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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to apparatus for small particle treatment of
the respiratory tract including the lungs.
2. Prior Art
As a result of suggestions made by one of the inventors, in consultations
at Ft. Detrick, Md., scientists at the U.S. Army Medical Research
Institute of Infectious Diseases in 1975 adapted a Collison nebulizer to
deliver a continuous flow of small particle aerosols to mice infected with
influenza virus. This system was described by Young and his associates in
1977 (Young, H. W., Dominik, J. W., Walker, J. S., Larson, E. W.
Continuous aerosol therapy system using a modified Collison nebulizer. J
Clin Microb 1977; 5(2):131-136). Several papers were published
subsequently dealing with the use of this technology to treat influenza
infections in mice with rimantadine (Stephen, E. L., Dominik, J. W., Moe,
J. B., Spertzel, R. O., Walker, J. S. Treatment of influenza infection of
mice by using rimantadine hydrochloride by the aerosol and intraperitoneal
routes. Antimicrob Ag Chemother 1975; 8(2):154-158, amantadine and
ribavirin Walker, J. S., Stephen, E. L., Spertzel, R. O. Small particle
aerosols of antiviral compounds in treatment of type A influenza pneumonia
in mice. J Infect Dis 1976; 133:A140-A144). Another study compared the
effect of ribavirin given by the intraperitoneal and aerosol routes in
influenza infections in mice (Stephen, E. L., Dominik, J. W., Moe, J. B.,
Walker, J. S. Therapeutic effects of ribavirin given by the
intraperitoneal or aerosol route against influenza virus infections in
mice. Antimicrob Ag Chemother 1976; 10(3):549-554) and on the
physiological alterations in mice with influenza, untreated and treated
with ribavirin aerosol (Arensman, J. B., Dominik, J. W., Hilmas, D. E.
Effects of small particle aerosols of rimantadine and ribavirin on
arterial blood pH and gas tensions and lung water content of A2
influenza-infected mice. Antimicrob Ag Chemother 1977; 12(1):40-46).
Berendt and associates made further studies of treatment of influenza in
mice with ribavirin aerosol (Berendt, R. F., Walker, J. S., Dominik, J.
W., Stephen, E. L. Response of influenza virus-infected mice to selected
doses of ribavirin administered intraperitoneally or by aerosol.
Antimicrob Ag Chemother 1977; 11(6):1069-1070).
Based on the foregoing work, technology was adapted for human use by the
inventor in his laboratory (Wilson, S. Z., Knight, V., Moore, R., and
Larson, E. W. Amantadine small particle aerosol: generation and delivery
to man. Proc Sol Exper Biol Med 1979; 161:350-354). Studies in mice in the
inventor's laboratory confirmed the earlier results and, in addition,
showed that a substantial therapeutic effect was demonstrable when
treatment was delayed for as long as five days after inoculation (Knight,
V., Wilson, S. Z., Wyde, P. R., Drake, S., Couch, R. B., Galegov, G. A.,
Novokhatsky, A. S. Small particle aerosols of amantadine and ribavirin in
the treatment of influenza. In Ribavirin: A Broad Spectrum Antiviral
Agent. Smith, R. A. and Kirkpatrick, W. (ed), Academic Press, Inc., New
York 1980; pp. 129-145; Wilson, S. Z., Knight, V., Wyde, P. R., Drake, S.,
Couch, R. B. Amantadine and ribavirin aerosol treatment of influenza A and
B infection in mice. Antimicrob Ag Chemother 1980; 17(4):642-648; Knight,
V., Bloom, K., Wilson, S. Z., Wilson, R. K. Amantadine aerosol in humans.
Antimicrob Ag Chemother 1979; 16(4):572-578). These studies additionally
show that a combination of ribavirin and amantadine increase the
effectiveness of therapy.
While the animal studies, in this case mice, demonstrated the efficacy of
aerosol treatment, and encouraged human trial, the human trials were done
with the realization that therapeutic effect, tolerance and toxicity may
be quite different in man and animals. For example, in Wilson, et al,
1979, Amantadine Small Particle Aerosol: Generation and Delivery to Man,
supra, in using the arbitrary criteria for retention of aerosol in mice
and man, the estimated dosages in mice were approximate four-fold those in
man when similar exposure periods were employed. Up until the present
development, there was no determination made of the aerosol concentration
of the drug which provided an effective, tolerant and nontoxic
concentration for man. In addition, most available nebulizers provide
coarse particles, that is particles having a mean diameter of 10 microns
and over which are too coarse to penetrate effectively into the lungs.
