Administration of antibiotics and therapeutic agents

Abstract

Antibiotics are administered in a surgical site subcutaneously via a small or stab incision in the surgical field. Transcutaneous ultrasonic vibrations are applied across the surgical field, which is then opened in the usual manner, to thereby provide a surgical field which contains a vastly higher and more effective level of antibiotic. At the same time the underlying tissue is hydrated.

Claims

1. A MRSA infection treatment system for treating a MRSA infected tissue of a patient, the MRSA infection treatment system comprising: a solution comprising: saline; and a dose of Vancomycin dissolved in the saline, wherein the Vancomycin is not encapsulated in vesicles, wherein the dose of Vancomycin is sufficient for treatment of the MRSA infected tissue; a blunt cannula configured for subcutaneous injection of the solution with the dose of Vancomycin dissolved in the saline into a treatment field associated with the MRSA infected tissue; and an ultrasound system comprising: a handle; an ultrasonic transducer head operatively coupled with the handle, the ultrasonic transducer head comprising crystals embedded in a polymer, the handle configured to facilitate handling and positioning of the ultrasonic transducer head to contact a surface of a skin tissue; and a power source operatively coupled with the ultrasonic transducer head, the power source and ultrasonic transducer head of the ultrasound system configured to broadcast ultrasound transcutaneously from the ultrasonic transducer head, wherein the ultrasound system is configured to broadcast ultrasound transcutaneously from the ultrasonic transducer head at a power density of 2.5 to 4 W/cm.sup.2 and at a frequency less than 5 MHz for less than 5 minutes toward the treatment field associated with the MRSA infected tissue that has been injected subcutaneously with the solution, wherein the power source and ultrasonic transducer head of the ultrasound system are configured to broadcast ultrasound at the power density of 2.5 to 4 W/cm.sup.2 and at the frequency less than 5 MHz for less than 5 minutes to interact with the subcutaneously injected solution to disperse the subcutaneously injected solution with the dose of Vancomycin dissolved therein through the treatment field and into the MRSA infected tissue via microstreaming or by cavitation; and such that interaction of wherein the broadcasted ultrasound is configured to interact with the subcutaneously injected solution sufficiently disperses the dose of Vancomycin through the MRSA infected tissue at therapeutically effective concentrations for treating the MRSA infected tissue.

2. The MRSA infection treatment system of claim 1, further comprising a solution warmer for prewarming the solution prior to subcutaneous injection.

3. The MRSA infection treatment system of claim 1, wherein the broadcasted ultrasound is configured to interact with the solution to disperse the solution with the dose of Vancomycin dissolved therein down to a deep fascia tissue of the patient.

4. The MRSA infection treatment system of claim 1, further comprising a temperature monitor for monitoring a temperature of the treatment field during treatment of the MRSA infected tissue.

5. The system of claim 1, wherein the dose of Vancomycin is sufficient to achieve at least a minimum inhibitory concentration (MIC) within the treatment field associated with the MRSA infected tissue while remaining below serum concentration levels associated with toxic effects.

6. The system of claim 1, wherein the dose is a fraction of a corresponding standard intravenous dose of Vancomycin for the treatment field.

7. The system of claim 1, wherein the ultrasound system is configured to broadcast ultrasound transcutaneously from the ultrasonic transducer head at a frequency between 0.5 to 5 MHz to facilitate dispersal of the solution throughout the treatment field associated with the MRSA infected tissue in less than 5 minutes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flow chart of the method.

(2) FIG. 2 is a schematic section of a patient showing the first step in the method.

(3) FIG. 3 is a schematic section of a patient showing the second step in the method.

(4) FIG. 4 is a schematic section of a patient showing the third step in the method

(5) FIG. 5 is a schematic section of a patient showing the fourth step in the method.

(6) FIG. 6 is a plot comparing the time dependence of the serum and tissue concentration of a therapeutic agent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) Referring to FIGS. 1 through 6, wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved method for the pre-surgical prophylactic administration of antibiotics and other therapeutic agents, generally denominated 100 herein.

(8) In accordance with the present invention, antibiotics or another therapeutic agents is injected subcutaneously via a small or stab incision using a blunt cannula into the area to be treated. High frequency ultrasound energy is broadcast transcutaneously to disperse the antibiotic or other therapeutic agent into the subcutaneous volume to be exposed in surgery by a process of ultrasonic micro streaming. If the area is to be opened, as in surgery, the addition of fluid together with the antibiotic or other therapeutic agent adds extra hydration to the treated area, thus preventing dehydration from exposure during surgery.

