GB2340407A - Apparatus for dispensing a metered amount of medication - Google Patents

Abstract

A pocket-sized apparatus for dispensing a metered amount of aerosolised medication comprises a casing (27) defining a cavity, a discharge opening through which the user receives the medication, a valve (59) for the discharge opening which opens under the force provided by inhalation, an air opening (31) through which air enters the cavity and a medication opening. The casing also defines an open pocket for receiving a pressurised canister and there is a passageway to deliver medication from the canister via the medication opening to the cavity. The apparatus also includes means to indicate to the user when to activate the medication at a predetermined inspiratory flow. The apparatus preferably includes an electronic pressure transducer (22) to measure the back pressure of the breath moving through the casing and a cap (58) comprising openings (60) to limit air flow into the casing.

Description

2340407 CASING VM SPIROMETER ?OR METERED DOSE IXHALvR The present

invention gencrally ra.';.ates to a disnenser for aerosolized medication and nore particuiarly to a dispt-n..QQ2r that provides a inetered amount of aerasolized medicaltion and ined6ures the pulmonary function of a SUbjeCt to monitcr this function and to determinQ tho optimum ccnditions for acLzainistering the medicatLon, based or.: 1 routine (date and 'ime) sc.h.eduling of medication, as prescribed by a physician; 2) precise administration of medication based on flowrate, vo1Q.,le, and timing, as outlinad b, the pham--maceutioml manuracturer;. an.d 3) the need to alleviate symptcms, as perce-4ved;by the pattiant.

A metered dope inhalar is a zmall vocket-size'"_' device that generally ccmpris4s two components: (1) a pressurized canister filled with a prcrellant (aerosol) and medicat-icn for opening constricted air-ways in subjects with asthma, chronic bronchitis, omphysema or other such disea ses, and (2) a casing that houses the canister dnd facilitates -ths deliver'y of medicalcion -4ntc a subject-'s lungs. The, subject dispenses the nedication. by inserting a mouthpiece of the casing into his or her mouth and prassing the top of the caalstar while inhaling, Y A subject may use the retered dose inhaler 'separatol or in association wit a "spacer". Spacers are known da-vices th designed -to extend the discharge tube of an inhaler and allow largo d- roplats in the acrosolized medication to settle to their bottoms, Spirometers are devices that measure the breathing volume and the brQathing rate of human subjects. They are the most acou=-ate meens fo-- diagnosing and monitoring pulmonary function. But, they are not pocket-sized dQviczz. in ada,'t4::r, they include a =-.;!t-inlicity of close tolerance components that Tnake tthem susceptible to malfunctions and expensive t.:'- prcduce.

0_her da-7jCe:5 4%-' ',Itt allow subjects to moniltar tfteir pulmonary function include mechAnical poak flow notars. Tntse 4",ow meters, however, a-.s inaccurate. They do not effec-!-ve-,Y detect clinically signif-icant f-unction changes in astl=atics, CnIV:nQ-3LZU=5 nc.

tor ex-ample, 1n addit.Lcn, flOW (PEF) and ret. -,-'--a -,er-ced veium.s r I, Cr.e k:EVI, i.e., the vcll--%i of air ex.;.ialed durl7.

Widely acccmted measure 07, pulmonary -furict-ien) Metered dcsQ -"ha!Ars arg thQ Z....