While the small particle or nebulizer apparatus described and used in
Wilson, et al, 1979, generated small particles and produced the results
there set forth, it had the following disadvantages, (1) the valve from
the bag to the mask would clog with precipitated drugs from the aerosol
and the mere insertion of mechanical valves, however efficient, inevitably
creates some obstruction that in some degree obstructs the flow of aerosol
to the patient; (2) the air exhaled by the patient is forced into the
aerosol stream flowing to the patient and the patient then inhales his own
exhaled air from which the drug had been removed; and (3) the efficiency
of the apparatus needed to be improved to provide a higher concentration
of drug per liter of aerosol.
U.S. Pat. No. 4,211,711 is directed to ribavirin, and the small particle
aerosol or nebulizer apparatus of this invention is particularly well
suited to deliver small particle ribavirin for treatment of the
respiratory tract including the lungs.
The most pertinent prior art relating to the present invention known to the
applicant is the prior art set forth above in this section of the
Background of the Invention.
SUMMARY OF THE INVENTION
The present invention is directed to improved apparatus which overcomes the
above disadvantages and which provides continuous flow of small particle
aerosol for treatment of diseases of the respiratory tract and the lung of
man in which the drug is in concentrations which are effective and at the
same time which man can tolerate, which are nontoxic for man and in which
the drug is effectively deposited in the lungs. The aerosol or nebulizer
apparatus of the present invention provides small particle aerosol to the
patient with a maximum diameter of 10 microns with predominately particles
having a mean diameter in the range of 1 to 2 microns. Advantageously,
aerosol or nebulizer apparatus of the present invention has no valves or
other obstructions to the free flow of aerosol to the patient, has an
exhaust and reservoir tube which permits even flow of aerosol to the
patient while inhaling and exhaling, has a dryer which dries the aerosol
thereby reducing its particle size thus permitting the aerosol to readily
penetrate into the lungs, the aerosol being hydrated by moisture in the
respiratory tract and the lungs, and which provides substantially improved
concentrations of drug per liter of aerosol. Advantageously, this improved
aerosol or nebulizer apparatus provides aerosol concentrations of drugs,
such as ribavirin with a respiratory retention of about 50 mg. per hour in
the adult and similar retention efficiency corrected for weight in infants
and children, but which can be increased to a maximum of about 100 mg. per
hour resulting in particularly good results in the treatment of influenza.
Amounts below such minimum respiratory retention can be used for potent
drugs effective in low doses. Higher concentrations risk pulmonary
reactions. The provision of aerosol concentrations of the drug sufficient
for respiratory retention of 50 mg. per hour to about 100 mg. per hour
provides a therapeutic effect and safety in man; although lower doses of
powerful drugs, such as chemotherapy and antiallergic drugs could be used.
The small particle aerosol or nebulizer apparatus is particularly effective
in providing doses of drug lower than usually required by oral or
parenteral administration, thus reducing the risk of toxicity of larger
doses but with the advantage of immediate deposition on the infected
pulmonary surface. Particularly good results have been obtained in the
treatment of influenza.
Accordingly, it is an object of the present invention to provide an
improved small particle aerosol generator or nebulizer effective for
treatment of respiratory diseases with small particle aerosol
concentrations of drugs which are therapeutically effective and safe in
man.
It is a further object of the present invention to provide such an improved
small particle aerosol generator or nebulizer by which diseases of the
lung and respiratory tract in humans are treated by a continuous flows of
small particle aerosol concentration of drugs sufficient for respiratory
retention in man of from about 50 mg. per hour to about 100 mg. per hour.
It is a further object of the present invention to provide an improved
aerosol generator or nebulizer which produces a steady stream of small
particles, that is, particles having a maximum diameter of 10 microns and
predominately in the range of 1 to 2 microns by which drug aerosol
concentrations for the treatment of diseases of the respiratory tract and
lungs can be given safely and effectively.