(9) Accordingly, the process is carried out by first defining a surgical or treatment field and the incision line or region 201 thereof. In the first step 110 in the process 100, as described in the Flow chart of FIG. 1, the incision line 201 is a reference line, typically drawn on the patient's skin 216 that defines the entire length of the eventual surgical incision. However, as will be more fully understood in light of the further disclose of the method, the incision line 201 could also represent the region of the body tissue to be exposed during surgery or otherwise most subject to post operative surgical infection.

(10) Referring to FIG. 2, a portion of the patient's body 20 in which a surgical procedure is to be performed is shown in section. In the next step 120 in the process 100, as a short stab wound 205 is made at the end of the intended surgical incision line 201.

(11) In the next step 130 in the process 100, as shown in FIG. 3, an irrigating cannula 300 comprising a hollow blunt tip 310 is inserted into the short stab wound 205. A solution of fluid containing an antibiotic or related therapeutic agent is delivered through the hollow needle tip 310 of the infusion cannula 300 and is infused into a volume 312 of the tissue underlying the surgical incision line 201, which will eventually be exposed in the surgical procedure. As this incision 205 is small the potential for infection through it, while antibiotics are being delivered, is comparatively small.

(12) The volume 312 of tissue to be infused is determined by the surgical procedure. In general, the volume 312 of infusion should include the area surrounding the portion of the tissue that will be exposed and is subject to infection as well as dehydration. Suitable isotonic solutions for dissolving an antibiotic agent may be used for infusion, for example, saline or ringer's lactate, with the optional addition of epinephrine or xylocaine. The amount of solution may vary depending upon the size of the patient and the area to be infused. Varying degrees of solution infusion are possible while keeping in mind that the infused solution attenuates the ultrasonic energy heating to protect the tissue and provides a greater hydration effect. The fluid is preferably warmed (e.g., with a solution warmer 440) to body temperature and is infused in the subcutaneous tissue.

(13) As shown by the outline of the needle 310 and 310, the cannula 300 is moved externally such that tip of the needle 330 is transport across region 312 dispersing the therapeutic agent therein. Typically the cannula tip 310 is moved under the incision line at a rate commensurate with the fluid injection rate to provide an even and uniform dose of the agent in the surgical area. It should be noted that region 312 is generally at least a substantial portion of the tissue below the intended surgical incision line 201. Thus, the depth of the short or stab wound 205 as well as that of region 312 can be just under the skin 216 or deeper, but is generally about 1 cm or less, depending in part on the location of the organ or anatomy requiring surgery, as well as the potential infusion kinetics of the antibiotic agent in the surrounding tissue, as will be further described.

(14) As illustrated in FIG. 4, in process step 140, after the therapeutic solution is infused in step 130, and removal of the cannula 300 through the first incision 205, the physician externally applies ultrasound through the skin over the incision or treatment line region. The ultrasonic instrument 400 comprises a handle 410 coupled to a power source 430, and an ultrasonic transducer head 420 (protected by a sterile sheath) is used to apply ultrasonic energy though the skin 216 of the patient to the volume 312 of tissue which has received the antibiotic agent. Preferably the ultrasonic transducer in head 420 or elsewhere comprises crystals embedded in a polymer, such as, for example, a lead zirconate titanate crystals embedded in acrylate, that diffuses the energy relatively more superficially than other transducers. A transmitting gel is applied to the skin 216 to provide coupling between the ultrasonic transducer head 420 and the patient's skin 216 for the efficient transmission of the ultrasonic waves. The physician holds the instrument 430 by the handle 431 and applies the transducer head 432 to the patient's skin 216, moving the transducer generally over the intended surgical incision line 201 (as in the direction of arrow 401) but most generally throughout the area of skin corresponding to the volume 412 of tissue beneath the skin 216 to be treated. This volume of tissue 412 (as shown in FIG. 5.) generally extends down to the deep fascia 413.

(15) In one embodiment, the ultrasonic field is introduced into the tissue through the skin at a frequency of 1 MHz and a power density of 3 watts/cm2 for a sufficient time for the tissues to become warm and soft generally about 2-5 minutes. Preferably an ultrasonic frequency of about 0.5 to 5 MHz is used with a power density ranging from about 2.5 to 4 watts/cm2. The application of the ultrasonic energy is believed to cause cavitation and microstreaming, i.e., the movement of the fluid in a linear direction away from the ultrasonic energy source. Preferably, the temperature of the site is monitored (e.g., with a temperature monitor 450) to prevent excess heat buildup. Should the ultrasonic vibration cause too much heat, the surrounding tissue and skin can be inadvertently damaged.

(16) Upon completion of the transcutaneous broadcast of energy in step 140, the surgical procedure commences with the surgical incision 500 opening to access the surgical site as illustrated in FIG. 5 (corresponding to step 150 of process 100 in FIG. 1). The surgical incision 500 is made along incision line 201.

