| 摘要 |
<p>A drug delivery device (10) comprises a housing (11) containing a gas generator (28) controlled by electronic control means (27). The gas generator (28) is operable to generate a gas into a reciprocable chamber (25), whereby reciprocation of the chamber (25) causes a lever (19) to reciprocate a pawl (18), and this action causes a ratchet (17) to drive a piston (16) incrementally and thereby deliver small volumes of drug (13). In preferred embodiments, the pawl (18) has two pawl members (31, 32) which alternately drive the ratchet (17) forward, thereby decreasing the minimum deliverable volume for a given ratchet tooth tolerance. The reciprocating chamber (25) is, of very small relative volume and unlike continually expanding chambers, is independent of temperature and pressure effects in normal use, such that the drug delivery rate achieved is therefore constant. The device (10) may also be provided with manually actuable means for delivering a bolus dose of drug when necessary.</p> |
