthesis of literature on product delivery systems and administration practices

PURPOSE

To synthesize current literature on recombinant human growth hormone (rhGH) use and to identify areas of research that have received little to no attention in light of administration practice and patient perception/behavior.

DESIGN AND METHODS

Relevant articles for a systematic review were identified through PubMed.

RESULTS

A total of 43 articles were identified: 9 (15.9%) studies on product administration practices and 34 (84.1%) on patient behavior patterns. Patients primarily preferred simple, convenient, and easy-to-use delivery devices. However, literature addressing the effect of convenient product administration practices on treatment outcomes using real-world patient/caregiver data is lacking.

PRACTICE IMPLICATIONS

Better understanding of real-world product administration practices will help nurses identify areas of improvement in patient education and training.

A Phase I safety study of plasmid DNA immunization targeting carcinoembryonic antigen in colorectal cancer patients

A plasmid DNA vaccine, encoding a truncated form of human CEA fused to a T-helper epitope (CEA66 DNA) was delivered three times intradermally at 2 mg or intramuscularly at 8 mg by Biojector® to patients with colorectal cancer. Prior to the first vaccination, all patients received cyclophosphamide (300 mg/m²) intravenously. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was administered subcutaneously with each vaccination. All patients completed the vaccine schedule. There were no grade 3 or 4 adverse events (AE). The most frequently reported AE grades 1 and 2 were injection site reactions, fatigue, headache, arthralgia, chest tightness and myalgia. Vaccination with CEA66 DNA in combination with GM-CSF was well tolerated and no signs of autoimmunity have been detected.

Needle-free influenza vaccination

Vaccination is the cornerstone of influenza control in epidemic and pandemic situations. Influenza vaccines are typically given by intramuscular injection. However, needle-free vaccinations could offer several distinct advantages over intramuscular injections: they are pain-free, easier to distribute, and easier to give to patients, and their use could reduce vaccination costs. Moreover, vaccine delivery via the respiratory tract, alimentary tract, or skin might elicit mucosal immune responses at the site of virus entry and better cellular immunity, thus improving effectiveness. Although various needle-free vaccination methods for influenza have shown preclinical promise, few have progressed to clinical trials-only live attenuated intranasal vaccines have received approval, and only in some countries. Further clinical investigation is needed to help realise the potential of needle-free vaccination for influenza.

A Model on Liquid Penetration Into Soft Material With Application to Needle-Free Jet Injection

A mathematical model has been presented for a high speed liquid jet penetration into soft solid by a needle-free injection system. The model consists of a cylindrical column formed by the initial jet penetration and an expansion sphere due to continuous deposition of the liquid. By solving the equations of energy conservation and volume conservation, the penetration depth and the radius of the expansion sphere can be predicted. As an example, the calculation results were presented for a typical needle-free injection system into which a silicon rubber was injected into. The calculation results were compared with the experimental results.

Improved DNA vaccination by skin-targeted delivery using dry-coated densely-packed microprojection arrays

HSV-2-gD2 DNA vaccine was precisely delivered to immunologically sensitive regions of the skin epithelia using dry-coated microprojection arrays. These arrays delivered a vaccine payload to the epidermis and the upper dermis of mouse skin. Immunomicroscopy results showed that, in 43 ± 5% of microprojection delivery sites, the DNA vaccine was delivered to contact with professional antigen presenting cells in the epidermal layer. Associated with this efficient delivery of the vaccine into the vicinity of the professional antigen presenting cells, we achieved superior antibody responses and statistically equal protection rate against an HSV-2 virus challenge, when compared with the mice immunized with intramuscular injection using needle and syringe, but with less than 1/10th of the delivered antigen.

Co-administration of tacrolimus suppresses pharmacokinetic modulation of multiple subcutaneously administered human interferon-alpha in Beagle dogs