(17) The ultimate surgical procedure is facilitated by the ultrasonic treatment in combination with the infusion of the fluid super-hydrates the tissue, lessening the effects of tissue dehydration from exposure of the fatty and other tissue to air, as well as the prophylactic effect of the antibiotic agent.

(18) Alternative energy sources may be used such as other acoustic waves that heat the tissue with pressure from the sound waves, and electromagnetic radiation, such as e.g. light, collimated light, laser or radio frequency energy that is used in a manner that minimizes cell damage while it disperses the antibiotic agent and fluid subcutaneously

(19) As reported in An Additional Dose of Cefazolin for Intraoperative Prophylaxis Jpn J Surg (1999) 29:1233-1236, by Ohge et al. it is desirable to provide a tissue level of Cefazolin of about 4.mu.Math.g/ml) to achieve a minimum inhibitory concentrations (MIC) for 80% (MIC.sub.80) of four bacterial species. The MICs of Cefazolin were determined for 360 isolates of methicillin-sensitive Staphylococcus aureus (MSSA), 204 isolates of Klebsiella pneumoniae, 314 isolates of Escherichia coli, and 30 isolates of Streptococcus spp. In light of these findings, Ohge et al. then pre-operatively treated patients with an intravenous bolus of 1 g of cefazolin was administered over a period of 3-5 minutes at the time of skin incision. Then, 5 ml of peripheral blood, about 3 g of subcutaneous adipose tissue, and peritoneum samples were obtained intraoperatively during and after the procedure. Ohge then discovered that this protocol resulted in a mean tissue concentration of about 10.mu.Math.g/ml an hour after surgery commenced, but then dropped below 4.mu.Math.g/ml after slightly more than 2 hours of surgery. During the same time period the serum concentration of Cefazolin decreased from about 80 to 40.mu.Math.g/ml, and to about 10.mu.Math.g/ml after about 4 hours.

Experimental Results

(20) A prophylactic dose of the antibiotic Cafazolin was delivered to a patient by the above procedure prior to elective abdominoplasty using the Silberg Tissue Preparation Systems TM Model ME 800 (9801427) Mettler Surgical, Anaheim, Calif.). About 250 cc of prewarmed saline containing 1 gm of Cefazolin was injected under a surgical incision line 201 that was about 5 cm long. Small sample of adipose tissue where taken during the surgical procedure to determine if the Cefazolin would remain above desired concentration reported by Ohge et al., and thus remain sufficiently high through the procedure. Further, blood serum samples were taken during the procedure to determine the potential for a longer term systemic delivery.

(21) As will now be illustrated in FIG. 6, which plots the concentration of Cefazolin over time, it has been discovered that this inventive procedure resulted in much higher adipose tissue concentration of Cefazolin at the start of surgery, for the same total dose of 1 gram as used by Ohge. The Cefazolin concentration in the adipose tissue was about 800.mu.Math.g/ml at the beginning of surgery but dropped about 200.mu.Math.g/ml about 50 minutes later, achieving about a 50 times greater concentration than was achieved by intravenous administration of Ohge et al.

(22) Further, FIG. 6 also indicates that the blood serum concentrations of Cefazolin increased to about 10.mu.Math.g/ml when surgery was completed about an hour later.

(23) Notably, the above method yields antibiotic concentrations in tissue that are far beyond what could be achieved by IV delivery. It should be appreciated that the ability to achieve high tissue concentrations, such as 800.mu.Math.g/ml, while likely limiting the serum concentration to less than 10.mu.Math.g/ml, which less than 80.times. the initial tissue saturation and less than about 10.times. the contemporaneous tissue concentration, is a significant advantage for antibiotic agents that could be toxic at high systemic concentrations. The test data clearly demonstrates that therapeutic levels can be achieved in the target tissues with total doses that are far below the usual systemic dose levels. Even antibiotic such as Vancomycin that is relatively toxic must be brought to sufficient tissue levels to be therapeutic where it is needed. A small fraction of the usual intravenous dose could be given using this method, thus avoiding the toxic effects while treating the patient.

(24) It should be understood that at least one species of antibiotic agents contemplated by the various embodiments of the invention includes antibiotics that are encapsulated in vesicles or are formed as nanoparticles, and more preferably those in which ultrasonic energy enhances the dispensing and delivery of the therapeutically active form of the agent.

(25) It has further been discovered the above method also provide a means to treat patients with MRSA skin infections with antibiotics thought to be ineffective.