delive--v 111 those -with. disc-d@rs ald pricr art Includes a wide variety cif suc CZt- dces nct inClude W-fth rea.1-5 According to t'--e present i_rivention an apparatus for d-soensin, a mezered amount of aerosolized meclicaL-'0.'1 for- a h-u-rnan subject, said apparatus a casJnci def-'-n-nc. a - - I- -- -L 1 cavity, a ciisc'narge opening throl-,gn the subject receives tIne medication, a valve -means for the discharge opening, sa4d valve neans opening under force provided by the subject's an air opening through whi-ich air enters Zhe c- - -v, ing, av and a medication oz)en-ing LhroagI ---'-e aerosoli zed medica-l-.on enzers t-n-e CaVitV, 'cass-ze,wa-; means -g- in accordance with one erubcdiment. Of t.n.e present 4nve-nticn, an apparazus fcr dispensinc; a rue-tZlered amount C f ae=solized medicm-Jon and/cr for mcacum-ing pulzzncnar-, func;Om incl-des a cas-4r.g that dEfines an o-pazi cav-zv 0 gh wll-ic'n r u SulD. ect breattes. Tis czsing p--',so defines a d'scha=ce J or exhalec; 94cond, air O-Pen-J-n(r- thzoug'n which t-Jr -1 ar,,J. exiits the ctvity; and a o-nan_fng 4. fluid C 0 =1:-,Ll 4 - t'- - '- - -v; ' -:-weem %the fi--St a-rd seccnd . _cztion w- ca ity he ccenings. 7--Ie cas-jnc; further de---:"-ies an c=e.-. 'pocket for --eceivinc a prGssurizad canistcr Co-.--=-"n-4n= =-edication anct t 0 u r-tt]7., z e d -J c o n c -p a n in c th r c,,! a n Idt. c,c. e c c n t a n, -- s c canister diSC arga 4--Z.0 ure transdi-icer in V_ nzess fluic. cov=unication with the third oloeni-,-ic senses tha pressure Of breath --27-rcuch the ccv-;ty.

The pressure transducer measures tha back prQczurc of he breath which inoves through the cavity betwGan the Lirst and sewond openings. In the embodiment, described above, a differance in tho crocg-zcctional azea betwaen the -,irst and second openings prcduces the back pressure. (The firut opening has a greater cross-sectional area than the second cpeni.-g. ) modification of this embodiment may Include first and second opaningg with th same c--oae-zcct-,onal czea but with screens.

grids, or filter paper ever the second cipening to cri;,atgk tl-,e back pressure. Another modificaticn ray include a fan d-s-csed in the cavity and a phol.-.oca-l1 asserkbly. This mGd-ifica-t--,'cn senses the flow of gaz through llhc ccLvJ-ty.!'at another modification coniprises a valve nember fcr closing the first opening to allow droplets in the nedication to settle;n tne c avity before the sul--jec.1, inhallas the otha--w-s-aarozcl-;zad nadication. This valve me-mber opens under the force of the inhalled breath. of the subject to allow the aerosoiizcl i medication to flow Into the subject.

For 2s more complete understanding of this invantion, one should now refer to the embodiment illustrated in areater detail in the accompanying dra-wings and d-nsc.--ibed below by way of an examtDljp of the Invention. in the arawings:

FIG, 1 Is a perspective vie-w of an -=m-bodi,-nent of the casing and spirometer apparatus of tha present invention; FIG. 2 is a sectional view taken along a langituc-inal axig of the mouthpiece partiun cf the easing; FIG. 3 is a sectional, view taken along line 3-3 in FIG. 2; FIG. 4 is an exmlcded -perspective view of the easing and cLpparat-,a!5f ms, 5 ils a scl-a-ma-t-e. off tl-Q s;ars-4-g, d-4e'oll=Y' and control components of the casing and spirw--eter apparatus; FIG. 6 is the sec-tional view c-' FIG. 2, showing a f ', - - Anod -12 4 cc--' on 0 - the erj:)rd ra:t of 7, GS.!-5; FIG. 7 is the viQ,., cf _P:C. 2, anow_4ng a second modif icattion off --.-,L'zod-7.ent of F:C-5. 1-S; FIG. 8 is the sectional view of FIG, 2, showing a third modifIcation of the emboalment ot FIGS. 1-5; FIG. 9 is a front elevation viQw of the mouthpiece portion' of the casing shcwn in FIG, 8; and FIG.'10 Is a back elevation view o:l the MOU4C-.hp-iece portion o' the casing shown in yiG. 8.

