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Biomedical subjects

F W Merkus

Publications and source records attributed to F W Merkus.

At least 73 records · Page 4Linked to original sources
PubMed1982

The effects of nasal drops and their additives on human nasal mucociliary clearance.

A method for measurement of nasal mucociliary clearance in vivo is described. A drop, containing saccharine sodium and indigo carmine is placed on the edge of the ciliary epithelium in the entrance to the nose. The time between placement and the sensing of the sweet taste as well as the appearance of a blue line in the nasopharyngeal cavity is measured and called the transport time. Two preservatives, two nasal drops and one viscosity-increasing substance have been investigated and the results are compared with their effects on the ciliary beat frequency of chicken embryo tracheas in vitro. The more the transport time is increased by a compound the more the ciliary beat frequency is decreased. Chlorbutol 0.5% increases transport time more and decreases ciliary beat frequency more than benzalkonium chloride 0.006% + EDTA 0.1%. Otrivin 0.1% increases transport time more and decreases ciliary beat frequency more than Rhinoguttae xylometazolini 0.1% (F.N.A.). These results support those obtained with the photo-electric registration device applicated on chicken embryo tracheas and human adenoids as described in earlier publications.

Adult↗
PubMed1982

Intramuscular injection of dapsone in therapy for leprosy: a new approach.

Dapsone is the drug of first choice in the treatment of leprosy. Although the oral route of administration has been mostly used, recent studies of patient compliance revealed that only about 50% of the tables received by the patients are actually taken. It is generally assumed that irregular self-medication favors the development of dapsone resistance. The need for a more reliable route of administration led us to investigate the possibility of an i.m. dapsone depot injection. To achieve effective blood levels for 3-4 weeks, suspensions of large dapsone particles in an aqueous vehicle were made. In a trial with 20 leprosy patients in Nigeria, injection of 900 mg dapsone i.m. as a mixture of particle sizes less than 90 micrometer (20%) and 90-125 micrometer (80%) resulted in a serum level above 0.5 microgram/ml for 18 +/- 5 days with a mean peak concentration of 3.1 +/- 0.9 microgram/ml (n = 10). Injection of 1200 mg of the same particle-size mixture led to peak concentrations of 2.7 +/- 1.0 microgram/ml and maintenance of the level above 0.5 microgram/ml for 25 +/- 3 days (n = 5). After injection of 1200 mg (particle size less than 90 micrometer), serum levels were kept above 0.5 microgram/ml for 21 +/- 5 days with a maximum concentration of 3.9 +/- 1.2 microgram/ml (n = 5). Serum levels were measured using a rapid non-extractive HPLC method. The injections were very well tolerated. Due to these encouraging results, the dosage and formulation will be further optimized.

Adult↗
PubMed1981

The effects of nasal drops on the ciliary beat frequency of chicken embryo tracheas.

The effects of proprietary preparations in the Netherlands and nasal preparations according to the F.N.A. (Formulary of the Netherlands' Pharmacists Association) on the ciliary beat frequency of chicken embryo tracheas have been determined. In general the preservatives, used in the nasal drops, turned out to have a more decisive influence on the ciliary motion than the pharmacologically active constituents. The average time, necessary to decrease the frequency 50% with 1=5 diluted nasal drops (average t 50%(1=5) containing a mercury compound or chlorbutol, is 0.4 h. Quaternary ammonium compounds containing preparations, however, have less influence, average t 50%(1=5) greater than 1.22 h. They are to be used preferably. Nasal drops, used as decongestants, provided that they are preserved with quaternary ammonium compounds, have little influence on the ciliary motion (average t50%(1=5) greater than 1.38 h). Nasal drops containing antihistamines, in contrast, inhibit the ciliary motion largely and almost independently of the preservatives (average t50%(1=5)=0.22 h); the cromoglycate containing preparation, on the contrary, has only little effect in this respect (t50%(1=5) greater than 2 h). Antimicrobial preparations are not preserved and have an intermediate ciliotoxic effect (average t50%(1=5)=0.7 h).

Animals↗
PubMed1981

Pharmacokinetics of etofylline after intravenous and oral administration to humans.