A further object of the present invention is the provision of a small
particle aerosol generator or nebulizer useful in the treatment of
influenza virus infection in humans by inhalation of ribavirin,
amantadine, or rimantadine, or mixtures thereof in small particle aerosol
form in amounts or concentrations to be effective for treating influenza
which the human can tolerate and which are safe to humans. By such
improved small particle aerosol generator or nebulizer, ribavirin may also
be provided to the patient in treatment of respiratory syncytial virus
infections, parainfluenza virus infections, and other respiratory virus
infections that are sensitive to the drug in vitro.
A further object of this invention is the provision of such a small
particle aerosol generator or nebulizer which has no obstructions, such as
valves, to a free flow of aerosol to the patient thereby avoiding clogging
of the generator or nebulizer with precipitated aerosol.
A further object of the present invention is the provision of a small
particle generator or nebulizer which provides an even flow of aerosol to
the patient while the patient is inhaling and exhaling.
A further object of the present invention is the provision of a small
particle generator or nebulizer in which the aerosol contains high
concontrations of drugs.
Other and further objects, features and advantages appear throughout this
specification and claims.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a flow diagram illustrating a small particle aerosol generator or
nebulizer of the invention, and
FIG. 2 is an enlarged elevational view of the nebulizer head of FIG. 1.
FIG. 3 illustrates a more efficient arrangement of the flow of drug
containing liquid between the reservoir and the reflux vessel which
provides optimum results with less potential for malfunction.
FIG. 4 is a graph in which concentration of ribavirin in aerosol is plotted
against time.
FIG. 5 is a graph in which volume of drug in the spray fluid from the
reservoir and reflux vessel are plotted against time.
FIG. 6 is a graph of the spray factor (calculated).
FIG. 7 is a partial view illustrating a simplified small particle aerosol
generator or nebulizer apparatus in which the reservoir is in the
nebulizer flask.
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings and particularly to FIG. 1, a small particle
aerosol or aerosol nebulizer apparatus of the present invention is
illustrated and designated by the referenced numeral 10, which includes an
inlet tube 12 having the pressure regulator 14 and pressure gauge 16
connected to a portable air compressor, a wall air outlet from a central
service compressor, or to air from a compressed air cylinder, not shown.
Dried air enters the inlet tube 12 after being regulated by the pressure
regulator 14 to a desired pressure of 26 psi. The inlet tube 12 is
connected to the tubes 18 and 20, which each contains a flow meter 22 and
24, respectively, which regulates the flow of air in the lines 18 and 20,
here shown as 2-3 liters per minute in the line 18 and 9-10 liters per
minute in the line 20. The line 18 contains preferably dry dilution air
which passes into the drying chamber 26 and the line 20 is connected to
the nebulizer chamber 28 having the nebulizer head 30 in it. The humidity
of the aerosol particles is reduced in the drying chamber 26 preferably by
mixing with dry dilution air; although, any form of dryer can be used to
reduce the humidity of the aerosol particles and hence their size.
The nebulizer head 30 has the feed lines 32, 34 and 36 extending into the
drug reservoir 38, here shown as containing 400 cc. of the drug in desired
concentrations for treatment of the patient. A return line 40 is provided
from the nebulizer chamber 28 to the drug reservoir 38. The nebulizer head
30 (FIG. 2) is provided with the atomizer ports 42, a port not visible and
44 which are in fluid communication with the feed lines 32, 34 and 36. The
flow of air into the nebulizer head 30 in line 20 aspirates or sucks the
drug solution from the reservoir in the lines 32, 34 and 36, the atomizer
port in communication with line 34 not being shown in this view.
Referring now to FIG. 1 the atomized drug derived from the solution then
flows through the passage 46 into the drying chamber 26; effluent drug
liquid is recirculated to the fluid reservoir 38 in the return line of 40.
The dry dilution air reduces the humidity of the aerosol particles in the
drying chamber 26; the dried and shrunken particles then pass through the
flexible tubing 48 to the face mask 50 for the patient, not shown. The
dried and shrunken particles are small enough to pass through the
respiratory tract into the lungs, the moisture in the respiratory tract
and lungs rehydrating the dried aerosol drug particles for effective
treatment. In addition no valve or other obstruction is provided in the
aerosol flow tubing 48 to the face mask which cause precipitation of drug
from the aerosol causing clogging, decreased aerosol flow and the like.
