Electromotive administration of a new morphine formulation: morphine citrate

Electromotive Enhanced Drug Administration in Oncology: Principles, Evidence, Current and Emerging Applications

Local-regional administration of cytotoxic drugs is an important adjunct to systemic chemotherapy amongst cancer patients. It allows for targeted delivery of agents at high concentration to target sites while minimizing systemic side effects. Despite the pharmacokinetic advantages of the local-regional approach, drug transport into tumor nodules remains limited due to the biophysical properties of these tissues. Electromotive enhanced drug administration (EMDA) represents a potential solution to overcome challenges in local drug transport by applying electric currents. Through electrokinetic phenomena of electromigration, electroosmosis and electroporation, electric currents have been shown to improve drug penetration and distribution in a wide variety of clinical applications. Amongst patients with non-muscular invasive bladder cancer (NMIBC) and basal and squamous cell skin cancers, EMDA has been successfully adopted and proven efficacious in several pre-clinical and clinical studies. Its application in ophthalmological and other conditions has also been explored. This review provides an overview of the underlying principles and factors that govern EMDA and discusses its application in cancer patients. We also discuss novel EMDA approaches in pre-clinical studies and explore future opportunities of developments in this field.

Acute postoperative pain management: focus on iontophoretic transdermal fentanyl

Despite progress in the management of chronic pain, acute pain remains an issue for many postoperative patients. Although patient-controlled analgesia (PCA) has demonstrated efficacy and patient satisfaction, current techniques using intravenous (IV) administration present limitations, including the risk of programming errors and the potential to limit patient mobility due to pumps, lines, and tubing. The patient-controlled fentanyl hydrochloride (HCl) iontophoretic transdermal system (fentanyl ITS) was designed to address these concerns. Fentanyl ITS is an innovative, needle-free, self-contained drug-delivery system that uses iontophoretic technology to deliver fentanyl through the skin by application of a low-intensity electrical field. The results of several clinical studies are presented in this review. In three phase 3 placebo-controlled trials, fentanyl ITS was shown to be superior to placebo for the treatment of postoperative pain following major abdominal, orthopedic, and thoracic surgery. The results of one active-comparator phase 3 trial demonstrated comparable safety and efficacy with a standard morphine IV PCA dosing regimen, without significant difference in the side effect profile. Fentanyl ITS represents a safe, easy to use, non-invasive, and convenient alternative to current acute postoperative pain management modalities.

Fentanyl HCl iontophoretic transdermal system (ITS): clinical application of iontophoretic technology in the management of acute postoperative pain

The fentanyl HCl iontophoretic transdermal system (fentanyl ITS) is a novel patient-controlled analgesia (PCA) system that has been approved in the USA and Europe for the management of acute, moderate-to-severe postoperative pain. This system extends the applicability of transdermal drug delivery to acute pain management, allowing patients to self-administer pre-programmed doses of fentanyl non-invasively through the use of iontophoretic technology. Iontophoresis is the process by which an electric current is used to drive ionized drug molecules across the skin and into the systemic circulation. Results of a recent US clinical trial found the fentanyl ITS to provide pain control equivalent to a standard regimen of morphine i.v. PCA, with a similar incidence of opioid-related adverse events. The fentanyl ITS may offer a number of clinical advantages over existing PCA modalities. Its method of drug delivery avoids the risk of complications from needle-related injuries and infection, and its pre-programmed electronics eliminate the potential for manual programming errors and excessive dosing. In addition, the compact size of the system could enable greater patient mobility following surgery. The fentanyl ITS has the potential to become a valuable option in the management of acute postoperative pain.

Iontophoretic drug delivery

The composition and architecture of the stratum corneum render it a formidable barrier to the topical and transdermal administration of therapeutic agents. The physicochemical constraints severely limit the number of molecules that can be considered as realistic candidates for transdermal delivery. Iontophoresis provides a mechanism to enhance the penetration of hydrophilic and charged molecules across the skin. The principal distinguishing feature is the control afforded by iontophoresis and the ability to individualize therapies. This may become significant as the impact of interindividual variations in protein expression and the effect on drug metabolism and drug efficacy is better understood. In this review we describe the underlying mechanisms that drive iontophoresis and we discuss the impact of key experimental parameters-namely, drug concentration, applied current and pH-on iontophoretic delivery efficiency. We present a comprehensive and critical review of the different therapeutic classes and molecules that have been investigated as potential candidates for iontophoretic delivery. The iontophoretic delivery of peptides and proteins is also discussed. In the final section, we describe the development of the first pre-filled, pre-programmed iontophoretic device, which is scheduled to be commercialized during the course of 2004.