While the following disclosx-aro descr--bez the illverltic,,, in connection with one embodiment and a number cf mcd-1fications of that e one should understand that the irriention is not li-nited to thits embcdi=ent and mod i,'-..ica tic ns, Furthe=,.cre, one should understand that the dra-winga ai:e not to zccle and that graphic synbols, diagrammatic r5UreSentatives, and fragmentary views, in part, -may illustrate the embodinent and mocl-,ficationn. in cc--tain instances, tne d-sclosure may noz include details which are not necozrary for an understanding of the present invention guch as conventional details of fabrication and assembly.

Turning now to the drawings, FIGS. 1 tL-hrough 5 sho.w an embodinent of the casing and spirometer apparattus of the presentinvention at- 20. The apparatus generally includes a pocketsized casing 21 that a user may easily hold in the p^li-a of his or her hand; an electronic pressure transducer 22 (see FIG. 2) which measures the back pressure of the breath noving through the ca:s-il'ig 21; and computer controls 23 (see FIG. 5), including a central processing unit 24, an LCD display 25r anU 5witCheS 25 connected together electrically.

The casing 21 includes a tube segment 27 and a canister:segment 28 fixedly secured (2.a., sonically walded) together to form the cacing. The two =egmei41--z are iraccle cut at and r4gldi--y. plastic or any other material of high st, te, round tube that defines a The tube segment 27 is an elongall eevity or central bore 29, a first opening 30 disposed at one end Of the cavity 29 and a 3econd opening 31 Clapicsed at an opposite end of th.e calilty. The cpening 30 is a j - receives "he ae-oselJzed opening thrcugill which a subjecib - h medication provided tv the e-moara't-.us. The second cnening 317 is an air opening through which a=biont air enters the cavity 29 ihen the subject inhales through the cavity and through 'which air discharcias from tha cavity when the subject exhales into the cavity 29.

The diameter of the bore 29 decreases at a constant rate between the opening 30 and a point 32 (See FIG. 2) to facts. From the point 32 to the minimize air resonance artif =er to facilitate the bore has a constant diam,94" opend.ng 31, t laminar flow. At thQ oponing 31, the tube segment 27 includes a flange portion 33 that reduces --he dianater of the bore to thG diameter of the opening 31. This const-tiction in the flow path of breath moving through the casing 2-, provides the back pressure that the pre-azuro tzancducer 22 sensez.

The tube segment 27 also deffines a bore 34 through which the pressure tCransducer 221 senses the back pressure in the bore 29. TniS bore 34 is part off a third opening 35 that also includes a passageway 36 (Sec F11C. 3) disposed between zha tube segment 27 and the canister segnent 28 and a bore 37 definQd by the caniste-r segment 28. The volune of this opening 35 is sufficiently smal! to rax-4-Iiize tP.e pressure sensitivity off - the ""-ansducer 22.

The canister segnent 28 includes a protuberanc 38 -hat defines a fourth cr med-Lcation op n-.ning 39 for the casing 21. This opening 39 includes a conical cutlet por 1 tion 40 through which aat-oscii=e,-4 inodication sprays out Into the bore or cavity 29 and an enlarged -i--ilet portion 41 that recQivac a nozzle N of a iDressurllzed, canister C. The protuberance 38 extends into the bare 29 ti=oug-li a suitably sized cpQning 42. The distal end cr the protunerance 38 extends lo a point proximate the middle of the bore 29.

The canister searment 23 also defines a pocket'-- 43 that receives the canister C and a pocket 44 that race-,ves the transducar 22, a power 0ource p fur the cc,--,:)uter ccnl,-rols 23 and a res.i..lient 0-rincj 14. 5. (The 0-rin; 45 lj.es around the tore 37 between a wall portion c-, rc=jacen'- the borre 37 and tna transducar 22 tc prevent escape --f the fi-U-Jd t,"1-cwir.g throu h the bore 37 and onto t.'--e transducer 2:_1. The pocket 43 is a round, elongate bore, open at one end f,r rQcQJ-vJing the ca.,i-4zter C.:, lles generally perpendicularly to tha bora 29 in the tube agment 27; bub it may lie at a variety of Other angles to tIe bore 29.