A flexible line 52 is provided in the connection 54 to the mask 50 which
provides for even flow of drug-containing aerosol to the patient. The
flexible line or tube 52 functions to receive and contain air exhaled by
the patient which would otherwise be forced into the aerosol inflow tube
48 retarding the inflow of drug-containing aerosol to the patient. When
that occurs, such as when the line or tube 52 is omitted, the patient
inhales the air just exhaled from which the drug had been removed. The
continuous flow of fresh aerosol flushes the line or tube 52 of exhaled
air and the tube acts as a reservoir to supply aerosol to the patient
during peak inspiration.
Satisfactory results have been obtained by regulating the air pressure to
26 psi, and having a flow rate of dilution air of 2-3 liters per minute
with air passing into the nebulizing chamber 28 of about 9-10 liters per
minute which results in a flow of about 11-13 liters per minute to the
face mask 50. Other pressures and flow rates can be utilized; however,
highly satisfactory results have been obtained at this pressure and these
flow rates using this particular nebulizer.
It should be noted that most available nebulizers deliver only a coarse
mist, 10 microns diameter and over, which deposit drugs in the nose and
throat areas and not in the lungs. The particle size in a coarse mist and
a small particle aerosol is quite different. The particle size in a coarse
mist is usually greater than 20 microns in diameter, whereas the
aerodynamic mass median diameter (A.M.M.D.) of the small particles in the
present invention is about 1.3 microns with 95% less than 5 microns,
although the diameter of the particles can be as high as 10 microns
provided they are predominately up to 2 microns in diameter.
An alternative arrangement to supply drug solution to the aerosol
nebulizers and to return unaerosolized solution to the reservoir is show
in FIG. 3, in which the letter "a" is added to numerals corresponding to
the nebulizer shown in FIG. 1 for convenience of reference. Liquid is
drawn from the reservoir 38a through silicone tubing (Masterflex, 0.063
inches, internal diameter) through steel tubing in the cap of the
reservoir, thence through silicone tubing 32a to a stopper in an opening
leading to the reflux vessel 28a. From the stopper the fluid flows through
the continuation of silicone tube 32a to one of the three nebulizer ports
52 where it provides drug solution to be aerosolized. The remaining two
nebulizer ports 54 and 56 are supplied from silicone tubing (Masterflex,
0.031 inches, internal diameter) whose tips are submerged in the fluid in
the reflux vessel. Fluid that is not aerosolized is collected in the
bottom of the reflux vessel and returned to the reservoir via the
stainless steel pickup tube 40a with a vertical bevel 58 and silicone
tubing. The vertical bevel allows air to return with liquid to the
reservoir in small bubbles. Large bubbles enter the system when the tip is
not so bevelled and may lead to obstruction in the silicone tubing. The
aerosol generator operates otherwise as described in connection with FIGS.
1 and 2.
Characteristics of ribavirin aerosol produced by the arrangement in FIG. 3
are shown in FIGS. 4, 5 and 6. With 20 mg. per ml. of ribavirin in the
aerosol reservoir 38a the concentration of ribavirin in the aerosol was
160 micrograms per liter at initiation of generation, as shown in FIG. 4.
After 6 hours operation the concentration of ribavirin in the aerosol was
200 mg/l, indicative of the expected excess of evaporation of water during
operation of the generator. The concentration of ribavirin in the spray
fluid, FIG. 5 and in the aerosol, FIG. 4 increased proportionately to
maintain a uniform spray factor (concentration in aerosol in micrograms
per liter divided by concentration in spray fluid in micrograms per liter)
of about 8.times.10.sup.-6, as calculated and shown in FIG. 6. Further
measurements were made after overnight delays between 6 and 7 hours and 11
and 12 hours. Differences in concentration at these times were due to
intentional dilution of reservoir solution with distilled water. The data
indicate highly efficient aerosol generation. The particle size,
aerodynamic mass median diameter, at the fourth hour of aerosol generation
was 1.35 microns, representative of values obtained in measurements at
different times with various methods of operation.