(26) MRSA stands for Methicillin-resistant Staphylococcus aureus being a series of strains of this bacterium responsible for difficult-to-treat infections in humans being resistant to a large group of antibiotics called the beta-lactams, which include the penicillins and the cephalosporins. It may also be referred to as multiple-resistant Staphylococcus aureus or oxacillin-resistant Staphylococcus aureus (ORSA). .beta-.-lactam antibiotics are a broad class of antibiotics that include penicillin derivatives, cephalosporins, monobactams, carbapenems, and .beta.-lactamase inhibitors that is, any antibiotic agent that contains a .beta.-lactam nucleus in its molecular structure, and they are generally considered the most widely-used group of antibiotics.

(27) The inventive method was first applied prophylactically to a patent to prevent the spread of an MRSA skin infection in non-elective surgery. Surprisingly, not only was a systemic infection by MRSA prevented, but the MRSA in the surgical field of antibiotic saturated tissue visibly cleared of the infection.

(28) Accordingly, further tests of Cephazolin with a range of different MRSA strains at concentrations well above the dose achievable by IV delivery were made to understand these finding. The Minimum inhibitory concentration (MIC) of Cephazolin with respect to these various strains is reported below in Table 1 in units are in .mu.Math.g/ml of Cefazolin using the broth dilution method. MIC is the lowest concentration of an antimicrobial that will inhibit the visible growth of a microorganism after overnight incubation. STA 29213 is the conventional strain of S. aureus, showing normal sensitivity to Cefazolin with an MIC of 0.5.mu.Math.g/ml.

(29) TABLE-US-00001 TABLE 1 Median Colony Organism MIC/Cefazolin MIC, g/ml Count MRSA 143 64 128 5.73E+05 128 4.18E+05 128 5.94E+05 MRSA 144 128 64 5.12E+05 64 4.43E+05 64 5.15E+05 MRSA 145 128 128 4.87E+05 128 7.50E+05 128 7.54E+05 MRSA 146 64 64 5.79E+05 64 4.62E+05 128 5.68E+05 MRSA 147 64 64 5.22E+05 64 3.71E+05 64 6.83E+05 MRSA 148 256 256 3.45E+05 256 4.30E+05 128 4.37E+05 MRSA 149 128 128 4.93E+05 128 6.97E+05 128 5.28E+05 MRSA 150 512 512 4.67E+05 512 5.08E+05 512 4.92E+05 MRSA 151 128 128 3.66E+05 128 4.91E+05 128 4.54E+05 MRSA 152 4 4 4.03E+05 4 4.44E+05 8 5.55E+05 STA 29213 0.5 3.02E+05 MSSA 1 5.63E+05 MRSA 56 64 128 2.04E+05 (494) 128 5.84E+05 128 6.32E+05 MRSA 116 512 256 7.40E+05 256 6.32E+05 256 5.24E+05 MRSA 142 256 256 4.42E+05 ATCC 33591 256 5.26E+05 MRSA 256 5.18E+05 Mu 3 512 512 3.52E+05 MRSA 512 4.20E+05 hVISA 512 4.42E+05 Mu 50 256 256 5.98E+05 MRSA 256 2.68E+05 VISA 256 2.70E+05 STA 25923 0.5 0.5 5.72E+05 MSSA 0.5 5.76E+05 0.5 5.82E+05 STA 29213 0.5 0.5 4.04E+05 MSSA 0.5 3.94E+05 0.5 5.88E+05

(30) The colony count in the last column is just a quality control measure to insure the correct innooculum.

(31) First, it should be noted that many of these strains, being antibiotic resistant, have an MIC more than 10.times. the 10.mu.Math.g/ml in tissue achieved by Ohge via pre-operative IV administration. However, the most resistant strain, MU 3, has an MIC of about 512.mu.Math.g/ml, about 50.times. the dose required for normal strains. The inventive method of antibiotic administration results in much higher concentrations in tissue of at least the 800.mu.Math.g/ml reported above.

(32) It has now been discovered, inventive method provides a means to achieve the far higher therapeutic levels in the target tissues, with the resulting systemic dose but a small fraction of the amount that is customarily given by other methods, such as Ohge's.

(33) It should also be apparent based on the above teaching that agents to reduce pain, inflammation in joints, and to infiltrate soft tissue tumors, could be administered using this technique and have the same benefit-safety ratio.

(34) It has been discovered that the inventive procedure allows for the application of antibiotics, that would normally not be thought to be therapeutic against certain microbes, at doses at which they are therapeutic. Further, it has been discovered that despite these high local doses that yield therapeutic effects, the systemic concentration is sufficiently low so as to be likely to avoid side effects that might occur in some patients. The systemic amount is a small fraction of the amount that is customarily given by other methods while attaining far higher therapeutic levels in the target tissues.

(35) While the invention has been described with reference to particular embodiments, it will be understood to one skilled in the art that variations and modifications may be made in form and detail without departing from the spirit and scope of the invention. Such modifications may include substituting other elements, components or structures that the invention can be practiced with modification within the scope of the following claims.