Specific antibody production is an important issue in crossover pharmacokinetic (PK) studies of protein-based formulations. We recently reported that intravenous co-administration of tacrolimus with multiple human interferon-alpha (h-IFN) administrations successfully suppressed the production of anti-h-IFN antibodies in rats. Since crossover PK studies are preferentially carried out using larger animals such as dogs or monkeys that are capable of accepting the same dosage formulations as those for clinical use, we extended our study of co-administration of tacrolimus with multiple h-IFN administrations to beagle dogs in the present study. Beagle dogs were subcutaneously administered 0.5 million IU/kg of h-IFN once a week for 4 weeks. In some experiments, tacrolimus at 0.01 or 0.1 mg/kg was intravenously co-administered at the same time as the h-IFN administration. Co-administration of the lower dose of tacrolimus (0.01 mg/kg) failed to suppress the anti-h-IFN IgG responses, while co-administration of the higher dose (0.1 mg/kg) successfully suppressed these responses. Moreover, co-administration of tacrolimus had little effect on the serum creatinine concentrations, suggesting that multiple administrations of tacrolimus at the concentrations examined did not cause severe renal disorders. Taken together, the present data confirm that co-administration of tacrolimus is a promising way to assess crossover PK studies of human or humanized proteinic formulations in beagle dogs.

Jet-injection of short hairpin RNA-encoding vectors into tumor cells

The use of the RNA interference (RNAi) through the expression of small hairpin RNA (shRNA) is a promising approach for efficient gene silencing for therapeutic applications. In this chapter, we describe the in vivo reversal of the classical MDR1/P-glycoprotein (MDR1/P-gp)-mediated multidrug resistance (MDR) phenotype by shRNA. For local intratumoral delivery of naked shRNA-encoding vector constructs, the nonviral jet-injection was used. This jet-injector system uses compressed air to inject small volumes (5-10 muL) of naked nucleic acid solutions into tumor tissues. Furthermore, the design of the jet-injector allows multiple injections. Under our experimental design, the delivery of plasmid DNA encoding anti-MDR shRNA by jet-injection into human MDR1/P-gp overexpressing MaTu/ADR breast cancer xenografts resulted in a decrease of MDR1 mRNA expression level to more than 90%. Accordingly, the corresponding MDR1/P-gp protein is no longer detectable in the tumors after anti-MDR1 shRNA vector injection. Furthermore, combination of two intratumoral jet-injections of anti-MDR1 shRNA vectors with two intravenous administrations of doxorubicin is sufficient for a complete reversal of the MDR phenotype in association with tumor growth inhibition.

Enhancement of transdermal drug delivery via synergistic action of chemicals

Transdermal drug delivery is an attractive alternative to conventional techniques for administration of systemic therapeutics. One challenge in designing transdermal drug delivery systems is to overcome the natural transport barrier of the skin. Chemicals offer tremendous potential in overcoming the skin barrier to enhance transport of drug molecules. Individual chemicals are however limited in their efficacy in disrupting the skin barrier at low concentrations and usually cause skin irritation at high concentrations. Multicomponent mixtures of chemicals, however, have been shown to provide high skin permeabilization potency as compared to individual chemicals without necessarily causing irritation. Here we review systems employing synergistic mixtures of chemicals that offer superior skin permeation enhancement. These synergistic systems include solvent mixtures, microemulsions, eutectic mixtures, complex self-assembled vesicles and inclusion complexes. Methods for design and discovery of such synergistic systems are also discussed.

Novel jet-injection technology for nonviral intratumoral gene transfer in patients with melanoma and breast cancer

PURPOSE

This phase I clinical trial evaluated safety, feasibility, and efficiency of nonviral intratumoral jet-injection gene transfer in patients with skin metastases from melanoma and breast cancer.

EXPERIMENTAL DESIGN

Seventeen patients were enrolled. The patients received five jet injections with a total dose of 0.05 mg beta-galactosidase (LacZ)-expressing plasmid DNA (pCMVbeta) into a single cutaneous lesion. Clinical and laboratory safety monitoring were done. Systemic plasmid clearance was monitored by quantitative real-time PCR of blood samples throughout the study. All lesions were resected after 2 to 6 days. Intratumoral plasmid DNA load, DNA distribution, and LacZ expression was analyzed by quantitative real-time PCR, quantitative reverse transcription-PCR, Western blot, immunohistochemistry, and 5-bromo-4-chloro-3-indolyl-beta-D-galactoside staining.

RESULTS

Jet injection of plasmid DNA was safely done in all patients. No serious side effects were observed. Thirty minutes after jet injection, peak plasmid DNA levels were detected in the blood followed by rapid decline and clearance. Plasmid DNA and LacZ mRNA and protein expression were detected in all treated lesions. Quantitative analysis revealed a correlation of plasmid DNA load and LacZ-mRNA expression confirmed by Western blot. Immunohistochemistry and 5-bromo-4-chloro-3-indolyl-beta-D-galactoside staining showed LacZ-protein throughout the tumor. Transfected tumor areas were found close and distant to the jet-injection site with varying levels of DNA load and transgene expression.