Referring now to FIG. 7, where the reference letter "b" has been added to
numerals corresponding to numerals of FIGS. 1 and 2 and FIG. 3, the
aerosol or nebulizer apparatus has been simplified by removal of the
reservoir 38 (FIG. 1), and 38a (FIG. 3) and by making the nebulizer
chamber 28b large enough to contain the drug solution for continuous
aerosol use, the chamber 28b serving as a common reflux and reservoir
chamber. The nebulizer chamber 28b is designed to hold 300 ml of solution
which is sufficient for 12 or more hours of operation. Fluid is drawn to
the three nebulizer ports through silicone masterflex tubing, 0.031 inches
inside diameter. The ends of the tubes 32b, 34b and 36b project nearly to
the bottom of the chamber 28b. In other respects this embodiment is
identical to the aerosol or nebulizer apparatus of FIGS. 1 and 2 and FIG.
3.
During a period of 5 hours of operation of the aerosol apparatus or
nebulizer of FIG. 7, the initial concentration of ribavirin in the
nebulizer flask (300 ml volume) increased from 31 mg per ml to 35.4 mg per
ml (about 15 percent) a degree of concentration similar to that observed
with the apparatus described in FIG. 3. The output of drug in small
particle aerosol increased from 325 micrograms per liter initially to 343
micrograms per liter at 5 hours, an increase in concentration of 5.5
percent, a value similar to results with the apparatus described in FIG.
6. The dosage used in this study was about 50 percent larger than used in
previous clinical studies.
Unexpectedly, the efficiency of the operation of the modified aerosol or
nebulizer apparatus of FIG. 7 is greater than that obtained with the
apparatus described in FIG. 3. This is measured by the spray factor, an
index of the output which is the concentration of drug in the aerosol in
micrograms per liter divided by the concentration of the drug in the
liquid solution in micrograms per liter. The spray factor for the
apparatus in FIG. 3 was 8.times.10.sup.-6 while it was 1.1.times.10.sup.-5
for the apparatus in FIG. 7 (37.5 percent higher aerosol output from
apparatus in FIG. 7 as compared to that in FIG. 3).
The following Table 1 illustrates the improvement in efficiency of the
nebulizers of FIGS. 1 (and 2), 3 and 7.
TABLE 1
______________________________________
Reservoir Drug
Aerosol
FIG. Concentration
Concentration
______________________________________
1 & 2 15 mg/ml 64 .mu.g/liter
3 15 mg/ml 120 .mu.g/liter
7 15 mg/ml 165 .mu.g/liter
______________________________________
The nebulizer of FIG. 7 is presently preferred due to its unexpected high
efficiency. The nebulizer of FIG. 3 provides substantially improved
results over that of FIGS. 1 and 2, which while not nearly as efficient as
those of FIG. 7 provides satisfactory results.
The following examples are illustrative of the effectiveness of the
treatment of lung disease with small particle drug aerosols having a
respiratory retention of from about 50 mg. per hour to about 100 mg. per
hour.
EXAMPLE 1
College students with illness suggestive of influenza of less than 24 hours
duration were invited to participate in the study and were admitted to the
Student Health Center. They were randomly divided into treatment or
control groups. Sixteen of 22 patients assigned to the treatment group had
strains of influenza A/England/333/80 (H1N1) isolated. Two left the study
for reasons unrelated to the treatment. Seventeen of 21 patients admitted
as controls had the same virus isolated and constituted the control group.
Fifteen of seventeen control patients received saline inhalations
corresponding to period of ribavirin aerosol treatment. The patients' mean
age was 21 years; 5 of 14 treated were males and 7 of 17 controls were
females. One patient had received influenza vaccine more than 24 months
before admission; none of the others recalled receiving vaccine. Seven of
14 treated and 5 of 17 controls thought they had influenza within the past
two years.
Evaluation of Illness and Fever
The degree of illness was assessed at admission and each morning thereafter
until recovery. The physician completed a questionnaire at each
examination that focused primarily on the severity of respiratory and
systemic illness. The questions specifically covered abnormalities of
eyes, ears, throat, chest and lungs, systemic illness as measured by the
degree of malaise or prostration, feverishness or chilliness, headache,
muscle or joint aches, anorexia or nausea, as well as other findings.