A continuous ridge 46 (See FIG. 3) formed at the bottom of the canister sog.,nent 2a p-roximate the 38 contacts and cooperates witn the tube sag--e4-it 27 to define the passageway 36. (The continuous ridge 46 may be a partion of the tube segment 27 rather than the canister sagment 2S.) Th 15 ridge A6 prevents the air flowing through the oDening 35 from ion 47 disposed escaping from the casing 21. A AIar.94a portaround the Peripherv of the canister sag,,nenl.- 23 at the bottom of the. sagment 1::rcvides a further seal for the gas fLICwing tnrcugh the opening 35- Securing means such as sonic welding or adhesiva secures t_he tube segment 27 and the canister sec=ent 23 aleng the lines oZ contact provided by the ridge 46 and the flange 47.

Alternatively, an annular s:nap fit dooign melded into protuberance 38 releasably secures the tube segment 27 to the canister secj-nant 28. In this alternative, the two segments 27 and 28 are not fixedly secured to ea7h ct-Iher. Thus, a user may 17 after cne or more uses remove and dispoza t.hQ tube úeginant and replace it 'with a,1ew one. Also, a rubber gasket 48 disposed between the tube segment 27 and th.e canister segment 28 provides a further seal around 't-he opening 35. (The gasket 47 includes openinga 49 and So through which, t.,,.t ridge 46 and the tend.) in the construction protuberance 38, respectively, ext wilth tube and canister segments secured together, the pocket between the two segments may or may no', inclUde a gasket 48.

A Polvaater laminate 2azz forn3 a grapilic, overlay with built-in membrane s-witcb.es. (Sae F1G. 4) The graphic everlay provides a clear plastic cover over the Liquid Crystal Display to prctact it, while holding the components in place with adhQc-via. The overiny incy cisa ccnta.'&.zi electrically ccnduez-ive paths fQr -transmitting data externallY and/or suPPIVing Pc.jer from the batter, 1 source p.

As s.ncwn in F12c. 5, the cartrcLs 423 an analog s,gnal from the p=-ezsu--e a= t!i. An a.naicc to d-4gJL,-a-l converter 52 receives Ithe analcg s-;nal and convG.-.,'.s it. ThQ CPU 24 raccivea th.2 OUtpUt Of thR COnVe--ter and inverts it into a series of flow and time points for oach pulmonary test. The NV RAM 24a temporarily Stores the data and establishes an optimum scaling factor to provide the best resolution of thaact date points. It then applies an algorJthm, e.cr., the cubic algorithm of least squares, to the data to determine the instantaneous flow about a pc-4nt in time. TInen, it transmits the data to the spirometer display 25. (The data may aizo b. transferred clectronically to a per so na! computer or raodenthrough physical contact, using a serial in'-Qrtace, or 4-ransferred acoustically to a p.- 1-rans-;uc.-c- lone threugh an audio - using pulse code modulation.) At a prede4e--.--mined -4nsp'--a-"crv flow, the CPW 24 proVides a signal to an transducer 53 which provides an audio signai.. This audlo signal zQ--ves aG an indication, for a subject to ac,:-Jva't-a the medication. Whel the inspiratory flow drops to a predaterminell level, the CPU 224 may provid anothaz oign=l to the audio trar.s,,lucer 53 as an indication for the subject to begin holding his cr her breat.n.

The CPU 24 -may then produce another audio signal after a predstermined tine period to indicate the end of the p2:ccedure.

Z-11G. 6 s.)ic;ws c modirication at the casing and ppirometer of the present invention. in modificat-4on, the bore between the point 32 and the openi ng 31 has the same diameter as thalt. of the opening 311. However, this mcdi.Loicat-;cn Includes a fibrous paper or a retal screen 54 a' %.he opening 31 (o- at any position within the bcre 29) to create the back pressure needed for the pressure transducer 22. it also includes a tube segment 55 that increases the length of the bc--e 34 and moves the Inlet ot cnat i:7ore to the opposite. side of the bare 29.