CONCLUSION

Intratumoral jet injection of plasmid DNA led to efficient LacZ reporter gene expression in all patients. No side effects were experienced, supporting safety and applicability of this novel nonviral approach. A next step with a therapeutic gene product should determine antitumor efficacy of jet-injection gene transfer.

Nonviral jet-injection technology for intratumoral in vivo gene transfer of naked DNA

The main challenges for application of gene therapy to patients are poor selectivity in vector targeting, insufficient gene transfer, and great difficulties in systemic treatment in association with safety concerns for particular vector systems. For success in gene therapy, safe, applicable, and efficient transfer technologies are required. Because of the complex nature of targeted vector delivery to the tumor, our strategy for gene therapy is focused on the development of local nonviral gene transfer. This approach of local interference with tumor growth and progression could contribute to better control of the disease. Transfer of naked DNA is an important alternative to liposomal or viral systems. Different physical procedures are used for improved delivery of naked DNA into the target cells or tissues in vitro and in vivo. Among the various nonviral gene delivery technologies, jet-injection is gaining increased attractiveness, because this technique allows gene transfer into different tissues with deep penetration of naked DNA by circumventing the disadvantages associated with, e.g., viral vectors. The jet-injection technology is based on jets of high velocity for penetration of the skin and underlaying tissues, associated with efficient transfection of the affected area. The jet-injection technology has been successfully applied for in vivo gene transfer in different tumor models. More importantly, the efficacy and safety of jet-injection gene transfer have recently been investigated in a phase I clinical trial.

Micro-scale devices for transdermal drug delivery

Skin makes an excellent site for drug and vaccine delivery due to easy accessibility, immuno-surveillance functions, avoidance of macromolecular degradation in the gastrointestinal tract and possibility of self-administration. However, macromolecular drug delivery across the skin is primarily accomplished using hypodermic needles, which have several disadvantages including accidental needle-sticks, pain and needle phobia. These limitations have led to extensive research and development of alternative methods for drug and vaccine delivery across the skin. This review focuses on the recent trends and developments in this field of micro-scale devices for transdermal macromolecular delivery. These include liquid jet injectors, powder injectors, microneedles and thermal microablation. The historical perspective, mechanisms of action, important design parameters, applications and challenges are discussed for each method.

The hidden cost of skin scars: quality of life after skin scarring

BACKGROUND

Surprisingly little is known about how skin scars affect patients' lives, though specialist clinical impressions suggest their impact is related to both their physical and psychosocial effects. Facial scars have been shown to cause high levels of anxiety and self-consciousness, but further work has been neglected. We aimed to explore the influence of skin scars on patients' quality of life (QoL) and identify potential implications for clinical practice.

METHODS

We adopted a needs-based approach to QoL and conducted semi-structured interviews with scar patients at a specialist clinic. Transcribed data underwent interpretative phenomenological analysis to identify common themes in individuals' personal experiences.

RESULTS

Thirty-four scar patients (24 women; aged 14-70 years, mean=35.7 years, SD=17.9 years) with a wide range of scar type, severity and onset were recruited. Five hundred and seventy-three statements were identified from interview transcripts relating to need impairment by skin scars. These were subsequently classified into 44 themes covering five main areas: physical comfort and functioning; acceptability to self and others; social functioning; confidence in the nature and management of the condition; emotional well-being. The majority of respondents were unhappy with their scar's appearance due to their perceived stigma and psychological associations, and thus adopted different coping behaviours to hide or compensate for them. Often this made them unsociable and interfered with their communication skills, personal relationships, work life and leisure activities. Concerns about the diagnosis and persistent nature of scars were common, whilst unempathic management by general physicians and frustrations of current treatment compounded distress.

CONCLUSIONS

There are five main areas of impact on the needs of scar patients that should be addressed in their management, which are greater and more complex than previously considered. Support services should be made available, along with clinician and public education to improve management and help reduce patient distress. A need for a carefully designed measure of scar-related QoL is also indicated, for use in clinical settings and trials.