After these were recorded in the chart, the physician recorded his
opinion, 0 to 3+, of the degree of rhinitis, pharyngitis,
tracheobronchitis, systemic illness or other kinds of involvement.
Pneumonia was not seen. The major abnormalities at time of admission were
pronounced prostration, headache, eye aches and photophobia, lumber muscle
and joint aching--findings used to measure systemic illness. Temperatures
were recorded every four hours.
Clinical Laboratory Studies
The following hematologic studies were performed at admission and at
discharge from the hospital: hematocrit, red cell count, white cell count,
differential white cell count, hemoglobin concentration and reticulocyte
count. Biochemical tests as follows were performed on admission, at
discharge, and one month later: indirect bilirubin, direct bilirubin,
total bilirubin, blood urea nitrogen, creatinine, glucose, calcium,
phosphorus, albumin, total protein, alkaline phcsphatase, serum aspartate
transminase (ASP), and serum alanine transaminase (ALT), lactic
dehydrogenase (LDH), creatine phosphokinase (CPK), uric acid, and
aldolase. Throat swabs for bacterial culture were obtained on admission;
no bacterial species deemed to be the cause of illness were isolated.
Electrocardiograms and chest roentgenograms were made on admission; none
were abnormal.
Virus Isolation and Quantitation
On admission a throat swab was collected in veal infusion broth containing
100 .mu.g/ml penicillin and 100 .mu.g/ml of streptomycin from every
patient who entered the study. It was refrigerated until inoculated into
Madin-Darby canine kidney, rhesus monkey (LLC), human epithelial carcinoma
(Hep-2), and human embryo fibroblast (WI-38) cell cultures. Standard
diagnostic procedures including immunofluorescence were employed. Baxter,
et al. Maintenance of viability and comparison of identification methods
for influenza and other respiratory viruses of humans; J. Clin. Microb.
1977; 6(2):19-22. Dowdle, W. A., et al. Influenza viruses. In Lennette, E.
H., Schmidt, N.J., eds. Diagnostic Procedures for Viral Rickettsial and
Chlamydial Infections, Washington, D.C.: Amer. Public Health Assoc. Inc.
1979:585. Frank, A. L., et al. Comparison of different tissue cultures for
isolation and quantitation of influenza and parainfluenza viruses 1979; J.
Clin. Microbiol. 10:32-36. The strains from patients in the study were
related to influenza A/Brazil/11/78(H1N1). Several of the isolates were
further characterized in ferret antisera and in monoclonal antibody tests.
All were found to resemble A/England/333/80 (H1N1) (personal
communication, H. R. Six).
The titer of influenza virus was determined on nasal wash specimens taken
at admission and twice daily thereafter for about three days. With the
head tilted back and the breath held, a few mls. of sterile lactated
Ringer's solution was instilled into each nostril. The head was then bent
forward and the liquid blown into a paper cup. This was repeated until
about 8 ml. of fluid was collected. The sample was then frozen at
70.degree. C. until titration was carried out.
Virus titration was performed in 6.times.4 (1.5 cm. dia.) multiwell plastic
dishes (Falcon Plastics No. 3008, Oxnard, Calif.) with MDCK cells.
One-tenth ml. of undiluted and serial 10-fold dilutions of nasal wash
fluid were inoculated onto the surface of each of four wells of freshly
washed tissue culture. After one hour the inoculum was removed by
aspiration and one ml. of Eagle's minimum essential medium containing 2
.mu.g/ml of trypsin (Worthington) and antibiotics were added. End points
were determined after 48 hours' incubation by hemadsorption with 0.075
percent guinea pig red cells.
Tests of Nasal Wash Specimens for Ribavirin
Pre-and post-treatment nasal wash specimens (lactated Ringer's solution)
were heated to 65.degree. C. for one-half hour to destroy virus. Then, to
a measured volume of each specimen 0.1 ml. of one 1:1000 dilution of an
egg pool of influenza A/England/333/80 (H1N1) virus from a patient was
added. The titer of virus was determined in one pre-treatment and four
post-treatment specimens from each of six patients as described above.