Etofylline is used in many countries as a bronchodilator. In a cross-over study in healthy volunteers serum concentrations and urinary excretion were studied after administration of etofylline (= beta-hydroxyethyltheophylline), intravenously and orally at a dose of 200 mg. Etofylline is a N-7 substituted theophylline derivative which dose not release theophylline in vitro or in vivo. It therefore has its own pharmacokinetic and pharmacodynamic properties. Its plasma decay after intravenous administration shows two-compartment kinetics with a rapid distribution. The alpha-phase lasted on the average 20 min and beta was 0.175 h(-1), corresponding with a beta-phase half-life of 4.1 h. The mean volume of distribution was 0.60 liter/kg, total body clearance 0.106 l.kg(-1).h(-1), and the renal clearance about 0.017 l.kg(-1).h(-1). About 20% of the drug is excreted unchanged in the urine. The curve determined after oral administration can be described by one-compartment kinetics. A comparison of the areas under the curve suggests that the drug was rapidly but incompletely absorbed from the gastrointestinal tract. Its bioavailability was about 80%. Mean peak levels of etofylline were about 3.9 mg/liter after oral administration. The normal dose advocated is 50-100 mg three times a day. With the Wagner-Nelson equation a mean steady state level for this dose can be calculated at about 0.7-1.4 g/ml. Since no information is available on the pharmacodynamic properties, no conclusion can be drawn about the therapeutic effectiveness of the drug.

Administration, Oral↗
PubMed1980

The effects of preservatives on the ciliary beat frequency of chicken embryo tracheas.

The effects of preservatives on the ciliary beat frequency of chicken embryo tracheas are determined, Polar compounds like benzalkonium chloride in commonly used concentrations, decrease the frequency less than 30% after a 20 minutes' exposure. The effect is not reversible after rinsing with Locke-Ringer solution. Lipophilic compounds however, like chlorbutol, cause an arrest of the cilary movement with 10 minutes. The effect, different from the polar compounds, is reversible; but only after a limited exposure-time. Mercuric compounds, like thiomersal, decrease the frequency non-reversibly 30 to 90% after a 20 minutes' exposure. EDTA decreases the frequency 40 to 50%, independent of the exposure-time and in a reversible way. The combination of benzalkonium chloride 0.01% and EDTA 0.05% is recommended to preserve nasal drops.

Animals↗
PubMed1980

The influence of the pH and osmotic pressure upon tracheal ciliary beat frequency as determined with a new photo-electric registration device.

A method for measurement of tracheal ciliary beat frequency in vitro is described. Light transmitted through the cilia is detected by a phototransistor mounted in a microscope, while the frequency is measured instantaneously and the waveform is displayed by an oscilloscope, connected to a transient recorder. Due to the magnification and the method of illumination, the movement of approximately 30 cilia is projected on the phototransistor. In Locke-Ringer solution the waveform shows a very constant amplitude. Interference arises after a noxious influence and is dependent on the frequency of the ciliary movement. The effect of pH and osmotic pressure on chicken embryo and rat tracheal ciliary beat frequency is assessed. The frequency is not influenced between pH = 7 and pH = 10, but higher and lower pH values decrease the frequency. Hypertonic NaCl solutions decrease the frequency of chicken embryo cilia as much as hypotonic NaCl solutions. Rat cilia turned out to be less sensitive for hypotonic NaCl solutions.

Animals↗
PubMed1977

Propranolol serum levels during twenty-four hours.

Propranolol serum levels during a 24-hr period were determined every 2 hr in 9 hospitalized patients with angina pectoris after oral administration of 40 mg of propranolol 3 times a day. After the first, second, and third tablets the mean maximum serum propranolol concentrations averaged 118 +/- 71 ng/ml, 134 +/- 97 ng/ml, and 118 +/- 94 ng/ml and the mean minimum concentrations averaged 21 +/- 18 ng/ml, 45 +/- 25 ng/ml, and 54 +/- 34 ng/ml (+/-SD), respectively. These data show a very wide inter- and intraindividual variation in serum propranolol levels. No relationship was found between serum level and blood pressure or dose (related to body weight).

Adult↗