F1GY. 7 shows a further n.cdifica-tic.n of the casing and sniro.mater amparatus of the present invention. This modificzttiuii aiso inciudes an opening 31- that has the same d-ia=ater as the dianeter of the bore:9 batween the point 32 and 1V the opening 31. This -modification includes a fan 56 ratatab, mounted on a s,'na,,,ot 57 that 1ies fixedly secured tC the -I- -ates, one of 'ts -15. h-v e ry n e- the fa n 5 6:- c - t c-,-ot,ub,era,-ica b-'ades a bcar, of 1-45ht on c pho--ccell, producing a pulso of electricity that a digital ci,-CUit Counts. he faster the air flow, the faster the fan spins and the f_ster the photocell produces of pulses. This modification may alternatively include an additional photocell or a hall effect sensor to datarmine tha direction of the air flow.

FIGS. 8 through 10 show yet another modification of the casing and spiromater apparatus of the present invention. in this modification, the tube segment 27 includes a cap 58 I-or t 6he opening 31 and a flap valve 59 for tte OPQning 30. The cap 58 dafines openings 60 throuqh which inhaled air may anter the bore 29 at a 1.4, mited rate to maximize medication efficacy. The flap valve 59 normally closes the bore or cavity 29 but opens under the forca of a oubject's inhalaticn, Exhalation will nct open the valve in the opposite di-reation.

Acting as a spacer, this modification allows a subject to close tZie discharge opening 30 of the tu-be segment 27 for a short period of ti=a while dischcrging tfte inedication from the canister C allowing t1je large drorlats in thQ aarosolized madicatio-n to settle to the bottom of the cavity 29. In this way, the subject may onlv inhale tthe aercsolized medication and effectivaly deliver the medication Into his or her lungs.

While the above description and the drawings disclose and illustrata one embodiment and a number of modifications of that embodiment, one should understand, of course, that the invantion is not limited to this en.bodiment and modifications. Those skilled in the art to which the invention pertain3 _,zamy make other modifications and other embodiments amployinli the principles of this invention, particularly upon considering the forocloing teachings. Thererore, by the appended claims, the applicants intend to cover any -modi f i cations and other ez. Lbodiments as incorporate those features which constitu-te t.he essential features of this invention.

C-,aims:

1. An apparatus for dispensing a metered amount of aerosolized medication for a human subject, said apparatus comprising: a casing defining a cavity, a discharge openning through which the subject receives the medication., a valve means for the discharge opening, said valve means opening under force provided by the subject's inhaling, an- a-- ocen'L.--, through wn-c:- air enters the cavity, and a opening which 'the aerosolized ned-ication enters the car-'tv, the casing further defining an op-en pocke.: for rece-2v-ng a pressurized ca.n--',s--er and passageway means including the medication opening for allowing mediJca-.-Lo,-Li from the canister to disc'-n.arze directly into the cavity; and means C for indicatina wIner- to activate med-ication at a predetermined Ji-n,-so'Lra--ory flow during an- -risiD-Jrato--v -procedure; said aiDearat,.is be-ing sized _= fit into a palm of a user's hand.

2. The apparatus of c_aim 1, wherein the cas-ng is a J: - generally Ii-shaped r-,,ei--L.,er, the CaV.LV comprises a i'-irsbore that extends from, the first to zhe second opening, and the pocke: Comprises a second bore that extends generally perpendicularly of the first bore.

3. The appara--us of clazin 1, wIherein --n-e casing includes an e"longate tube portion t-n-a-,_ defines -:.'--e e bore and t the discharge or air openings, ---',e discharge open-ing be-ing disposed at one end of the tube and the ai, r opening bei, ng --l-s-cose,-4 at an op-posite end of t_he 5. The apparatus of cIaim 1, wherein the first opening is a greater crosssection than the cross-sectional opening o-- the second opening.

6. The apparatus oiE claim 1, wherein the medication opening includes a passageway that communicates With the pocket. and receives the-'nozzle oil the canister.

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