As a drug control, ribavirin (50 .mu.g/ml, 100 .mu.g/ml, and 500 .mu.g/ml)
was added to a nasal wash specimen from a volunteer. One specimen of each
ribavirin concentration was heated at 65.degree. C. for one-half hour to
measure the effect of heat on ribavirin; another was kept at room
temperature. Virus was added and titration carred out as above. Heated and
unheated material gave nearly identical results. Results of 50 .mu.g/ml
tests were nearly identical with pre-treatment control specimens.
Hemagglutination-inhibition-antibody Titration
Acute and convalescent speciments were titrated in plastic dishes,
8.times.12, 0.25 ml. conical wells (Linbro-Titerek, Hamden, cn 06517), by
a standard method. Dowdle, W. A., et al. Influenza viruses. In Lennette,
E. H., Schmidt, N. J., eds. Diagnostic Procedures for Viral Rickettsial
and Chlamydial Infections, Washington, D.C.: Amer. Public Health Assoc.,
Inc. 1979:585. Two antigens, influenza A/Brazil/11/78 (H1N1) and influenza
A/Bangkok/1/79 (H3N2), were used in the tests.
Ribavirin Small-particle Aerosol Treatment
Treatment was begun within one hour of admission to the hospital. Ribavirin
dissolved in sterile distilled water in amounts necessary to provide the
specified aerosol concentration was added to the reservoir 38 of the
aerosol generator.
Table 2 shows the hours of treatment and estimated retained dose of
ribavirin. Ribavirin dosage was calculated from one minute expiratory
volumes determined daily using the Bourn ventilation monitor LS75 (Bourn
Company, Riverside, Calif. 92503) with nose clips. Concentrations of
ribavirin in aerosol were determined spectrophotometrically at 207 nm wave
lengths from samples obtained in all glass impingers. Knight, V., et al.
Lack of interference of guanosine with ribavirin aerosol treatment of
influenza A infection in mice. Vol. 20 (No. 4), pp. (not available)
Antimicrob. Ag. Chemother. 1981.
TABLE 2
__________________________________________________________________________
Estimated Retention of Ribavirin Aerosol
by 14 Patients According to Calender Day
DAY 0 DAY 1 DAY 2
Estimated Estimated Estimated
Hours of Retained
Hours of
Retained
Hours of
Retained
Treatment Dose, Mg
Treatment
Dose, Mg
Treatment
Dose, Mg
Hours
Dose
__________________________________________________________________________
Range
5.5-10
270-602
6-12.5
262-867
1-13.5
52-728
15-35.5
664-1962
Mean 7.7 399 11.6 578 4.4 217 22.7
1147
Mean 52 50 49.3 51
retention
mg/hr
__________________________________________________________________________
Dose determination: concentration ribavirin in aerosol (ug/l) .times.
minute volume (liters) .times. 0.7 (retained fraction, based on tests
performed in this laboratory) .times. number of minutes treated divided b
1000 = retained dose on mg.
RESULTS
Febrile Response in Treated and Control Patients
The mean maximum temperatures in treated and control patients by calendar
days are shown in Table 3. Day 0 was the period from admission about
midday to midnight, essentially pretreatment temperatures. These were
nearly equal in treated and control groups. The following day (day 1)
temperatures in both groups had declined but again were nearly equal. By
day 2, however, treated patients had a mean elevation of 36.9.degree. C.
compared to 37.4.degree. C. for controls, a difference that was highly
significant. The trend continued although almost all of the treated
patients had recovered and had been discharged by day 3.
TABLE 3
______________________________________
Mean Maximum Daily Temperatures
in Treated and Control Patients
Calendar Day
0 1 2
______________________________________
TREATED
Temperature 39.4.degree. C.
38.6.degree. C.
36.9.degree. C.
N 14 14 13
CONTROL
Temperature 39.2.degree. C.
38.6.degree. C.
37.4.degree. C.