Piezoelectric control of needle-free transdermal drug delivery

Transdermal drug delivery occurs primarily through hypodermic needle injections, which cause pain, require a trained administrator, and may contribute to the spread of disease. With the growing number of pharmaceutical therapies requiring transdermal delivery, an effective, safe, and simple needle-free alternative is needed. We present and characterize a needle-free jet injector that employs a piezoelectric actuator to accelerate a micron-scale stream of fluid (40-130 microm diameter) to velocities sufficient for skin penetration and drug delivery (50-160 m/s). Existing jet injectors, powered by compressed springs and gases, are not widely used due to painful injections and poor reliability in skin penetration depth and dose. In contrast, our device offers electronic control of the actuator expansion rate, resulting in direct control of jet velocity and thus the potential for more precise injections. We apply a simple fluid-dynamic model to predict the device response to actuator expansion. Further, we demonstrate that injection parameters including expelled volume, jet pressure, and penetration depth in soft materials vary with actuator expansion rate, but are highly coupled. Finally, we discuss how electronically-controlled jet injectors may enable the decoupling of injection parameters such as penetration depth and dose, improving the reliability of needle-free transdermal drug delivery.

Needle-free vaccine delivery

The need for minimally invasive delivery methods is urgent. As the number of registered vaccines increases, so does the number of injections. The use of sharps can be unsafe and needle immunisation is less suitable for mass immunisations during emergencies such as pandemics or bioterrorist attacks. The approach of combining vaccines has limitations due to high development costs, risk of pharmaceutical or immunological interference and economic risks. Advancements in the development of alternatives to injection with syringes and needles are discussed in this paper, and include: mucosal vaccination, injection without needles and vaccine delivery via the skin.

Does needle size matter?

Hypodermic needles are in widespread use, but patients are unhappy with the pain, anxiety, and difficulty of using them. To increase patient acceptance, smaller needle diameters and lower insertion forces have been shown to reduce the frequency of painful injections. Guided by these observations, fine needles and microneedles have been developed to minimize pain and have found the greatest utility for delivery of vaccines and biopharmaceuticals such as insulin. However, pain reduction must be balanced against limitations of injection depth, volume, and formulations introduced by reduced needle dimensions. In some cases, needle-free delivery methods provide useful alternatives.

Needle-free delivery of lidocaine for reducing the pain associated with the fine-needle aspiration biopsy of thyroid nodules: time-saving and efficacious procedure

OBJECTIVE

Fine-needle aspiration biopsy (FNAB) is a mandatory procedure in evaluation of thyroid nodules. However, it is sometimes perceived as a painful procedure by the patients. Efficacy of the needle-free injection of local anesthesia for reducing the pain associated with other cutaneous procedures that involve needle insertion was previously reported. In this double-blind, placebo-controlled clinical trial, we evaluated the effectiveness of a needle-free injection of lidocaine in achieving satisfactory pain control in patients undergoing FNAB of thyroid nodules.

DESIGN

Patients were allocated to receive either lidocaine administered by needle-free injection system (n = 55) or placebo (isotonic saline) (n = 52) 2-3 minutes before FNAB. A series of four aspirations of each nodule was performed. The patients rated pain associated with the procedure according to a 100-mm visual analog scale (VAS), an 11-point numeric rating scale (NRS), and a four-category verbal rating scale (VRS).

MAIN OUTCOME MEASURE

The two groups studied were similar with respect to age, sex, thyroid volume, nodule size, and nodule site. When the effectiveness of lidocaine was compared with that of placebo, the mean VAS score was 11.4 +/- 13.6 mm versus 38.2 +/- 35.5 mm (p < 0.0001) and the mean NRS score was 1.4 +/- 1.5 points versus 3.9 +/- 2.6 points (p < 0.0001), respectively. The absolute numbers according to VRS score in each group was also significantly different (p < 0.0001). The percentage of patients with "no pain" or "mild pain" in the lidocaine group (90.9%) was significantly higher than that in the placebo group (44.2%) (p < 0.0001). Less than 10% of the patients in lidocaine group experienced moderate pain and none experienced severe pain. No adverse treatment-related effects were observed.

CONCLUSIONS

To our knowledge, this is the first study demonstrating that the needle-free delivery of lidocaine is an effective, useful, and noninvasive method of providing local anesthesia for the FNAB of thyroid nodules.