Electromotive drug administration of lidocaine to anesthetize the bladder before botulinum-A toxin injections into the detrusor

STUDY DESIGN

Prospective, open label, cross-over-designed clinical study.

OBJECTIVE

To evaluate the effectiveness of an instillation of lidocaine into the bladder with versus without electromotive drug administration (EMDA) to anesthetize the bladder before botulinum-A toxin injections.

SETTING

Neurourology, Swiss Paraplegic Center, Balgrist University Hospital, Zurich, Switzerland.

METHODS

In all, 28 patients with severe neurogenic detrusor overactivity but preserved bladder sensibility were treated with botulinum-A toxin injections into the detrusor muscle. A measure of 300 u of botulinum-A toxin (Botox) was injected at 30 sites sparing the trigone. Prior to the injection, the bladder was anesthesized with conventional lidocaine instillation in a group of 10 patients and with lidocaine instillation enhanced by EMDA in 28 patients. The patients scored the injection pain on a 10-point rating scale. Pain rating scores with versus without EMDA enhancement of the lidocaine instillation were analyzed and the costs of the EMDA procedure were compared to general/spinal anesthesia.

RESULTS

The mean pain score of the 10 patients who underwent the injections of Botox after conventional lidocaine instillation was 4.0 (SD 1.6). Following EMDA enhanced lidocaine instillation slight even or no pain occurred during the injections of Botox, and the mean pain score was 0.5 (SD 0.2). Compared to spinal or general anesthesia, the local anesthesia saved around 15% of the costs.

CONCLUSIONS

EMDA enhanced instillation of lidocaine enables a sufficient anesthesia of the bladder wall that ensures a painless application of the botulinum-A toxin injections into the detrusor muscle. This method may avoid general or spinal anesthesia in patients with preserved bladder sensibility. It ensures considerable cost reduction, avoids anesthesia-related risks and complications and enables the procedure on an outpatient basis.

Clinical pharmacokinetics of transdermal opioids: focus on transdermal fentanyl

Transdermal delivery allows continuous systemic application of opioids through the intact skin. This review analyses the pharmacokinetic properties of transdermal opioid administration in the context of clinical experience, with a focus on fentanyl. A transdermal therapeutic system (TTS) for fentanyl has been developed. The amount of fentanyl released is proportional to the surface area of the TTS, which is available in different sizes. After the first application of a TTS, a fentanyl depot concentrates in the upper skin layers and it takes several hours until clinical effects are observed. The time from application to minimal effective and maximum serum concentrations is 1.2 to 40 hours and 12 to 48 hours, respectively. Steady state is reached on the third day, and can be maintained as long as patches are renewed. Within each 72-hour period, serum concentrations decrease gradually over the second and third days. When a TTS is removed, fentanyl continues to be absorbed into the systemic circulation from the cutaneous depot. The terminal half-life for TTS fentanyl is approximately 13 to 25 hours. The interindividual variability of serum concentrations, partly caused by different clearance rates, is markedly larger than the intraindividual variability. The effectiveness of TTS fentanyl was first demonstrated in acute postoperative pain. However, the slow pharmacokinetics and large variability of TTS fentanyl, together with the relatively short duration of postoperative pain, precluded adequate dose finding and led to inadequate pain relief or, especially, a high incidence of respiratory depression; such use is now contraindicated. Conversely, in cancer pain, TTS fentanyl offers an interesting alternative to oral morphine, and its effectiveness and tolerability in this indication has been demonstrated by a number of trials. Its usefulness in chronic pain of nonmalignant origin remains to be confirmed in controlled trials. In general, TTS fentanyl produces the same adverse effects as other opioids, mainly sedation, nausea, vomiting and constipation. In comparison with oral morphine, TTS fentanyl causes fewer gastrointestinal adverse events. The risk of hypoventilation is comparatively low in cancer patients. Sufentanil and buprenorphine may also be suitable for transdermal delivery, but clinical results are not yet available. Transdermal morphine is only useful if applied to de-epithelialised skin. However, iontophoresis may allow transdermal administration of opioids, including morphine, with a rapid achievement of steady state concentrations and the ability to adjust delivery rates. This would be beneficial for acute and/or breakthrough pain, and initial clinical trials are in progress.