N 17 17 16
One-tailed t-statistic
NS NS .003
______________________________________
The duration of fever was studied by measuring the hours to sustained
reduction of temperatures below 37.4.degree. C. This value was arbitrarily
chosen, but the results were similar if values of 37.2.degree. or
37.8.degree. C. were used as a basis of comparison. In the comparison
(Table 3), treated patients had fever as described above for a mean of
22.8 hours versus 38.1 hours for controls, a highly significant shortening
of the period of fever. The mean period of illness before admission
(treatment was begun within one hour of admission) was almost identical in
the two groups; both were observed after defervescence for mean periods of
about 18 hours.
Systemic Illness in Treated and Control Patients
TABLE 4
______________________________________
Hours from Onset to Admission and Admission
to Sustained Afebrile State
(37.4.degree. C.) in Treated and Control Patients
Onset to
Admission
Admission
to Afebrile
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TREATED (N = 14) 13.7 22.8
Mean hours
CONTROL (N = 17) 13.6 38.1
Mean hours
One-tailed t-statistic
NS .00
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The systemic illness scores in treated and control patients are shown in
Table 5. At admission both groups of patients had nearly equal degrees of
severe systemic illness. However, by the next morning, a period of less
than 24 hours, treated patients had improved greatly (P=0.004). The trend
continued the next day, but control patients had also shown great
improvement by this time as well. Local findings of rhinitis, pharyngitis
and tracheobronchitis were never severe and showed only a trend of less
illness in treated patients on day 2 (less than 48 hours after admission).
Illness Score in Treated and Control Patients
TABLE 5
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Calendar Day
0 1 2
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TREATED
Systemic Illness, mean score
2.64 1.50 1.0
Rhinitis, pharyngitis, tracheo-
1.52 1.31 0.77
bronchitis, mean score
N 14 14 12
CONTROL
Systemic illness, mean score
2.56 2.18 1.38
Rhinitis, pharyngitis, tracheo-
1.49 1.31 1.14
bronchitis, mean score
N 17 17 16
P-values*
Systemic illness NS .004 .07
Rhinitis, pharyngitis, tracoeo-
NS .NS .07
bronchitis
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*Wilcoxon rank sum test, one tailed.
Virus Shedding in Treated and Control Patients
Virus shedding was measured at admission and twice daily thereafter. There
was a rapid reduction in mean virus titer in treated patients that is
highly significant at 18 hours after admission. There was a slight
secondary rise in virus titer in both treated and control groups due to
lack of cultures from some recovered patients.
Failure to Demonstrate Ribavirin in Nasal Wash Specimens
Since ribavirin was administered by inhalation, it was possible that
specimens for virus quantitation obtained after treatment would be
affected by drug contaminating the nasal wash fluid. The results of a
study of this question show almost identical virus growth in pre-treatment
and post-treatment specimens at all dilutions indicating that no
significant amount of ribavirin was present in nasal wash specimens
obtained for virus titration.
In a further study the nasal wash material was obtained from a normal
volunteer and 0.1 ml aliquots containing 50 .mu.g/ml, 100 .mu.g/ml and 500
.mu.g/ml were tested as above. Some inhibition of virus growth was
observed in undiluted specimens containing 100 .mu.g/ml and 500 .mu.g/ml.
At 1:10 dilution only specimens containing 500 .mu.g/ml inhibited virus
growth. At higher dilutions no drug effect was detected. A concentration
of 50 .mu.g/ml showed no inhibitory activity. Thus concentrations of
ribavirin of up to 50 .mu.g/ml would not have been detectable in these
tests.
Serologic Response to Infection
Acute and convalescent hemagglutination inhibition antibody titers were
made. The titers to the H1N1 virus were low in both treated and control
groups at admission. There was a trend of greater serologic response in
treated patients (P=0.084). There was no rise in titers to the H3N2 virus
in convalescence from a 1:14 mean acute titer.
Clinical Chemical Tests in Treated and Control Patients
Clinical chemical tests were performed on 14 treated and 17 control
patients at admission; at discharge there were 13 treated and 15 controls,
and at one month there were 11 and 17 sets of tests performed.
Drug toxicity would be expected to be manifested in specimens taken at
discharge from the hospital shortly after stopping treatment. In the whole
series of tests the only significant difference between means of treated
and control patients at this time was an abnormal elevation of creatine
phosphokinase tests in treated patient | | |