Electromotive drug administration of lidocaine to anesthetize the bladder before intravesical capsaicin

PURPOSE

The discomfort caused by intravesical capsaicin during instillation may restrict its use in some patients. We studied the effectiveness of using electromotive drug administration (EMDA) of lidocaine to anesthetize the bladder before capsaicin.

MATERIALS AND METHODS

EMDA of lidocaine and epinephrine was performed in 8 patients with detrusor hyperreflexia using catheters, electrodes and an electrical current generator (20 mA., 15 minutes) followed immediately by intravesical capsaicin (2 mmol./l.) for 30 minutes under urodynamic monitoring. The patients scored suprapubic pain at 5 minutes and at the end of the capsaicin instillations on a scale of 0 to 10. Of the 8 patients 5 had had previous capsaicin treatments and the scores were compared to previous scores when intravesical lidocaine without EMDA had been used as local anesthesia before capsaicin.

RESULTS

The pain scores during capsaicin instillations after EMDA of lidocaine were much lower than those during capsaicin instillations after lidocaine alone. EMDA virtually eliminated the hyperreflexic contractions of the bladder occurring during capsaicin instillations, thus reducing the risk of urethral leakage, and prevented autonomic dysreflexia that had previously occurred in 1 patient.

CONCLUSIONS

EMDA of lidocaine is an effective means of reducing pain during subsequent intravesical capsaicin, which makes the use of capsaicin in the treatment of detrusor hyperreflexia more acceptable.

Electromotive administration of oxybutynin into the human bladder wall

PURPOSE

To compare concentrations of oxybutynin in the human bladder wall after either passive delivery (PD) or electromotive administration (EMDA).

MATERIALS AND METHODS

Tissue sections of human bladder were inserted into a diffusion cell with urothelium exposed to the donor compartment containing oxybutynin (4.5 mg. in 100 ml. NaCl 0.45%) and an anode. Twelve paired experiments, "current 5 mA/no current", were conducted over 15 minutes. Oxybutynin tissue contents were measured and tissue viability, morphology and oxybutynin stability were assessed.

RESULTS

Mean oxybutynin tissue concentrations were 3.84 micrograms./gm. in samples exposed to EMDA and 0.87 microgram./gm. in samples exposed to PD (p = 0.0006). The mean coefficients of variation were 57.85% in EMDA experiments and 89.78% in PD experiments. Tissues were viable and undamaged histologically and no oxybutynin structural modification was observed.

CONCLUSIONS

EMDA enhances oxybutynin administration into viable bladder wall and reduces the variability in drug delivery rate.

Electromotive drug administration of lidocaine and dexamethasone followed by cystodistension in women with interstitial cystitis

Electromotive drug administration (EMDA) involves the active transport of ionized drugs such as lidocaine by the application of an electric current. Twenty-one female subjects with interstitial cystitis were treated with EMDA of lidocaine and dexamethasone, followed by cystodistension. The procedure was convenient and well tolerated, with hospital attendance for 1 hour. Bladder anesthesia was excellent, with cystodistension from a discomfort level of 200 ml to a mean volume of 600 ml. Eighty-five percent had a good response (reduction in frequency and in pain score by 3 or more) at 2 weeks, with 63% still responding at 2 months. An excellent response (pain score of 0) was present in 25% of patients reviewed at 6 months. These results are comparable to the response following cystodistension under general anesthesia. There is a need for a randomized blinded comparison of lidocaine with and without EMDA. If proven to be of pharmacological efficacy, EMDA would have many applications in facilitating procedures previously requiring general anesthesia.